camera obscura

5/27/2018 Camera Obscura

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THE WRIGHT CENTERFOR

SCIENCE EDUCATIONInnovative Curriculum Series,Edited by Cathleen Banister-Marx

Tufts University, 4 Colby Street, Medford, MA 02155(617) 627-5394 FAX (617)627-3995 [email protected]

http://www.tufts.edu/as/wright_center

The Camera Obscura & Pinhole PhotographyJim Kosinski

Wright Center for Science Education, Tufts University

Tufts

University

Massachusetts Space

Grant Consortium

Fondation H.

Dudley Wright

Commonwealth

of Massachusetts

Foundation for

the Future


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The Camera Obscur a and Pinhole PhotographyA Hand s-on Process App roach

Jim Kosinski

Wright Center for Innovative Science EducationTufts UniversityMedford, MA

Table of Contents

I n t r o d u c t i o n ......................................................................................1

A Br i e f H is tor y of t he Natur a l Camera....................................2

Const r uc t in g t he Camera Obscur a............................................5

Observi ng t he Basic Image in th e Camera Obscura ............8

Add i t i ona l dev e lopm en t a l Act i v i t i es....................................11

Stu dent Assessment ..................................................................... 17

Meet ing Nat ional Sc ience Educat ion Standards ..............18

The Pin hol e Camera ...................................................................... 19

Const ru ct in g a Fi l m Can Camer a........................................22

The Black & White Dark roo m Process...............................25

Demonst r at ing t he Dark room Process .............................28

Cont act Pr in t i ng .......................................................................34

Disposal o f t he Chemicals ....................................................36

Mater ia ls .......................................................................................... 37

References ....................................................................................... 38


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Introduction

In the teaching of arts and science, the creation of a roomsized giant camera and the use ofpinhole cameras generates a high degree of enthusiasm for learning in students of all ages.

The images formed by the camera obscura are fascinating. No special technology is required

and the entire event can succeed on even the smallest budget. Knowledge and appreciation oflight and image formation are gained directly in a handson, interactive environment. Thisproject will work well in elementary, middle and high schools.

The activities included here are developmental and designed for success. A giant camera canbe demonstrated in one or two class periods using only recycled materials and tape, or theproject can last a week or longer by adding a pinhole camera and darkroom component. Withsmall cameras made from recycled film canisters and pie tins and the use of small sizes ofphotographic materials, the darkroom component is very manageable and can be amazinglylow in cost.

Black and white processing can even take place without a darkroom if you have a fi lmdeveloping tank and a photographers changing bag to load the camera and to transfer the

paper into the tank for developing. Since its completely dark inside the changing bag, you canmanage the whole creative process in any location, either outdoors or in room light.

The term camer a obscur a(Latin) means dark chamber. Centuries ago it was found that asmall aperture would naturally form an image inside a dark space such as a cave, nomadic tentor room. Artists would bring their materials into such a room to draw the surrounding scene ingreat detail and people would entertain themselves by watching the images move in real time(the first movies).

Entert ainment & educat ion in a Victorian camera obscura

http:/ / www.brightbytes.com/cosite/cohome.htm

The camera obscura evolved into a portable tentlike device. This trend continued and camerasbecame smaller and more boxlike. Apertures shrank along with camera size in order tomaintain sharp focus, finally reaching the diameter of a pin. This served as the prototype forthe first cameras that used chemical means of recording images. Lenses were added tobrighten and sharpen the image, but pinhole cameras have always been part of photography.In our time, there is a widespread renewal of interest in photography without lenses.

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A Br ief Histor y of t he Natur al Cam era

The camera obscura is thought to be one of the first three optical devices used by man. Thesecond is the shadow. The third is described with an ancient joke that goes like this: Hey, Iveinvented a device that can see through walls! Really, what do you call it? A window!

It has been known for centuries that in nature a small hole can form an image. This method ofnatural image formation predates the use of lenses. Early recording of the image was done byhand. At first, an artist or astronomer would create a dark room with a small aperture thatwould cause an image to be formed inside the room. The image formed could be quite largeand could easily cover more than one wall. In fact, the image existed throughout the room butwas only visible when light was intercepted by a solid object, such as a wall, paper or canvas.

Translucent materials like onionskin also showed the image quite well.

At first the image baff led the artist-scientist. It was upside down and backwards compared tothe way the eye saw the scene outside. It was then discovered that a straight line could bemade from any point on the image, through the aperture to the corresponding point in thesubject. It held true for every point. These observations consolidated our understanding that

light forms rays that travel in straight lines.

Came r a o b s cu r a sh ow i n g l i g h t r a y s t r a v e l i n g i n st r a i g h t l i n e s,

Reinerus Gemma-Frisius, 1544

http:/ / www.cinemedia.net/SFCV-RMIT-Annex/rnaughton/CAMERA_OBSCURA.html

The artist could intercept the image anywhere inside the room. If it was captured close to theaperture, the image had a wide angle of view. If an image farther back from the aperture waschosen, the angle of view was decreased. From these early exercises the theory of perspectivedrawing was developed and applied.

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An art i st work ing in a portable camera obscura, Athanasius Kircher, 1646


Most early practitioners were concerned with images showing normal perspective, which wasachieved when the screen was placed perpendicular to the axis of the aperture. However,some experimenters placed the recording media at different angles resulting in distortedperspective. Interestingly enough, images that looked distorted from one point of view mightlook quite normal from another. This gave rise to the art of t r omp e l oei l, French for foolingthe eye.

The camera obscura underwent the process of miniaturization. It was built as a portable tentor room, further shrunk to the size of furniture and finally made small enough to be carried byhand and placed on a tripod or solid object. As camera size decreased, it was necessary toreduce the diameter of the aperture in order to maintain sharp images. As apertures becamevery small, it became difficult to see the image. This problem was overcome when the lens,which could focus light using a relatively large aperture and form a brighter image, wasintroduced. The portable camera obscura with a lens is the first prototype of todays viewcameras.

An art i st dr awing on a desk-sized camera obscura in t he 18th centur y.


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The round hole and the lens produce two very different kinds of images. A round hole does notfocus l ight but allows rays of l ight to pass through. The rays are small and once passed theaperture continue to widen inside the dark chamber. Every point in the subject, whether nearor far, is focused exactly the same way by the aperture. Since objects from the camera toinfinity are in sharp focus, the camera obscura and pinhole camera are said to have infinitedepth of field.

The lens, on the other hand, takes a ray of light from a point in the subject and bends it so thatit is completely refocused at a single point behind the lens, producing very sharp details.However, the ability of a lens to accomplish this task does not extend to all objects in front ofthe camera. It can only focus a range in the middle ground of the subject. This sharply focusedrange is called depth o f f ie ld , which shifts as the lens is focused on subjects nearby or faraway. Thus, images formed by lenses have areas of sharpness and areas that are not focusedsharply. The images are also upside down and backwards unless optically corrected by prismdevices.

Finally, with the introduction of chemically based photographic emulsions (c. 1820), it becamepossible to capture a permanent image in a short time and reproduce the image easily. Thematerials were placed in devices with and without lenses in order to make photographs.

Lensless cameras were small with apertures close to the size of a pins diameter and becameknown as pinhole cameras. Apertures of this size have been made by countless amateursusing pins. The pinhole camera became an important tool in education and the arts and alsoevolved as a useful tool in science, astronomy and space exploration. The heritage of thecamera obscura along with pinhole cameras made by amateurs, professionals and cameramanufacturers continues to be rich and active and is undergoing something of a renaissance atthe present time.

Box camera obscura, early 180 0s, protot ype of the vi ew camera st i l l i n use today

http:/ / www.newcastle.edu.au/department/ fad/ fi/ woodrow/anal-2.htm

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Const ructi ng the Camera Obscura (You cando this at home!)

Choose An Approp r i ate Room :

Interesting environments make interesting images. The view outside the camera obscurashould be bright and a room with an outdoor window works best. A higher interest level will be

gained if there are objects moving in the view, such as vehicles, rivers, flags, etc. The outsideshould be accessible so that students can go out and get into the picture themselves. Also, i t isa big advantage if the sun shines on the window.

Here is the scene outside the way a digital camera sees it:

Cover t he Win dows:

The room must be dark inside in order to see the image clearly. If you like, the room-sizedcamera can also be used as a photographic darkroom for further study. Many differentmaterials can be used to cover windows. Small sections can be taped together. Black tape canbe used to cover any small holes where light comes through.

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This bathr oom is good for a camera

obscura because i t has a small win dow

and the wal ls are white.


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Mater ia ls :

Here are a few materials that are inexpensive and easy to find:

Black plasticRecycled cardboardPhoto-backdrop paper

Heavy duty aluminum foil on wide rollsBlack clothWood panels

In some situations you might have to put on two layers to achieve suff icient darkness in theroom. If you want to use the room as a photography darkroom, all sources of white light mustbe eliminated.

Aper tu res :

Different apertures are used to show different properties of image formation. These aperturesneed an opening to be set into. Cut a 2-inch square pilot hole in the window covering, justabout in the middle of the wall. More than one pilot hole can be placed in the window to allow

for more than one group of students to be active or to study the optical effects of more thanone opening.

It is not actually necessary to use a room for this project. A large cardboard box, a handmadecardboard structure, a van or school bus along with many other options are at your creativefingertips. This will integrate the project with design, structure and architecture themes.

Simple materials should be used to make apertures, such as black paper, cardboard, aluminumbaking pans or soda cans. They can be cut with a scissors, X-acto knife or can be drilled,depending on the capabilities of the students and teachers. Metal apertures need to be sandedfor safety to remove any burrs and sharp projections. An assortment of washers can be used tomake small apertures.

Basic apertures are round and the size of the apertures should vary. Common objects can beused for reference. These include a quarter or dime. Washers and other readymade objects willprovide smaller apertures without the need for tools. The shape of the apertures can also vary.

Try squares, rectangles, triangles, slits, stars, ellipses, etc. Apertures with more than oneopening can also be created.

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Even the p i lo t h ole wi l l for m a

simpl e image inside the room .

The picture on the wal l is b lur ry

because the pil ot ho le is large.

The wind ow is covered. A pi lot hol e is

cut out near t he center of the cardboard.


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The apert ur e on the lef t was made by tr acing t he shape of a coin w ith an X-acto k nif e.

The one on the r ight was made with a hole pun ch.

Apertures are placed over the pilot hole in the window. They should be easy to work with andthe pilot hole must be covered so that light only comes in through the aperture itself. To

accomplish this, the apertures can be taped onto a sturdy cardboard mount that is about 4-inchsquare with the center removed to allow l ight to pass through the aperture.

Viewi ng Screen:

Viewing screens can be made from reflective or translucent materials like white paper, tracingpaper or drafting fi lm. A translucent screen is easier to use in demonstrations because theimage can be viewed from both sides. Screen material can be taped onto a frame cut out ofcardboard, foam core or any other rigid material at hand. It can be any size, but a two-footsquare is adequate for most demonstrations.

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Observ ing t he Basic Image in a Camera Obscura

Once you have placed an aperture in the window and can see the image, the fol lowingquestions can be used to help students understand what is physically happening in the camera.Start with an aperture about the size of a dime for rooms about ten feet deep. Larger

apertures can be used for bigger rooms.

Where is t he im age?

Without a screen, the image is located on all the surfaces that the light encounters. A hand-heldviewing screen wil l show that the image can be formed throughout the room.

How is th e image or ient ed?The entire image is upside down and backwards. Light rays from objects in the scene travel instraight lines through the aperture to form the image.

How sharp is t he image?Discuss the relative sharpness of the scene. Sharpness changes with aperture size.

The apertu re used to pr oject the im age on the lef t h as a larger di ameter t han the one used

to cr eate th e image on th e righ t. Image sharp ness increases as apertur e diameter d ecreases.

How br i ght is th e image?

It may take several minutes for your eyes to adjust to the light level in the camera. At first theimage will be hard to see. After the eyes adjust, it will be much easier to see the details.Brightness changes with aperture size.

Is there any mot ion in t he p ic ture?Objects moving outside wil l move in real time inside the giant camera. This happens at thespeed of light! Students enjoy watching each other.

What about co lor s?On a white wall the colors are accurate but they will pick up the tint of other colors on the wallor screen.

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Observ ing t he Basic Image in a Camera Obscura

1. Where is the image?

2. How is the image oriented?

3. How sharp is the image?

4. How bright is the image?

5. Is there any motion in the picture?

6. What about colors?

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Name Class Dat e


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Act iv i t i es for the Camera Obscur a:

When the basic image is realized these follow-up activities can be helpful. They are easilyaccomplished in one class period.

Pass the viewing screen around the room to show that the image forms almost

everywhere. Try to find a place where the image does not form.

Insert apertures of di fferent sizes to show that image sharpness increases with smallerapertures and brightness increases with larger apertures.

Change the distance from the screen to the aperture to show that angle of viewincreases as you approach the aperture. Dif ferent sized apertures will focus an image atdifferent distances. Smaller apertures focus closer to the window.

Send a group of people outside to move around. Continue until everyone has had achance to participate.

Put snow or water on the outside of the window and watch the movement in the camera.

When these slide down the window over the aperture, they wil l be seen as sliding upthe wall on the image, seeming to defy gravity.

Place a simple lens, such as a magnifying glass, over the aperture to see how a lensmakes a sharper and brighter image. Youll have to move the screen back and forth tofind the correct focusing distance from the pinhole. The distance at which far awayobjects are focused by a lens is called the foca l leng t hof the lens.

Encourage students to try a simple experiment of their own choice.

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Addi t ional Development al Act ivit ies

Basic Act iv i t i es:

Make apertures with different shapes. Make apertures with more than one hole. Here

are some ideas:

Place the viewing screen at different angles to the axis of the aperture for specialeffects.

Make a curved or bent viewing screen.

Draw the projected image on a large piece of paper (a good group activity). Take thedrawing outside and compare it to the scene. Objects outside that are close to thewindow will be magnified in the camera.

Invite a photographer into your classroom.

Your own ideas:

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I n te rmed iate Ac t iv i t ies

Explore what kind of images form on the surface of di fferent objects, such as a baseball,ice cream cone, glass of milk or other objects. You can cover the objects with whitepaper to see the image clearly.

Place colored cellophane, gels or f ilters over the aperture to change the color of theimage. Color mixing can be studied. For example, blue + yellow = green.

Draw portraits of people sitting outside the window.

Use a mirror to redirect the image. How does a mirror change the orientation of theimage?

Measure the angle of incidence of the sun (the angle between the ray and the floor).

Take some photographs with a lens camera of the image inside the camera obscura.

Will a tube form an image? Hold a bundle of straws together with a rubber band and

place it over the opening in the window.

Search the web for camera obscura installations.

Take a class trip to an existing camera obscura installation.

Your own ideas:

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This Victorian era camera obscura in New YorksCentral Park was photographed with a stereocamera so it could be seen with a 3D effect.

http://brightbytes.com/cosite/collection.html

Heres a playful one in San Francisco,constructed a century later.http://www.cinemedia.net/SFCV-RMIT-

Annex/rnaughton/CAMERA_OBSCURA.html


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Advanced Ac t iv i t ies

Mark the location of the sun at different times of day. When the marks are connected,you will have a sun track for that day. If this is extended over a period of time, youwill be able to chart the path of the sun over the course of a season or year. This

technique can be used to make a solar clock.

Explore the optical properties of different lenses. Include image formation, focal length,combinations of lenses, etc. Encourage students to try their own ideas.

Design and build a cardboard cameraobscura room that can be carried from place toplace. Cardboard and duct tape are the easiest materials to use.

Design a system for determining the speed of objects outside the camera obscura usingthe image that is projected on the inside. Try cars, bikes, people walking, dogs, cats,ants, etc.

Try this at night if you are in a dark neighborhood. Turn on the lights inside the camera

obscura. Bring the viewing screen outside and hold it near the aperture. What do youthink will happen? This activity turns space into a camera obscura and is a good analogyfor microcosm and macrocosm.

Make a camera obscura at home.

Start a project to design and build a camera obscura in your community.

Start a photography club.

Your own ideas:

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Draw t h i s scenic landscape as i t woul d appear in s ide a camera obscura.

Draw th is cup of cof f ee as i t woul d appear i n a camera obscura.

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Nam e Class Dat e


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Teacher Page:

Draw t h i s scenic landscape as i t woul d appear in s ide a camera obscura.

Draw th is cup of cof f ee as i t woul d appear i n a camera obscura.

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Angle of View

Measure the angle of view at different distances behind the aperture. Start very close to the

window. Graph your results.

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Name Class Dat e

Distance fr om Apertur e

(cent im eters or meters)Angle of View (Degree)


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Apert ur e Diameter

For a series of round apertures of dif ferent sizes, measure the distance from the aperture to

the plane where the sharpest image forms. Graph your results.

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Aperatur e Diameter

(cent imeters or mi l l im eters)Distance to Plane of Sharoest Image(centimeters or milimeters)

Name Class Dat e


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Student Assessment

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Motion is projected in realtime at the speed of light.

You can see things movingin the camera obscura.

Motion

Image colors can bemodified with filters.

The image colors are thesame as the subject if youuse a white surface forviewing.

Colors

The image formed by a lensis restricted to a very smallvolume of the room.

A lens forms a sharper imagethan a simple aperture.

Images Formed by a Lens

Angle of view is a function ofthe distance from theaperture to the image.

An image closer to theaperture has a wider angle ofview.

Angle of View

Perspective can be distortedby changing the angle of theviewing screen or othersurface the images fall on.

The images formed at rightangles to the axis of theaperture have normal, one-point perspective.

Perspective

The distance at which asharp image is formed is afunction of the aperture

diameter.

A smaller hole makes asharper image.

Image Sharpness

Images can be reorientedwith mirrors and prisms.

Images are formed upsidedown and backwardsbecause light rays travel instraight lines.

Image Orientation

The image forms throughoutthe chamber and must

encounter a reflectivesurface to be seen.

A small aperture naturallyforms an image in a camera

obscura.

Image Formation

Concep t Basic Level Beyond t he Basics


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Meeting National Science Education Standards

The combination of a camera obscura and making black and white photographs with pinholecameras is an ideal way to present a project that meets all of the educational standards in amanner that is easy to implement and is designed for success in elementary, middle-school and

high-school programs. Here is a brief l ist of topics for each standard of science content. Topicsare easily integrated. Individual teachers can add to this list according to the uniqueness oftheir educational environment.

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A very interesting time line can be constructed usingthe resources cited

History and Nature of Science

Photography is used to help resolve social issues (seework of Lewis W. Hine, Margaret Bourke-White, FarmSecurities Administration)

Photography as holistic education Self discovery & communication

Personal & Social Perspectives

Creating tools based on natural phenomenon Integrating diverse physical systems Study of high energy particles with pinhole cameras

Science & Technology

Study of the Earths path, sunspots Viewing an eclipse with a camera obscura Use of pinhole cameras on space mission

Earth & Space Science

Image formation by living creatures Pupil dilation related to apertures Chemical recording of images in the brain Medicine, recording growth in the womb (Nilsson)

Life Science

Acids & bases Process control Time, fraction of a second - year Recovery of silver from used fixer

Physical Science

Hands on learning of how things work Opportunity for personal inquiry, what if I.? I can record the world around me

Inquiry

Biology: vision and model of the eye Physics: optics, light, total darkness full spectrum Chemistry: chemical reactions, solutions, silver Extended to other fields (art, history, journalism)

Unifying Concepts


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The Pinho le Camera

A pinhole camera is a logical projection of the camera obscura. Making pinhole cameras fromrecycled materials is a rich tradition in photography and in classrooms around the world.

The pinhole is an important part of the camera because it forms the image. It can be anythingfrom a hole quickly made in a piece of paper with a common pin to one that was calculated bya mathematical formula and tooled with high-tech instruments. The important thing is to makesure it is the best pinhole for your application. The camera body can be made from anything, aslong as its dark inside!

A tiny hole is needed for this type of photography. It does not have to be round to actuallyform an image. Slits, slices and other configurations will form images unique to their shapesand are worth experimenting with. However, the round pinhole is the true workhorse of thisgenre.

There are a range of materials available for making pinholes. The most common are paper andmetal. If paper is used, it should be thin, opaque and sturdy enough to withstand the

penetration of a pin. The most common metals used are brass and aluminum. Thin brass andaluminum stock can be purchased at hobby shops. Aluminum baking pans or soda cans arewidely used (foil is too flimsy). Pinholes have been made with gold, silver or lead worked into athin sheet. Silver can be placed in selenium toner for a few minutes for a protective coating.Both paper and metal pinholes can be darkened with permanent marker to absorb stray light.

It is best to take time in making the pinhole in order to get the best results. It only takes a littleextra time and attention to turn an okay pinhole into a really good one. The hole should be asround as possible and free of debris. A few minutes of care in drilling, sanding and checking thehole will result in many hours, if not years, of enjoyable photography.

The two main variables that affect image formation are the diameter of the pinhole and thefocal length. The focal length is the distance from the pinhole to the paper or fi lm. For sharp

pictures there is a direct relationship between the pinhole diameter and the distance from thepinhole to the emulsion. Shorter distances require smaller diameters in order to maintain sharpdetails.

If the hole gets too small, dif fraction and interference effects wil l cause the image to becomeunsharp. The image will also be out of focus if the aperture is too large. These observationslead us to the idea that there is an optimum pinhole diameter for each camera length when itcomes to image sharpness. If the material is thick, the light acts as if it is passing through acylinder instead of a plane, again forming a more softly focused image. These are not errors,they are attributes. A photographer uses these concepts creatively!

Very Precise Pinholes (opt ional)

There are so many published formulas to calculate the optimum pinhole diameter that it maylead you to believe it does not exist! The reason for so many formulas is that they werederived to fit the specific conditions of light and geometry used in the numerous experimentsof each practitioner. They can help in getting started, and you can try out different sizes to suityour whimsy. The numbers in the formulas are oriented to very specific units, so be careful.Here are a couple of handy ones:

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A = the square root of [55 times F] -or-

A = 7.416 times the square root of F

where A = the aperture diameter in thousandths of an inchand F = the focal length of the camera in inches

(Renner, 1995, p118)

and

D = the square root of [0.00007 times V] -or-

D = 0.0084 times the square root of V

where D = the aperture diameter in inchesand V = the focal length of the camera in inches(Photo Lab Index, 1971, p9-29)

Lets see what happens if we want to design a ten-inch camera using these two formulas (the

square root of 10 = 3.162).

A = 7.416 x 3.162 = 23.5 thousandths = 0.0235 inches

D = 0.0084 x 3.162 = 0.0266 inches

These figures differ by about 11%. In practice, this difference is nothing to worry about whenyou make pinholes with a sewing needle!

Measur ing Pinh ole Di ameters

Close inspection of a needle reveals quite an interesting fact. They are not of uniform diameterfrom tip to eye! The very tip has one angle of taper while the rest of the needle is tapered atanother angle altogether. Where does the diameter listed in the chart apply? Suppose you haveneedles and dont know their size?

A simple technique can be used to measure diameter quite accurately.It was used by Isaac Newton, the father of classical physics, in hisstudies of l ight. Simply l ine up a number of needles unti l they equal ameasuring unit and then divide the total length [span] by the numberof needles. The most accurate arrangement is when every otherneedle faces in the opposi te direction and they are taped together tokeep from moving. With a good ruler, you can easily measure thediameter at any point on the needle using this method.

These needles were placed on a magnet. It took 13 needles toprecisely measure 3/ 10 of an inch on this architects ruler. The needlediameter is 0.3 inch divided by 13 = 0.23 inch. Your precision wil lincrease as more needles are added. You can enlarge thisdemonstration on an overhead projector if you use a transparent rulerand clear tape.

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Creat ing Pinholes

In forming the pinhole a combination of pressure and rotation is used to make the hole. Sinceneedles are very hard to handle it is best to make a simple tool to accomplish the task. Theneedle can be pushed into a pencil eraser or a small piece of wood or it can be placed in anXacto knife holder. Some people just wrap masking tape around the eye end, making it easier

to hold.

The best pinholes are made a little at a time. Start by pushing and turning the needle until itjust pokes through the pinhole plate if using soft materials (or a small dimple is formed on theback side if using hard materials). Alternatively, you can push the needle with one hand whilerotating the metal with the other hand. Use a fine grit sand paper to remove the dimple. Thenplace the needle on the same point and repeat the motion. Sand it down. Keep repeating theprocess until your hole is formed and the needle is far enough through the hole to create thediameter you need.

In practice, especially with younger folks, the needle often pushes through on the first try. Notto worry! It will still form a pleasing image. Another problem shows up when the needle missesthe first hole and makes another one right next to it. This can be seen when you check the

pinhole closely with a magnif ier, reading glasses or loupe. A camera lens, detached from thebody, makes an excellent magnifier when you look through the front. You can put the pinholein an enlarger or a slide projector to check it. An overhead projector works, too. Be extr acarefu l o f sharp edges when you br i ng th at p iece of meta l c lose to you r eye to checki t !

If there is any debris in the hole, it can be removed using the point of the needle and sandpaper. For thicker metals, initial sanding can be done with a medium-fine material (e.g. 240grit) while final sanding should be done with very fine material (400 or 600 grit). For thinnermetals, use very f ine grit only. Sand both sides for smoothness and also to reduce the metalsthickness.

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Const ructi ng a Film Can Camera

Two black plastic film canisters, a pinhole and some black vinyl tape are all you need to makethis whimsical camera. There are some advantages to this camera size. Due to its short focallength the exposures are relatively fast. You can work outdoors with exposures less than five-

seconds i f its a bright day. Film cans are readily available. Photo shops like to give them awayfor recycling. These cameras can be made quickly with no special tools. Students can eachmake more than one camera for f lexibil ity and experimentation.

The film canisters can be cut with scissors. The one onthe left is for the shutter and was cut to make arevolving slit: Remove the bottom completely and thencut a vertical slit about 1/8-inch wide all the way fromthe top to the bottom. Use the second canister to makethe camera body. Punch a small hole (use a one-holepunch) near the center of the canister. This acts as awindow for the pinhole plate. Make sure the cap fitstightly. A pointer of some sort placed on the cap helps to

locate the pinhole when you are ready to take a picture.

Mater ia ls :

Scissors or other cutting device and black vinyl tape Small rectangle of metal (the pinhole plate) cut from a soda can, Aluminum baking pan, etc. (3/4" square) Sand paper (Very fine-240 or 400 grit) Needle (size 9 or 10) inserted into a pencil eraser Mat or thick piece of paper to work on so your table wont get scratched

Procedure:

To drill the hole: rotate and push the needle into the pinhole plate until it goes through themetal. Sand the metal unti l i t is smooth. Open the hole a little at a time, alternating sandingand dri lling. For these small cameras, the needle should penetrate just a little, keeping thepinhole diameter to a minimum.

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Hold the pinhole up to a light and check it for roundness and clarity. You can use your eye, amagnifier, a pair of reading glasses, etc. Be very careful i f you b r i ng that pi ece of m etalclose to you r eye, i t h as sharp edges.If the pinhole is not clean you can gently work the tipof the pin to remove any debris. Sometimes you have to sand the back and front to get acompletely clean pinhole. Clear the pinhole by blowing air through it.

Black vinyl tape is placed all around the pinhole plate before it is placed into the camera body.The tape must keep all light from coming into the camera around the edges of the pinholeplate. Set the pinhole in the center of the punched hole and press the tape down inside thecamera to make a good seal all around the plate.

The camera can now be loaded with photographic film or paper in your darkroom.A satin or matte surface paper is recommended to reduce glare inside the camera.

During an exposure the camera is pointed at a subject. To start an exposure the shutter isrotated to allow light into the camera through the pinhole. At the end of the exposure time theshutter is rotated to cover the pinhole up again.

24

The pinhol e plate is sur roun ded by black

viny l t ape and placed in the camera.

The pinhole shows through the round window

that was made with t he hole punch.

Cover the p inh ole wi th t he rotat ing shut ter .


27/43

THE BLACK and WHITE DARKROOM PROCESS

Background

Conventional photographic emulsions contain silver salts of the halide family (Cl, Br, I) that aresensitive to light. They are applied in emulsions on f ilm or paper. Since the materials are light

sensitive, they must be carefully handled in the proper light environment to preserve theirusefulness. Generally speaking, all fi lms are handled and processed in complete darkness andblack and white papers are handled and processed in darkroom safelight, which is in the red toamber range. There are exceptions for both films and papers.

When a photographic emulsion is exposed to light, a disturbance takes place in the moleculesof the silver salts. This disturbance, from point to point, is directly proportional to the intensityof the light reaching the emulsion. The resulting effect, although still invisible, is called alatent image and can last a very long time (I have developed film that was exposed forty yearspreviously and obtained excellent results.)

In black and white photography the image is brought into view by placing the exposed materialin a developer solution, which is alkaline. The developer reaction converts exposed silver salts

into elemental silver. The amount of silver formed by the reaction is also directly proportionalto the amount of light that reached the emulsion at every point. The image becomes visibleduring development.

When development reaches the desired level, the material is placed in a second solution tostop the reaction. The second solution is called a stop bath and can either be properly acidic,which neutralizes the developer, or it can be water, which dilutes the developer enough to haltchemical activity. At this point, there are two forms of silver in the emulsionsome of theoriginal silver salts that did not participate in image formation and silver metal that formed theimage.

It is necessary to remove all remaining silver salts i f the image is to be permanent. If the silversalts are left they will become exposed to light and turn dark on their own. They are removedby placing the material in a third bath called the fixer. The fixer, also acidic, dissolves all of theunused silver salts and leaves only metallic silver. After washing the fixer out of the emulsion,the image is permanent.

In conventional black and white photography a continuous gradation of gray tones from whiteto black can be formed on an image. The tones on the first image are an inversion of the tonesperceived in the physical subject. Darker tones in the image are areas of dense silver build-upand are created where an abundance of light from the subjects bright zones reached theemulsion. Lighter tones in the image are created where less light from the subject reached theemulsion. What looks bright in the subject will look dark in the image and vice-versa. This iscalled a negative, which forms on either film or paper.

Since most people preferred to see tones as they are perceived in the subject, the negativetones from the original image needed to be inverted. Passing light through the negative willinvert the tones in the negatives emulsion to positive values similar to those seen in theoriginal subject. A new piece of photographic material is positioned to capture these positivevalues and then developed to create a positive image.

If the positive is to be the same size as the negative, the positive image can be formed withouta lens using a method known as contac t p r in t i ng. This is done by placing the emulsions of thenegative and the new sheet of material in direct contact and passing light through the back ofthe negative in order to expose the positive.

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If the positive is to be a different size from the negative, the new image must be formed byprojection. The negative must be positioned above the new sheet of material and focused ontothe material by an appropriate lens before the new sheet of material is exposed.

Interestingly, a positive image can be made by taking a picture of the negative using film forprints or photographic paper. This does not hold true with slide film or digital cameras.

Safety in th e Dark room

Before you begin, take a few minutes to become familiar with safety procedures in thedarkroom. Fortunately, the Black and White process is not dangerous. Many products found in asupermarket pose more of a health hazard! Safety glasses, rubber or plastic gloves and anapron are the max imumpersonal protection recommended industrywide when working withblack and white chemistry.

Good a i r qu a l i t yis important, so if your space is small, open the door frequently to let fresh airin. A good ventilation arrangement is to have clean air coming in at the bottom of the spaceand exhaust air flowing out at the top. An exhaust fan helps a lot, but a stand-alone fan insidea small space does not.

T h e r e a r e f o u r w a y s c h em i c a l s c a n i n t e r a c t w i t h y o u ; b r ea t h i n g , s w a l l o w i n g ,

t h r o u g h t h e sk i n a n d i n t h e e y es .

Rinse with plenty of water for skin contact.

For eye contact, rinse with cool water (n o t c o l d !) for 15 minutes.

If breathing is diff icult, go out of the darkroom into the fresh air.

If chemicals are swallowed you may experience nausea, dizziness, vomiting orheadache. Induce vomiting and seek medical attention if this occurs. Photographicconcentrates should be washed off skin right away with plenty of water.

One ingredient in many photo developers, metol, is known to cause an allergic skin reaction,but this is not common. If you have any form of contact dermatitis, using photo chemicalsmight be a problem. In practice, I have not encountered one medical problem in over 20 yearsof teaching photography to students from kindergarten to adulthood. This project is designedto use small amounts of chemistry and a water stop bath for maximum safety.

Proper disposalof the small amounts of chemicals in the kit will not harm the environment.However, do no t m ix developer and f i xer d i rec t ly , as a small amount of ammonia mayform, which could prove to be unpleasant.

Darkroom Preparat ions

The items you will need for a functioning darkroom can be purchased from a photo or sciencesupplier for convenience. They can be adapted from items easy to find in local stores or theycan be made from recycled materials. This includes containers for measuring, mixing andstoring chemical solutions, containers for developing prints, a method of measuringtemperature and a device for keeping track of time.

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Metal containers should not be used with photographic chemistry with the one exception ofphoto grade stainless steel. Glass is fine but not recommended as it breaks easily. Plastics arethe best materials for photographic solutions. Polyethylene and polypropylene arerecommended. Look for these letters on the bottom of containers: HDPE, LDPE, PET(sometimes marked PETE) and PP.

Warnings

Do not store chemicals of any sort in food or drink containers! Keep chemicals well beyond the reach of children! Always provide adult supervision and guidance!

Solutions should be mixed according to the manufacturers instructions and used in the rangeof 65F to 80F. Many developers will not fully develop prints if the temperature is below thisrange. Temperatures above the range may damage papers by softening the emulsion. Thechemistry should be mixed long enough in advance to allow it to reach the right temperaturefor processing. Since this is often room temperature, you can mix the chemicals the day beforeuse and leave them in the room overnight.

Chemicals come in concentrated form, as powders or l iquids. They are mixed with water toform solutions. You will encounter both working solutions, those making direct contact withthe photo materials, or stock solutions, which are more conveniently stored and further dilutedwith water to make working solutions.

Each solution has a specific capacity for processing prints or films. This is usually stated on theconcentrates package or in the directions.

Solutions have a finite shelf life. Developers oxidize more quickly than f ixers. The shelf life ofsolutions can be extended if you remove as much air from their containers as is possible. Toaccomplish this, you can squeeze the container before placing the cap on or add glass beadsand marbles to the container in order to displace the air. Recently, a test with glass beadsshowed that a developer with a two-week shelf life expectancy was still good after ten weekswhen enough beads were placed in the container to eliminate all the air. Solutions can berefrigerated to extend their shelf life, but not frozen.

Notes on Black and Whit e Pr i nt Developers

Print developers are different from film developers. They are fairly flexible to work with interms of processing time and temperature. The minimum time would be the length of time ittakes to develop a full black on the paper. This can be determined from a fully exposed pieceof paper. Beyond the upper limit of time print density remains constant. Different papers haveslightly different ranges, but in general, a minimum of 1/2 minute and a maximum of 2 minutescan be used for developing resin-coated (RC) papers.

Dilution also plays an important role in print development. Most developer packages provide astandard dilution. Working solutions can be further diluted, which lengthens the developingtime. This is especially useful if you want to make just a few prints or if youre trying tospread a project out over several days (less concentrate is used). Additional dilution can alsomake the image contrast softer, but this depends on the particular components of thedevelopers.

Powdered developers often mix to form a stock solution first, which is further diluted to makea working solution. For Kodaks Dektol mix one part stock solution with two parts water tomake a working solution. For Ilfords Bromophen mix one part stock with three parts water.

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When print developer is exhausted, it wil l produce prints that are not dense and are discolored,or mottled or have a combination of these symptoms.

A Note on Black and Whit e Fixers

Fixers can be used for both film and paper. There are two types: Fixers labeled rapid f ixer

employ ammonium thiocyanate to dissolve silver salts and they have more capacity in additionto working more quickly. Papers should be fixed in one minute after being placed in a rapidfixer bath. Fixers without any special rapid designation use sodium thiocyanante to remove thesalts. Prints should stay in these baths for two to five minutes. A good test for fixer exhaustionis to place a small piece of unexposed black and white film in the fixer. If it does not clear inone minute then the fixer is almost saturated with silver and should be replaced.

DEMONSTRATING THE DARKROOM PROCESS

The black and white process is easy to set up and fits in a small space. This photo shows thatthe whole process can be done in a space the size of an 8" x 10" tray. The developingcontainer is made from a recycled quart-soda can. The 500 ml beakers hold developer, waterand fixer. Water for rinsing is at the side. One method of processing is to pour the solutions in

and out of the developing tube, which is more of a large motor skill. Alternatively, you canmove the paper from solution to solution using tongs which requires fine motor control. Useseparate tongs for the developer and fixer.

Here is a way to demonstrate the sensitivity of photo paper to room light as long as you k eepthe paper supp ly f r om be ing exposed to w h i te l igh t: In safelight or in total darkness take out asheet of photographic paper from the black bag. Reclose the bag to protect the remainingpaper supply from exposure. Bring the sheet of paper into room light for observation. Tear asmall piece from the paper and place it on a table. Cover half of this piece with a book or otheropaque object and leave it there for several minutes.

28

This paper was ful ly exposed to l ight b efore

placement i n th e developer solut ion.

I t developed to the maximum black tone that

the paper can produ ce.

Place a sol id object over a port i on of the

paper to demonst r ate l ight sensi t iv i ty .


31/43

Look at both sides of the larger piece of paper and identify the emulsion and the back. Theemulsion side reflects more light, has texture and usually has a creamy color. Hold the paperup to the light to check the difference in the reflectivity of each side. The emulsion will alsoabsorb moisture. If you hold your finger in one place it will feel a little bit sticky after a fewseconds. The emulsion side must face the pinhole in order to capture the image in the camera.

After you pass the paper around to the students for inspection, it will be fully exposed. In fact,the emulsion may begin to turn gray because the silver salts are light sensitive. When youremove the book from the small piece of paper you put on the table you can easily see theeffect of light sensitivity. The picture below shows a piece of paper exposed to room light bysliding the book farther along the paper every four minutes. The lightest tone is no exposure.

The next two exposures are 4 and 8 minutes. The darkest tone is 12 minutes exposure. Youcan create a human experiment with exposure time and sensitivity by putting band aids onyour skin and spending time in the sunshine!

Cut the larger piece of paper into small sections, about 1" x 2" in size. Place a piece of exposedpaper in the tube and add the developer solution. Watch the photochemical reaction until thepaper turns fully black. Pour the developer back into its own container. Next, proceed with thewater stop bath for 15 seconds, followed by the fixer for one minute. Gentle agitation shouldaccompany each step of the process. Rinse the paper thoroughly before handling.

This effectively demonstrates the process of development exactly as it will take place undersafelight conditions later, after exposures are made in the camera.

The fixer removes any silver salts left on the paper after the image is formed. This can bedemonstrated by placing the paper in the fixer f irst, rinsing thoroughly and then placing it in

29

Photo paper exposed to room l ight f or 0,

4, 8 and 12 m inu tes.

Close-up: fully exposed and developed

piece of ph otographic paper in th e

developing tube.


32/43

the developer. Reverse the process to demonstrate the role of the fixer. A more direct methodof demonstrating the role of the fixer is to place a small piece of unexposed black and whitefilm in the solution until the emulsion is dissolved and you can see through the film base.

After RC prints are fixed and rinsed they need to be washed for two to five minutes. A printwith a long wash time will last longer. If you have a batch, shuffle the prints continuously to

bring clean water to the surface of every one and exchange the water in your tray often. Verylittle washing activity takes place in RC papers after ten minutes. Wipe excess water f rom thesurface of the print with a squeegee or sponge and air dry it on a line with clothespins, on afiberglass/ nylon screen or with a hair dryer set on low. Do not stack prints with wet spotsbecause they will stick together permanently.

Loadi ng t he Camera Takes Place in Safe Light i ng Condi t i ons

At this point the darkroom safelight is turned on and white light must be extinguished. Blackand white photographic paper is the easiest material for beginning students to use as it isdesigned to be handled in safelight. Almost all other films require total darkness. It is mucheasier if the paper is precut to fit the camera. A good size for the film can camera is 1 1/ 2" x 21/ 2". This can be done with a paper cutter or scissors in the darkroom.

A single piece of paper is removed from the opaque, black bag and placed inside the cameraopposite the pinhole for exposure. The emulsion side of the paper must face the pinhole inorder to capture an image. Make sure the paper does not cover up the pinhole itself.

Reseal the black bag to safeguard the remaining paper supply. The camera must be recappedand the shutter must be rotated to cover up the pinhole. Line up the pointer on the cap withthe pinhole to make it easier to aim the camera. With the camera light tight and safely sealedthe white light may be turned on again.

30

A piece of p aper inserted properl y in the camera.

The emu lsion side must f ace the pinhole to

captur e an im age.

A camera loaded, closed and ready t o use.


33/43

For fieldwork, or if you do not have a darkroom space, these small pinhole cameras can beloaded and unloaded in a photographers black changing bag. The paper should be precut tosize and stored in separate light-tight holders, one for unexposed paper and one for exposedpaper.

I tems for ph otographing in t he f ield include camera, paper suppl y and

phot ographers changing bag. Also shown is a dayl ight f i lm developing tankmade fr om stainless steel. The paper can be moved f rom the camera int o the

developing tank i nside the changing bag for pr ocessing in dayl ight or room l ight .

A simple but ef fect ive dark room f ie ld k i t for b lack and whi t e photography: paper or f i lm,pin hole camera, dayl ight f i lm developin g tank (stainless steel), photogr aphers black changing bag,

garbage bags, developer work ing solut ion, f i xer w ork ing solut ion, lots of w ater, beakers (or other

contain ers), fu nnel, cloth espins and lin e. Paper towels, extr a buckets and soap are also handy .

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Takin g a Pict ur e Wit h t he Pin hol e Camera

The photographer selects a subject and points the pinholetowards the subject. The exact exposure time is usuallydetermined from experience, but some suggestions follow. Theshutter is rotated to allow light through the pinhole to start the

exposure and rotated to cover up the pinhole again when theexposure is finished. It really is helpful to line the pointer upwith the pinhole when loading the camera.

For good results in the beginning:

Select subjects that are easy to identify by shape;

Keep the sun behind the camera;

Look for good contrast such as light objects against a dark background or dark objectsagainst a light background;

Pick a subject with bright, medium and dark areas.

Suggested exposures for getting started with the fi lmcan pinhole camera and RC papernegatives:

Bright sun 2-4 secondsOpen shade 6-8 secondsIndoors near a window 30 secondsClassroom with fluorescent lighting 2 minutes

Bright subjects need less exposure and dark subjects require more exposure. When yourexposure is finished the paper is ready for developing in the darkroom.

In terest ing Photo Exper iments

Exposure time (a science approach):How long must an object be exposed in order to record an image? Line up several similarobjects for a photograph. Remove one object at a time at regular intervals during theexposure. Although this may seem a little impractical for small cameras because daylightexposures are so short to begin with, the solution is to make the test in subdued light orindoors. (For example, if you have a 20-second exposure place five objects in the scene andremove one object every four seconds.)

Motion (an arts approach):Photograph objects moving at different speeds. Moving vehicles and people walking by willnot be recorded in a long exposure. You need to be in the scene for about half the exposure

just to make a ghostly image. Have someone standing in one place for the first half of the

exposure and move to a different place for the second half. Have people wave their arms,shake their heads, dance, jump, etc. during the exposure.

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The pinhol e is uncovered

dur ing the exposure.


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Evaluat in g th e Negat i ve

Check the negative for good exposure. If its too dark, the exposure was too long(overexposed). If its too light, the exposure was too short (underexposed). Adjust theexposure time to get the results you want. If its all black you might have a light leak in thecamera or darkroom. The pinhole could be uncovered or the top could be loose. Put black tapearound the seal if you cant get the top on tightly.

33

The f i r st im age from the camera is a

negative (top). Light objects appear

dark, and dark obj ects appear l ight.

Many posit iv e print s (bott om) can be

made fr om on e single negat iv e.

A good negat iv e, l ik e this one of a coff ee pot

s i t t ing on a windowsi l l , wi l l have detai ls that

are easy to see in th e areas of th e pictu re th at

are most imp ortant t o you. Once you havedetermined a good exposure in a part icular

l ight condi t i on you can use i t a l l the t im e. I t

only t akes a few tr i es to m aster each ty pe of

l igh t. Keep good notes!


36/43

CONTACT PRINTING: How t o Make Posit iv e Pri nt s

In darkroom safelight, the negative is placed in contact with a new piece of paper, emulsion toemulsion. The exposure is made by passing white light through the back of the negative to thenew paper. This reverses the tones to make a positive print. You can also use th is cont actp r in t in g pr ocedur e to ma ke pr in t s f r om an y developed f i lm s you a l r eady ha ve (colo r or b lack

and w h i te ) and t o mak e new paper n ega t i ves f r om o ld f am i l y pho togr aph s or even s l ides!

Light Sources: A white 15-watt bulb placed in a light fixture two to four feet from the paperworks well, but a 25- or 30-watt bulb can also be used. Use the room lights, small lamp orflashlight. For safety, make sure there is a switch to turn the bulb on and off!

Exposures are often less than 30 seconds and should be tested for best results. Similarexposures can be used for all negatives with similar densities. You can adjust the lightintensity by moving the bulb nearer to or farther from the paper, blocking some of the lightwith thin white paper, changing the bulb, etc.

Contact printing can be done without glass by wetting the two pieces of paper so they sticktogether during the exposure. In safelight, soak the negative and new piece of paper in water

and remove excess water with a sponge or squeegee. Then place the papers emulsion toemulsion. Rememberthe light must first pass through the back of the negative during theexposure.

Test in g for cor rect exposures

When using small pieces of paper, you should make different exposures on individual sheets ofpaper to find the best exposure for your positive. With larger negatives a test strip allows youto get several exposures on one sheet of paper. Be sure to test the most important part of theimage.

For example, lets say you want to test exposures up to 16 seconds long. Use four separatepieces of small paper and give the first piece a 4-second exposure, the second piece an 8-second exposure, the third piece a 12-second exposure and the last piece a 16-secondexposure.

Or, to make a test strip for a larger negative, set up the contact print and make a 4-secondexposure over the entire image. Then cover the first 1/ 4 of the paper with opaque blockingmaterial (mat board, black plastic, cardboard, etc). Now make another 4-second exposure. Thepaper under the light blocker has a 4-second exposure and the rest of the image has 8 seconds.

Now slide the light blocker along to cover the first 1/ 2 of the paper. Make another 4-secondexposure. Finally, slide the light blocker along to cover 3/ 4 of the paper and make the last 4-second exposure. You will have created exposure bands of 4, 8, 12 and 16 seconds. Developyour test strip and check the results.

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Evaluat in g th e Test

It might take a few tries to get a good test but once successful it will always be easy. Here aresome typical results:

t oo dark (overexposed), reduce exposure: use less exposure time, move the light farther

away, use a less powerful bulb, block some of the light, etc.

l ooks r i gh t (properly exposed), make your final print using the exposure that looks best (orestimate a time in-between bands)

too l ight (underexposed), increase exposure: use more exposure time, move the light closer,use a more powerful bulb

Once a good exposure is found for a particular negative the final positive print is made by

contact printing.

Take out a new piece of paper and place it emulsion up on the flat surface. Then place thenegative, emulsion down, on the new piece of paper. Put a sheet of glass over them and makeone exposure using the time you liked best from the test. The same time will work well forother negatives with similar density. Keep a record of your work it will save lots of effort infuture printing sessions.

35

Thi s test stri p show s a series of 4-second exposur es on on e piece of p aper. The bands are 4, 8, 12

and 16 seconds. Choose the one that look s best (or a t im e in between the bands) to expose the

whole pr int . The 12-second exposur e was used here to m ake the f inal pr int . I t pr ovided a pleasing

range of t ones.

On the r ight , the posi t ive image of th e cof f ee pot s i t t ing on a windowsi l l l ooks good.


38/43

ADDIT IONAL PHOTO ACTIVIT IES

Photograms (basic)

Photogramsare a kind of image made by placing objects directly on the paper in the darkroomand then exposing the paper to white light. The light can come from above (or from the side to

create shadow effects). The print will show the shape and translucency of things you placed onthe paper. Objects collected from nature or found around the house make great images.Photogram exposures are usually pretty shortuse just enough light to create a black tone onthe uncovered part of the paper.

Add ing co lo r to p r in t s (in t e rmed iate )

Some black and white papers have color bases, such as red, blue or silver, so the color isautomatic. Other methods of coloring that take place after the print is made include toningand hand coloring with photo oils and pencils. Try toning prints in coffee or grape juice. Paintsand markers can be applied to the print. Sew buttons on the prints. Anything goes!

Changing pr in t cont r ast (advanced)

Many papers have built in variable contrast. They are described with terms like VC, multigradeor polycontrast on the package. Standard multicontrast filters can be used to change printcontrast in the darkroom. You place the fi lters between the light source and the paper. Lownumbered filters make soft, low-contrast prints. Higher numbers increase contrast. You canalso place these fi lters in the camera, behind the pinhole, to change a negatives contrast,which requires an increase in exposure time and should be tested.

Matchin g exposur es to a l ight meter (advanced)

If you have a light meter (hand held or in camera) you can make an accurate exposure chart forany photo material you work with. Take your meter along and record the meter reading for thesubject you are going to photograph with the pinhole camera. Match up good pinholeexposures to your meter readings.

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DISPOSAL OF THE CHEMICALS

Used developer and water can be flushed down the drain as you exhaust it. Save the used fixerin a separate container; it contains silver, a heavy metal. Silver from photography is quitestable but its better to keep metals out of the environment, so a simple silver recoverydemonstration follows. Used fixer, after the silver is removed, can be flushed down the drain.

If you are on a municipal waste system, silver and other metals are removed from the liquidwaste at the processing plant. If you are on a home septic system, it is widely recommendedthat the total amount of photography chemicals plus photo wash water be less than 10%ofyour total daily waste disposal. Check your local regulations.

Sil ver Recovery D emon str at io n (an excel l ent c lass demo!)

The presence of silver in used fixer can be shown with a short piece of copper. Scrape it downto bright metal with steel wool, sandpaper, etc. and place it in a small amount of well-usedfixer. You should observe the silver building up on the wire in a minute or two. Rinse withwater. (You can reuse the same wire many times if you scrape off the silver.) New fixersolutions have no accumulated silver, so this test will show no silver buildup in unused fixer.

A small amount of steel wool provides a simple method of recovering the silver from usedfixer, making the fixer safer for disposal. Observe the condition of the new steel wool. Placefour grams of steel wool (thats about the amount that you can squeeze into a 35 mm filmcanister) per liter of used fixer in a plastic container. If you tie a string around the steel woolyou can lift it from time to time in order to see the silver building up. You should see somesilver quickly, usually in less than a minute. The silver here will appear black. Since the silverand iron are trading places you might see some rust in the solution. This is normal and it can be

safely flushed down your drain (or the solution can be filtered).

If you leave the steel wool in the solution for 24 hours, the silver concentration will be reducedfrom approximately 5,000 parts per mill ion to the range of 0 to 5 parts per million! When youtest with copper after silver recovery and the copper has no silver buildup after 20 minutes,you have achieved a silver level of 0 to 5 parts per mil lion (5 ppm is the federal EPA standard).If no silver builds up on the copper after one hour, you have reached a 0 to 2 parts per mil lionsilver level. Rinse and dry the metals. The recovered silver is very stable and safe to handle,

just like jewelry. You can save it or place it in your waste basket.

Many thanks for helping to preserve a clean and healthy environment. Its a smart thing to do!

37

A copper nai l is p laced in u sedf ixer solut ion t o demonst rate the

presence of si lver in t he f ixer.

On the lef t is a new copper nai lr ight out of the box. The nai l on

the r ight is coated wi th s i lver

af ter a short im mersion in the

used f ixer solut ion .


40/43

Materials

The things you need for the camera obscura project are very common and can usually be foundlocally.

Materials to cover the windows:

Recycled cardboard boxes, black plastic (local hardware store) or any other materialsyou can find

Duct tape and black vinyl electrical tape

Scissors

X-acto knife (optional)

Materials to make apertures include:

Recycled soda cans

Thick aluminum baking pans or pie tins (recycled or supermarket)

Paper

Materials to make a viewing screen include:

Plain white paper

Tracing paper

Drafting film

Thin, white plastic bags

Cardboard to make a frame for the screen

A simple magnifying glass can be used as a lens

Thin gs you need f or p i nhol e photography are a mi x of easy to f i nd l ocal i t ems

and some i tems f r om a photograph ic supp l ie r .

Materials to make a pinhole camera include:

Recycled black film canisters

Aluminum for the pinhole plate (use baking strength, not foil)

Sewing needles (#9 or #10)

Fine sand paper (400 grit)

Black vinyl electrical tape

Scissors

One-hole punch

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Materials to set up a darkroom include:

Darkroom safelight

Container for mixing chemicals (plastic or glass measuring cups, beakers, graduatedcylinders)

Stirring rod (plastic straw works well) Containers for storing chemicals (recycled plastic HDPE, PP, PETE)

Containers for processing the prints (plastic as above)

Squeegee or sponge

Thin line and clothespins for drying prints

Photographic supplies:

Black and white photographic paper

5" x 7" RC paper, satin or matte surface

Avoid papers that have the manufacturers name on the back (like Kodak)

because it will show up on the final prints

Black and white paper developer (liquid concentrate)

Black and white fixer (liquid concentrate)

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Resources

Phot ographi c sour ces

Starlight Cameras

www.paintcancamera.cominnovative pinhole cameras and darkroom kits with complete instructionsoffer complimentary pinhole cameras to teachers

Unique Photohttp:/ / www.netphotostore.com/

full line supplier

Freestyle Photo Supplieshttp:/ / www.freestylesalesco.com/

full line supplier

LINKS

Camera Obscur a

The Camera Obscura: Aristotle to Zahnhttp:/ / www.acmi.net.au/ AIC/ CAMERA_OBSCURA.html

The Magic Mirror of Life http:/ / brightbytes.com/cosite/ cohome.html

Pinhole Sunspotsor, Could the Ancient Egyptians Have Observed Sunspots?http:/ / users.erols.com/ njastro/ barry/ bar-page/ pinhole.htm

Views of a Solar Eclipse http:/ / www.astro.indiana.edu/ solar/

Pinhole Photography

Pinhole Visions - http:/ / www.pinhole.com

Pinhole Discussion List -http:/ / www.pinhole.com/discussion/

Handmade Photographic Images by George L Smyth ???http:/ / members.home.net/hmpi/Pinhole/ Articles/FAQ/pin_faq.htm

Worldwide Pinhole Photography Day - http:/ / www.pinholeday.org/

Pinhole Resource - http:// www.pinholeresource.com/

Photography with a Pinhole Camera - http:/ / acept.la.asu.edu/ PiN/ rdg/camera/camera.shtml

Agfas Black & White Darkroom Course - http:/ / www.agfanet.com/en/ cafe/ photocourse/

Ilford Teachers Lounge - http:/ / www.ilford.com/html/us_english/ teachers_lounge/ index.html

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References

Horenstein, H. Black an d Whi te Photogr aph y : A Bas ic Man ua l, 1983, Bulfinch Press, Boston.Paperback - 229 pages 2nd Rev edition, ISBN: 0316373141

James, C. The Book of Al t ern at i ve Phot ogr aph ic Pr ocesses, 2001, Delmar Publishers, Florence.Paperback - 400 pages 1st edition, ISBN: 0766820777

Renner, E. Pinh o le Photogr aph y: Rediscovering a Historic Technique, 1999, Focal Press,Woburn.Paperback - 192 pages 2nd edition, ISBN: 0240803507

Schull, J. The Beg inner s Gu ide t o Pinh o le Photogr aph y, 1999, Amherst Media, Buffalo.Paperback - 80 pages, ISBN: 0936262702

Pin hol e Jour nal (periodical published 3 times a year)http:/ / www.pinholeresource.com/pinholejournal.html

Fro m Pinh ole to Pixel(CD)Peggy Joneshttp:// www.pinholeresource.com/ books.html

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camera obscura

Documents