FotoGangsta | Photography 101

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  • 7/31/2019 FotoGangsta | Photography 101

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    https://www.facebook.com/FotoGangstaPhoto tips!

    Lens types:

    Telephoto, wide-angle, zoom and prime. Prime lens (Fixed lens)- used by portrait photographers- have wider maximum apertures,

    making them faster

    Digital zoom: crops into the center area of the captured frame, effectively enlarging the pixels.

    Focal length: Distance between lens and image sensor- or the amount of magnification. When you

    set a fire with a magnifying glass, the distance between the magnifying glass and paper is the magnifying

    glass' focal length. Camera lenses are more complicated, but it's the same measurement. E.g.: In Canon

    50mm f1.8 lens, 50 mm is the focal length.

    Aperture: The aperture is the opening in the lens (created by an adjustable iris or diaphragm) that

    allows light to pass through. The aperture is measured in f-stops. An f-stop is a ratio of the focal length

    of the lens to the diameter of the opening of the aperture. The larger the numerical value of the f-stop,

    the smaller the opening of the aperture. The larger the aperture, the faster the lens. The larger the

    aperture, the more light is allowed to pass through the lens. f/4 means that the diameter of our

    magnifying glass is 1/4 of its focal length. f/2 means a lens is half as big around as its focal length, or

    twice as big around as an f/4 lens of the same focal length. E.g.: In Canon 50mm f1.8 lens, f1.8 is the

    aperture (lens diameter can be calculated to be 28mm). On the lenses, its marked as 1:1.8.

    Shutter speed: Shutter speed refers to the amount of time the shutter is open or the digital image

    sensor is activated. The Shutter speeds are displayed as fractions of a second, such as 1/8 or 1/250.

    A fast-moving object, such as a car, tends to blur when shot with a slow shutter speed like 1/8.On the other hand, a fast shutter speed, such as 1/1000, appears to freeze the blades of a

    helicopter while its flying.

    The relationship between the aperture and shutter is known as reciprocity. Reciprocity gives thephotographer control over the depth of field of the image, which controls the area of the image

    that remains in focus.

    Depth of field: The area of an image that is in focus. The aperture setting (f-stop), combined with

    the focal length of the lens, determines the depth of field of an image.

    The larger aperture settings, combined with the long focal lengths of telephoto lenses, can limitthe depth of field to a small area. Small aperture settings, combined with long focal lengths,

    make objects in the foreground and background seem closer together.

    Exposure of the image: Determined by the combination of shutter speed and the opening of the

    aperture.

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    Lenss Speed: Determined by the maximum amount of light the lens is capable of transmittingthe

    largest f-stop value (smallest number) (larger the aperture, the faster the lens). When a lens is capable

    of transmitting more light than other lenses of the same focal length, that lens is referred to as fast. Fast

    lenses allow photographers to shoot at higher shutter speeds in low-light conditions. For example,

    lenses with maximum f-stop values between 1.0 and 2.8 are considered fast.

    ISO: Light-sensitivity of the camera (image sensor). Traditionally, the International Standards

    Organization (ISO) has provided a benchmark rating of the relative sensitivity of film. The higher the ISO

    rating, the more light sensitive a particular film is. Higher ISO films require less light to record an image.

    The ISO rating has been redefined for digital cameras, indicating the image sensors sensitivity to light.

    Most DSLRs have ISO settings from 100 to 3200 ISO. Unfortunately, at higher ISO settings (400 ISO and

    above), some cameras have difficulty maintaining consistent exposure for every single pixel in the

    image, resulting in digital noise. You can reduce digital noise by taking your photographs at ISO settings

    between 100 and 400.

    Digital Image Sensor: consists of millions of individual elements capable of capturing light. Thelight-sensitive elements transform light energy to voltage values based on the intensity of the light. The

    voltage values are then converted to digital data by an analog-to-digital converter (ADC) chip.

    Types:o Charge-coupled device (CCD)o Complementary metal oxide semiconductor (CMOS) (higher rate of data transfer to the

    storage device; used in professional DSLRs)

    Resolution:An images resolution is determined by the images pixel count and the bit depth ofeach

    pixel.

    Megapixels: A cameras resolution capability is measured in megapixels. This measurement isbased on the number of millions of pixels of image information that can be captured by the

    light-sensitive elements on the digital image sensor. Thus, a 15 megapixel camera is capable of

    capturing 15 million pixels of information.

    Bit Depth: Bit depth describes the number of tonal values or shades of a color each channel(there are 3 color channels- RGB) in a pixel is capable of displaying. Increasing the bit depth of

    color channels in an images pixels exponentially increases the number of colors each pixel can

    express. DSLR cameras usually have two settings, allowing the photographer to shoot an 8-bit

    JPEG file (with 8 bits per color channel) or a 16-bit RAW image file (with 12 to 14 bits per color

    channel).

    A cameras resolution is calculated by the number of megapixels (millions of pixels) its digitalimage sensor is capable of capturing.

    A displays resolution is expressed in pixels per inch (ppi) or as a maximum dimension, such as1920 x 1280 pixels.

    A printers maximum resolution is expressed in dots per inch (dpi)the number of dots it canplace within a square inch of paper

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    RAW:A cameras RAW file is an un-interpreted, bit-for-bit digital image recorded by the camera when

    the image is captured. Along with the pixels in the image, the RAW file also contains data about how the

    image was shot, such as the time of day, the exposure settings, and the camera and lens type. This

    information is also known as metadata (EXIF). The JPEG format is limited to 8 bits per color channel.

    RAW images store 16 bits per channel. Increased bit depth allows for more color-correction head

    room.

    Red-eye: Phenomenon where people have glowing red eyes in photographs. This is caused by the

    close proximity of the flash (especially built-in flash) to the camera lens, which causes light from the

    subject to be reflected directly back at the camera. When the flash fires, the light reflects off the blood

    in the capillaries in the back of the subjects eyes and back into the camera lens. People with blue eyes

    are particularly susceptible to the red-eye phenomenon because they have less pigment to absorb the

    light.

    Notables:

    Most interchangeable lenses were originally created and rated for the 35 mm film plane oftraditional SLRs. So if the size of an image sensor is smaller than 35mm, this results in some of

    the light refracted by the lens to be missed by the sensor at its borders. This results in

    magnification of real focal length of a camera. Shooting wide-angle images becomes increasingly difficult when using cameras with smaller

    digital image sensors. For example, if your digital image sensor is 24 mm, you require a lens with

    a focal length less than 24 mm to achieve a wide-angle view.

    Wider apertures allow for brighter images in low-light situations, as well as greater control overdepth of field (wider aperturesshallow depth of field).

    Telephoto lenses (with long focal lengths) tend to have shallow focus when the aperture isopened all the way, limiting the depth of field of an image. Wide-angle lenses (with short focal

    lengths) tend to create images with great depth of field regardless of the aperture setting.

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