front yard ccd astrophotography january 11, 2007
TRANSCRIPT
Front Yard CCD Front Yard CCD AstrophotographAstrophotograph
yyJanuary 11, 2007January 11, 2007
My Recommendations for My Recommendations for startingstarting
Learn!Learn! Purchase/read “The New CCD Astronomy” by Purchase/read “The New CCD Astronomy” by
Ron WodaskiRon Wodaski Purchase/read “Photoshop for Purchase/read “Photoshop for
Astrophotographers” by Jerry LodrigussAstrophotographers” by Jerry Lodriguss SBIG users groupSBIG users group Websites: Websites:
http://www.rc-astro.com/http://www.rc-astro.com/ (Russell Croman) (Russell Croman) http://www.robgendlerastropics.com/http://www.robgendlerastropics.com/ (Robert (Robert
Gendler)Gendler) http://www.mistisoftware.com/astronomy/http://www.mistisoftware.com/astronomy/ (Jim Misti) (Jim Misti)
Club expert/mentor (John Boudreau)Club expert/mentor (John Boudreau) Webcam and planets/moonWebcam and planets/moon
What can I do?What can I do? Start: Photographs of the moon and Start: Photographs of the moon and
planetsplanets WebcamWebcam RegistaxRegistax Good scopeGood scope Moderate tracking abilityModerate tracking ability Works from light polluted areas (bright Works from light polluted areas (bright
objects)objects) Good results with minimal investment Good results with minimal investment
obtained from stacking hundreds of obtained from stacking hundreds of imagesimages
What can I do?What can I do? Deep-sky objects from Andover Deep-sky objects from Andover
Light pollution effects photograph quality Light pollution effects photograph quality (increased sky background noise )(increased sky background noise )
Long exposure times >5 hours/objectLong exposure times >5 hours/object Practical implications of seeing conditions Practical implications of seeing conditions Good to high level quality equipment Good to high level quality equipment
produce better quality photos produce better quality photos (expense/investment)(expense/investment)
Produce good quality photographsProduce good quality photographs Digital Development Processing algorithms Digital Development Processing algorithms
(DDP) and photo-processing “workflows” (DDP) and photo-processing “workflows” can correct many problems can correct many problems
Deep Sky CCD – Mount Deep Sky CCD – Mount SelectionSelection
Spend 60% of Spend 60% of money on Mountmoney on Mount Periodic error Periodic error
correction (PEC)correction (PEC) 30 sec exposure less 30 sec exposure less
importantimportant 30 min exposure 30 min exposure
requires good PEC requires good PEC and tracking (auto and tracking (auto guiding)guiding)
Telescope focal length Telescope focal length significant factorsignificant factor
Accurate auto-Accurate auto-guidingguiding
Worm-gear designWorm-gear design Motor designMotor design
Deep Sky-Mount Deep Sky-Mount SuggestionsSuggestions
I use Astro-Physics 900 GTOI use Astro-Physics 900 GTO Mounts others have usedMounts others have used
Losmandy (G11 and Titan)Losmandy (G11 and Titan) TakahashiTakahashi ParamountParamount Mountain InstrumentsMountain Instruments Meade (RX400, LX200)Meade (RX400, LX200) Celestron (CGE)Celestron (CGE)
Learn characteristics of Learn characteristics of your mount-Auto-guidingyour mount-Auto-guiding
BalanceBalance “ “Slight” east Slight” east
weightingweighting Appropriate selection Appropriate selection
of weights to center of weights to center moment armsmoment arms
Adjust worm gear / Adjust worm gear / meshmesh
Software or mount Software or mount firmware PEC firmware PEC correctioncorrection
Deep Sky CCD – Telescope Focal Length Deep Sky CCD – Telescope Focal Length (ref: “The New CCD Astronomy”)(ref: “The New CCD Astronomy”)
LengtLengthh
SeeingSeeing ApertApertureure
TargetTargetss
FlexibiliFlexibilityty
400-400-800800
RarelyRarely 3-6”3-6” Big Big targetstargets
Good-add Good-add BarlowBarlow
800-800-15001500
A A consideratconsiderat
ionion
5-10”5-10” More More targetstargets
Good if Good if focal focal
reducers reducers availableavailable
1500-1500-20002000
Always Always mattersmatters
8-16”8-16” Many Many more more
targetstargets
Good if Good if focal focal
reducers reducers availableavailable
Deep Sky – Telescope Deep Sky – Telescope SelectionSelection
Better optical quality provides sharp correct Better optical quality provides sharp correct color round starscolor round stars
Recommend match telescope with CCD Recommend match telescope with CCD camera (ref: camera (ref: http://www.sbig.com/sbwhtmls/online.htm)http://www.sbig.com/sbwhtmls/online.htm)
Telescope Field of ViewTelescope Field of View CCD chip sizeCCD chip size CCD chip pixel sizeCCD chip pixel size
Flat field neededFlat field needed Adapter for telescope (field flattener)Adapter for telescope (field flattener) Optical design with flat field (modified Petzval)Optical design with flat field (modified Petzval) Astro-Physics sells adapter for SBIG cameras that fits in Astro-Physics sells adapter for SBIG cameras that fits in
front of camera (front of camera (http://www.astro-physics.com/http://www.astro-physics.com/ - -CCD CCD Telecompressor (CCDT67))Telecompressor (CCDT67))
My Deep Sky Telescope My Deep Sky Telescope SelectionSelection
Takahashi FSQ 106 NTakahashi FSQ 106 N APO fluorite refractorAPO fluorite refractor Modified Petzval - 88mm Modified Petzval - 88mm
circle flat field imagecircle flat field image 4” focuser4” focuser 36036000 camera angle camera angle
adjusteradjuster Aperture 106mmAperture 106mm Focal length 530mmFocal length 530mm Compatible with large Compatible with large
CCD chips currently on CCD chips currently on marketmarket
Modified Petzval DesignModified Petzval Design
Deep Sky-CCD Camera Deep Sky-CCD Camera SelectionSelection
Anti-Blooming Gate (ABG)Anti-Blooming Gate (ABG) Easier to useEasier to use Less sensitiveLess sensitive
Non-Anti-Blooming Gate Non-Anti-Blooming Gate (NABG)(NABG) More sensitiveMore sensitive Careful planning of exposure time Careful planning of exposure time
needed (experience)needed (experience) Minor blooming can be fixedMinor blooming can be fixed
SoftwareSoftware Photo Processing takes more timePhoto Processing takes more time
Camera DesignsCamera Designs One-shot color cameraOne-shot color camera
Filters located on chip – no filter wheelFilters located on chip – no filter wheel Easy to use –good example is planets via Easy to use –good example is planets via
webcamwebcam Less flexibleLess flexible
Black and white with filter wheelBlack and white with filter wheel Flexible – can use many different types of Flexible – can use many different types of
filtersfilters More complex to photo-process to color imageMore complex to photo-process to color image Better control over quality and composition of Better control over quality and composition of
color imagecolor image
Match Camera, Telescope Match Camera, Telescope and Mountand Mount
Telescope focal length (ref: Telescope focal length (ref: http://www.sbig.com/sbwhtmls/online.hthttp://www.sbig.com/sbwhtmls/online.htm)m)
Ability of mount to track and guide Ability of mount to track and guide effectivelyeffectively Compensate for longer exposure times Compensate for longer exposure times
needed for ABG needed for ABG NABG better if short exposure times are NABG better if short exposure times are
needed to match mount capabilityneeded to match mount capability Light pollution-NABG offers advantageLight pollution-NABG offers advantage
Auto-guiding optionsAuto-guiding options
Separate CCD and Separate CCD and scope for guidingscope for guiding
Camera with built-in Camera with built-in guide chip (Santa guide chip (Santa Barbara Instrument Barbara Instrument Group, Inc (SBIG))Group, Inc (SBIG))
Don’t guideDon’t guide WebcamWebcam Short exposures (30 Short exposures (30
sec) and stack 50 – sec) and stack 50 – 200 images200 images
Improve signal to Improve signal to noise noise
My Camera Selection SBIG My Camera Selection SBIG ST-2000XM (ref: SBIG ST-2000XM (ref: SBIG
website)website)CCD
CCD Kodak KAI-2001M + TI TC-237
Pixel Array 1600 x 1200 pixels CCD Size 11.8 x 8.9 mm
Total Pixels 2 million Pixel Size 7.4 x 7.4 microns square
Full Well Capacity ~45,000 e- unbinned ~90,000 e- binned
Dark Current 2.5e-/pixel/sec at 0 deg. C. Antiblooming Standard
Readout Specifications
Shutter Electromechanical Exposure 0.001 to 3600 seconds
Correlated Double Sampling Yes A/D Converter 16 bits
A/D Gain 0.18e-/ADU unbinned Read Noise 13.5e- rms
Binning Modes 1 x 1, 2 x 2, 3 x 3 Pixel Digitization Rate ~ 425kps Full Frame Download ~ 4.5 seconds
My Camera Selection SBIG My Camera Selection SBIG ST-2000XM (ref: SBIG ST-2000XM (ref: SBIG
website)website)
My Camera Selection SBIG My Camera Selection SBIG ST-2000XMST-2000XM
My Camera Selection SBIG ST-My Camera Selection SBIG ST-2000XM2000XM
Photo Session-Focus Photo Session-Focus
Maxim DL Maxim DL SoftwareSoftware View of star size View of star size
and number of and number of small faint starssmall faint stars
Optimize for Optimize for maximum intensity maximum intensity for star (signal)for star (signal)
Optimize for Full Optimize for Full Width at Half Width at Half Maximum (FWHM)Maximum (FWHM)
Focus Zen-Maxim DLFocus Zen-Maxim DL Gross focus with imaging chip at 2 binGross focus with imaging chip at 2 bin Fine focus small selected area of CCD at Fine focus small selected area of CCD at
full resolution 1binfull resolution 1bin Set exposure time at >2 sec so that Set exposure time at >2 sec so that
changes in seeing are not major factorchanges in seeing are not major factor Watch temperatureWatch temperature
FSQ in focus range is 35 micronsFSQ in focus range is 35 microns Temperature change >2Temperature change >200F causes stars to F causes stars to
bloat and loss in signalbloat and loss in signal Focus-aid: Plan to purchase Robo-FocusFocus-aid: Plan to purchase Robo-Focus
Photo Session – ObjectPhoto Session – Object Study objectStudy object
Size (mosaic will need to be planned)Size (mosaic will need to be planned) ColorColor BrightnessBrightness
Globular cluster uniformGlobular cluster uniform Galaxy Bright core faint outer regionGalaxy Bright core faint outer region Nebula have strong narrow band emissionsNebula have strong narrow band emissions
Filter selectionFilter selection Luminance for white light detail (L)Luminance for white light detail (L) Red, Blue, Green (RGB) for colorRed, Blue, Green (RGB) for color Halpha (656.26 nm) narrow band filter for red nebulaHalpha (656.26 nm) narrow band filter for red nebula Narrow band filter compositesNarrow band filter composites
Match filters to object and combine (LRGB, Match filters to object and combine (LRGB, RRGB, HalphaGB, LHalphaRGB)RRGB, HalphaGB, LHalphaRGB)
Photo Session – Frame Photo Session – Frame and Lockand Lock
Locate objectLocate object Roughly frame object on image chipRoughly frame object on image chip Find suitable guide-star (>25000 Find suitable guide-star (>25000
ADU for filter transmitting lowest ADU for filter transmitting lowest signal – Halpha)signal – Halpha)
Finalize object framingFinalize object framing Lock on guide starLock on guide star Auto-guideAuto-guide
Photo Session-CCD Camera Photo Session-CCD Camera Correction FramesCorrection Frames
Dark Frames. Dark Frames. Correct for dark Correct for dark current that current that increases as a increases as a function of time and function of time and temperature temperature (Thermal signal)(Thermal signal)
Bias Frames. Bias Bias Frames. Bias that occurs when that occurs when pixel is read by pixel is read by camera (Zero light camera (Zero light exposure)exposure)
Photo Session – Flat Field Photo Session – Flat Field Correction for OpticsCorrection for Optics
Taking Flat Field FramesTaking Flat Field Frames