1. DSLR AstrophotograpHy…. My way

2. My camera

3. Why Canon? Provides RAW files
Not directly useable as an image
“Digital negatives”… unprocessed readout of pixels
Well suited for dark subtracting and flat fielding… not true of Nikon
Canon uses CMOS (complementary metal oxide semiconductor) sensor
Less sensitive than CCD, but cheaper to make
Generally consumes less power than CCDs
Provides excellent color

4. Creating a color digital image

5. One shot color (Bayer Matrix)
Filtered sensors convert photons to electrons which can be measured

6. Bryce Bayer ( )

7. How color is created
Debayering the matrix… greyscale data converted to RGB image
Each pixel contributes to the luminance image which gives detail

8. Processing after demosaIcing
Irreversible processes best done on a computer and not in the camera

9. Other reasons to use Canon
Software readily available
Acquisition (Images Plus, Backyard EOS, Nebulosity, DigiCamControl)
Processing (Images Plus, PixInsight, Nebulosity, Deep Sky Stacker)
Gain from the experience of others
Yahoo Group Digital Astro
Yahoo Group DSLR Astro Image Processing
Cloudy Nights DSLR & Digital Camera Astro Imaging & Processing
Jerry Lodriguss CCD books are excellent and website
Books, adaptors, modifications, etc., are widely available

10. Why modify the canon sensor?
Stock IR cut filter limits Ha response of sensor

11. Modified camera is a must

12. Downsides of modifying camera
Must use custom white balance
Auto mode will not work with custom white balance in older Canons… must use P or M mode
Canon warranty is void and they will not service the camera
Cost is $200 - $300 (Hutech, Hap Griffin, Gary Honis)

13. Comparing Canon Cameras

14. APS-C sensor (advanced photo system)

15. Lenses and telescopes that I use
17-40mm f/4 Canon
85mm f/1.8 Canon (image scale 13.5 arcsec/pixel)
200mm f/2.8 Canon (IS 5.4)
Borg 77ED refractor, f/5.5 (IS 2.5)
TAK FSQ 106 refractor, f/5 (IS 2)
TEC 140 refractor, f/7 (IS 1.1)
Importance of image scale… try to stay >2

16. Connecting to the telescope

17. Image acquisition
Important to use a computer because it gives the best focus
Images Plus Camera Control
Many features… DSLR (Canon and Nikon), CCD, video
Autofocus control for motorized focusers; temperature compensation
$240, includes image processing software
Very good video tutorials
Backyard EOS
Only for Canon cameras
Manual focus aid plus framing aid, drift alignment, video, eclipse mode
Only $30

18. Backyard EOS focusing

19. Typical exposures Usually stop down lenses a couple of stops
Always use ISO1600 (never go below ISO800)
Always collect RAW images (optional JPEG or TIFF)
Usually 3-4 minute unguided exposures
Total exposure time usually 1-2 hours ( exposures)
Usually take 5-10 dark exposures, but no flats

20. Image processing Images Plus
Dark subtraction to reduce sensor noise (no flats)
Debayering conversion to color FITS
Grading
File conversion to 16-bit TIFF
Could do everything in Images Plus

21. Registar CCDStack PHOTOSHOP (CS5)
Use for aligning and combining (usually median)
Fool-proof and very flexible; mosaics; aligning different formats
CCDStack
Use for digital development (non-linear stretch)
Creation of luminance image
Deconvolution of luminance
PHOTOSHOP (CS5)
Use LRGB method (Adam Block)
Carboni’s Astronomy Tools, Gradient Xterminator, Noise Ninja, HLVG

22. Monitor calibration
Important if others are looking at your images online
Spyder4 Express (~$100)

23. Slides on website