1 / 23

DSLR AstrophotograpHy …. My way

DSLR AstrophotograpHy …. My way. My camera. 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

nemo
Download Presentation

DSLR AstrophotograpHy …. My way

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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 http://www.cambridgeincolour.com/tutorials/camera-sensors.htm

  6. Bryce Bayer (1929-2012) http://image-sensors-world.blogspot.com/2012/11/bruce-bayer-died.html

  7. How color is created Debayering the matrix… greyscale data converted to RGB image Each pixel contributes to the luminance image which gives detail http://www.cambridgeincolour.com/tutorials/camera-sensors.htm

  8. Processing after demosaIcing Irreversible processes best done on a computer and not in the camera http://www.cambridgeincolour.com/tutorials/raw-file-format.htm

  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 (15-30 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 • 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 • Deconvolutionof 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 www.geoandpat.com

More Related