
Let’s Define ‘BEST’ Camera should be relatively easy to use, almost obvious & familiar Camera should be versatile and able to do it all, providing opportunities to explore all types of astro-imaging…& more Software to control camera and process images should be relatively inexpensive and, where possible, multi-platform compatible: Windows & Mac Canon EOS Digital Single Lens Reflex Camera Full Frame (36 x 24 mm) & APS-C (22.5 x 15mm) Full frame great for wide-angle, expansive images (Milky Way & meteor showers) APS-C less sensitive to optical aberrations at edge of field; less than ‘perfect’ optics will yield great images APS-C pixel size is smaller and more optimal for common amateur optical systems APS-C cost less than full frame cameras Crop 640x480 video mode or equivalent Takes 640x480 pixel center of image chip and treats as full-resolution video/webcam Great for high-resolution lunar, solar and planetary imaging EOS Utility Powerful camera control software - Windows and Mac My Cameras 2004 to 2013 Canon EOS 20D/20Da Canon EOS 6D Canon EOS 60Da Full Frame APS-C 5472 x 3648 (20 Mpixel) 5184 x 3456 (17.9 Mpixel) 6.54 µm 4.3 µm Nyquist optimum = f/24 Nyquist optimum = f/16 ISO 100 - 25,600 ISO 100 - 6,400 JPEG (8-bit) & CR2 (14-bit) JPEG (8-bit) & CR2 (14-bit) Crop 640 x 480 video mode Extended IR filter for enhanced H-α Wide-angle imaging only All other imaging Timer Remote Controller Single shot remote release - prevents camera vibration and image blurring Full camera control programmer (intervalometer) controls time between exposures, exposure length and number of exposures - without a computer Self-timer to delay sequence after activation Exposures saved onto camera storage card Cost < $100 For 7 years used as only means to control camera for all deep-sky imaging - no computer in field Still using it after 14 years Does not control video mode Highly recommended Image Processing Software Adobe Photoshop (expensive), Ver. 2.5, 3.0, 4.0, 5.5, CS, CS2, CS6 (OK, I’m addicted) MUST BE ABLE TO PROCESS 16-BIT IMAGES Single Shot Star/Constellation Image Non-trailed stars images Mount camera with wide-angle lens on tripod 6D, EF 17-40mm f/4L set at 17mm, ISO 3200, 15 sec Star Trails Intervalometer, 60 1-min exposures, ISO 800, blended in Photoshop Deep-Sky (Stage 1) Wide-angle, long exposure (1-2 mins) - No star trails Requires polar-aligned, motorized star tracker - Several commercially available iOptron SkyTracker system Tracker, polar alignment scope, ball head & tripod 4 AA batteries or 9V DC AC adapter Smartphone app available to show where to put Polaris on alignment scope reticle 7.7 lb capacity - ($450) Very portable Image Stacking Program Windows only Cost = $0.00 (Free) S/N = SQRT(Number of Exposures Stacked) Canon 60Da, EF 17-40mm f/4L set at 17mm, ISO 3200, 30 1-minute exposures Meteor Showers Deep-Sky (Stage 2) Long exposure (1-2 min), medium focal length (100 - 500 mm) - No star trails Requires quality, motor-driven, polar-aligned equatorial mount - not auto-guided Mount should have maximum carrying capacity double the heaviest optical system planned Perfect optics on a garbage mount will give garbage images Vixen GP/DX (on wheels) & Paramount MX (semi-permanent) Good polar alignment will yield sharp star images with 1-2 min exposures without auto-guiding 30 1-minute exposures ISO 3200 DSS Photoshop Supernova Asteroids Comets Comet Johnson C/2015 V2 - May 25, 2017 DeepSkyStacker Nebulosity Nebulosity - Stark Labs Camera control, stack exposures, process images & more Windows & Mac - $95 Deep-Sky (Stage 3) Long exposure (1-2 min), long focal length (500 & higher mm) Requires quality, motor-driven, polar-aligned equatorial mount with auto-guiding Guidescope or off-axis guider and guide camera Guider control software compatible with mount & its control software Must learn how to make all this work together I have not achieved this yet and have no experiences to report Canon EOS DSLRs should work just fine Full Disk Lunar & Solar 800 to 1500 mm FL (depending on full frame or APS-C), very fast shutter speeds Takahashi Sky 90 + TV 2x PM 60Da Celestron C5+ (1250 mm f/10) 20Da (1000 mm f/11.2) ISO 250 1/2000 sec ISO 800 1/1250 sec Partial Solar Eclipse Takahashi Sky 90 + TV 2x PM (1000 mm f/11.2), 60Da ISO 250, 1/2000 sec, 10-min interval, Canon EOS Utility Lunar Eclipse Stellarvue SV115 (800 mm f/7), 60Da ISO unk, 1/2000 to 2 sec, 5-min interval, Canon EOS Utility High-Resolution Lunar, Planetary & Solar “Lucky Imaging” - Jerry Lodriguss Take a ‘bizillion’ images, stack the best few thousand to obtain great final image Video allows capture of thousands of sub-images in just minutes Stacking & powerful Wavelet processing Windows only, Cost $0.00 (Free) Stacking only Windows only, Cost $0.00 (Free) Stack in AutoStakkert, Wavelet process in Registax Canon 60Da in Crop 640 x 480 video mode, 8-bit MOV format video Camera control using EOS Utility First issue: RegiStax & AutoStakkert cannot read MOV format video Must convert MOV video to AVI video Second issue: Several AVI video codices; Windows cannot read all of them Solution: VirtualDub Windows - Cost $0.00 (Free) 5-minute video, 60 fps (18,000 frames), adjust image intensity with ISO Convert MOV to AVI, correct AVI in VirtualDub Open AVI in AutoStakkert, stack 1000-6000 frames, wavelet process in RegiStax Example - Jupiter Celestron C6 SCT, 150 mm dia, 1,500 mm FL, 1.6x ScopeTronix amplifier, Canon 60Da 2,400 mm FL, f/16 equivalent Single frame Stack of 1500 Wavelet Process August 6, 2018 - Celestron EdgeHD 9.25 + 1.6x ScopeTronix amplifier 3759mm FL, f/16 DSLR Shortcomings 1) The imaging chip is not cooled, limiting the maximum exposure length. During exposures, chip warms up and increases thermal noise. I have never seen DSLR image utilizing exposures greater than 5 minutes. Stacking multiple exposures is critical to achieve good signal to noise and image intensity. 2) DSLRs are one-shot-color (OSC) cameras with a Bayer filter covering the chip. Algorithms are used to ‘estimate’ the actual color in each pixel, resulting in a slight reduction in resolution. Light intensity hitting each pixel is about 1/3 that for a monochrome chip, so stacking multiple images required. 3) OSC cameras are not ‘good’ for solar H-α imaging. Bayer filter blocks large amount of light and significantly decrease resolution. Detail on solar disk is ‘muddled’. Monochrome camera would be better choice for solar H-α imaging. 4) Video mode limited to 60 fps as slowest frame rate; can be faster. For dim objects like Saturn, acceptable image intensity can only be achieved be increasing ISO, resulting in noisier sub-frames, so… stacking multiple images required. November 7, 2018 .
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