9/14/2015Cal Estrada1 Introduction to DSLR Astrophotography Relatively simple and inexpensive. –No guiding required. Using consumer Canon DSLR’s. –Home use camera: Canon t3i, 18 MP No field laptop required. ISO up to 6400, 30 sec or bulb exposures, swivel screen, zoom live focussing Sensitivity diminishes in the red “Ha” emission wavelength. –Fast Reflector vs APO Larger aperature, faster f/#, no chromatic aberration, dewing takes longer, affordable. –Stack of multiple shorter exposures vs single long exposure No guiding required (no AG mount, separate guide scope & camera, or laptop) Freeware “Deep Sky Stacker”, process images on a cloudy or rainy night –Polar Aligned Equatorial Mount Decent unguided second exposures at 800 mm using Celestron CGEM –“Local” Dark Sky sites Blackbird SP, Tuckahoe SP, Cherry Springs SP, Cape Hatteras NC

9/14/2015Cal Estrada2 Celestron CGEM mount with Go-To and Autoguider $1500 new Astro-Tech $ 450 8” f/4, 800mm fl To Polaris Polar alignment scope with offset Imaging Setup, 8” f/4 on Celestron CGEM Hand Controller with 40,000 object Go To Data Base.

9/14/2015Cal Estrada3 Camera Setup and LPR Filter Transmission T Adapter 2” Baader MPCC 2” Hutech LPR Filter Programmable shutter timer. Bulb Mode. N x 90 secs UV and IR Blocking with notch filtering of Orange Street lights and transmission of Ha light Swiveling Live Focus Screen

4/23/12Cal Estrada4 Step by Step Procedures: Setting Up Scope Laser collimate Telescope at Temperature Level Telescope Tripod. Balance DEC and RA Axis with camera attached (counterweights and dovetail) Polar Align and center 2 or 3 alignment stars. No drift alignment needed On Primary Center Mark “Centered” on secondary Returns to laser aperature

9/14/2015Cal Estrada5 Imaging Procedures Camera Setup –Manual Mode, 90 sec exp, ISO, RAW Mode for stacking. –Focus on bright star or Jupiter using “Live Zoom” feature –If not “go to” equipped, find what object you’re looking for Star Maps and TelRad or finder scope. Start with easier, brighter objects. –Take lots and lots of “light” frames, many will be unacceptable for stacking 1 x 75 ISO Note lots of noise in raw images

9/14/2015Cal Estrada6 Screenshots from Deep Sky Stacker. M3 Cluster 8 x ISO Light Frames Only. No flats or darks. Best images without trails or periodic error. Stacked Image, no post processing

9/14/2015Cal Estrada7 Single 75 sec light frame 9 x 75 sec light frame ISO 1600 using modified DSLR PS adjust levels, contrast, sharpen, vibrance Using Deep Sky Stacker

9/14/2015Cal Estrada8 Objects imaged with light frames only (no flats, darks, or bias frames) Unguided 1600 ISO. Levels adjusted and sharpened using Photoshop.

9/14/2015Cal Estrada9 Miscellaneous and other details Maximize “SNR” or Signal to Noise Ratio –Signal: Photons you want to keep Good focused images long exposure images –Noise: Artifacts you don’t want –Light pollution (orange street lights). Use LPR filter –High ISO noise (most common) Take lots of light frames and stack –Dark Signal (removed by dark frames) –Vignetting, dust or smudges (removed by flat frames) –Dew. Newtonians better than SCT’s Optional Accessories: Many available at AstroMart ( –Coma corrector for fast Newtonians –LPR Filters (especially in light polluted “orange” skies) Next Talk: More Advanced Astrophotography Techniques: Autoguiding, Flats Fields, Dark Frames and Dithering