DSLR Astrophotography - bf-astro.com

1 dslr AstrophotographyThey startwith a Wide-field Astrophotography The AdvantagesIt s Relatively InexpensiveAll you need is a DLSR a tripodYou Don t Need This! dslr astrophotographers use Canon releases the details of the camera s does not create a truly raw imageSome Nikons allow the Mode 3 work allows the development of third party software,designed specifically for simple median blurring filter is always many stars, as they are seen as prohibits precise image Nikon s Mode 3 Simply start the bulb time exposure and terminate it byturning off the For Mode 3 AvailabilityTake a one-minute dark exposure in Mode 1.

2 This is araw image with no noise reduction camera sees this as a low-power warning andimmediately saves the image without running themedian blurring filterIf Mode 3 is available, that exposure will havenoticeably more hot pixels and a one-minute Mode 3 dark Keep It SimpleUse a wide angle lens (18mm is nice)Use the RAW image format, at the highest ISO settingMount the camera on a sturdy tripodSet the lens to its lowest f-stopShoot 20-30 second exposuresTake about five dark exposures (more on this later)Set the focus to before it s you canget an imagelike this!

3 Nikon D40X18mm @ f/4 ISO 1600 Mode 14 30-Sec exposures4 30-Sec darksAfter taking several Milky Way shots itmay be time to get more at night!However, thereward can be great. Wally Pacholka - BarnDoor TrackerBuild cost ~ $200. Justthe ball head cost $ polar alignment scope isused for set up. Holding agreen laser on the pivothinge also works, but lookout for 30-second exposuresusing a stationary tripod2 5-minute exposureswith a Barn Door Tracker2 5-minute exposureswith a Barn Door TrackerTwo one-minute exposures w/ Barn Door TrackerAstroTracThis is the ultimate portablecamera price is $600, but willbe ~ $1000 with tracks for about two hoursand takes about 90 secondsto GuidedCanon EOS 1000D (ISO 400)12mm 5-minute exposuresShown enlarged to 150%,reveals excellent star shapesand color.

4 Bernhard HublAstroTrac Guided - Canon 200mm 7x5 min exposures Richard TaylorUsing a Modified CameraDSLR CCD chips are very sensitive to infrared light. Thisrequires installing an IR filter over the this also filters out the Ha data that is soimportant for emission nebula Remove the filter!If you are skilled, there are several web sites withinstructions to do it Hutch is one source for new modified Canon s,starting at $ including a 12-month are available so the camera can still be used fordaylight Canon Bernhard HublModified Canon Brian MorgantiFixed Tripod Wide-Field ImagesUse a fast 18-25mm lens.

5 Fixed lenses are still betterthan except for maybe Nikon s $1800 14-24mmQuality wide angle lenses start at about $800 and areworth it if you are going to get serious with starscapes, use a high ISO, the widest lens openingand a single 30-60 second star fields, use a bit lower ISO, close the lens onef-stop and take multiple 20-30 second Door and HighQuality Tracker ImagesWith a DIY tracker, use a maximum FL of 50mm. With ahigh quality commercial tracker, use up to 200mm the lens one or two f-stops and use an ISOsetting of 400 or multiple two to five minute exposures, depending onthe quality of your tracking Dark FramesDarks are taken with the lens tightly covered.

6 Thisproduces an image of the camera s noise and hot the time and ISO to match the light the camera at about the same ambienttemperature as the light processing, the dark frame is subtracted from thelight frame. This removes the hot pixels and inherentcamera at least as many darks as lights, the that we have our light and dark frames, wecan process the rest of the presentation shows the using three freeware Sky Stacker (DSS)IRISGIMPS tart DSS and open the picture and dark Register checked the star detection on Stacking the Standard result the Average stacking mode for the Median stacking mode for Automatic is usually no need to keep temp tab will take a bit of settings seem to be working , set the data for the output OK, until you get to this OK to start stacking.

7 For this exampleDSS thrashes around for about two Final Stacked ImageSave the picture as a 16-bit TIFF for loading into Sky Stacker does good job of stacking, butits image processing features are limited anddifficult to the next step we with use IRIS to do a DDPstretch and save the image as 8-bit, for loadinginto IRIS and load the 16-bit TIFF imageand we get this. Now click Auto, in the Threshold we get the image as a BMP for loading into GIMP and load the 8-bit BMP imageGIMP s initial screen with our image Select Curves, to make a contrast adjustment.

8 A curve like this increases the contrast. This looks good for contrast, but it s a bit green. Checking thebackground color shows that the green is about 45% too Color the green to -45 and click OKThis looks pretty good, but still a bit s try a Hue-Saturation , we don t want any green in an astro image. Selectthe Green button, set the saturation to -100 and click the black point adds more pop to the image. Select the left slider to about 8 looks good, click Lenses for web site for dslr Sky PowerPoint is available Astrophotography