What OSX programs are available for stacking images? I searched all over the forum, but couldn't find anything! Preferably free, if possible.
I wouldn't even bother stacking, just leave the shutter open. Here's one I took recently, 70 minutes straight off the camera:
leave it open and turn your sensor into an oven only to get hot pixel everywhere =/ I use Adobe Photoshop CS3 and that has stacking option.
If all you want is a star trail then a long exposure would be easiest. If you are looking for movement from satellites or comets/asteroids/meteors/whatever then try here.. Helicon Focus - extended depth of field, focus stacking, 3D visualization At least I think you can find out what moved using this program. It works well bringing images together for focus. I suppose you could do it the old fashion way by having two or more Very in focus images and comparing them manually. There is a free program that works with windows if you want to run an emulator, here CombineZM Software Informer: Latest version download, news and info about this Alan Hadley program. CZM betters photos by merging their focused section and creating a new image. These are neat little programs, have fun! BTW Restomage, you might want to map your hot pixels .
its easy in photoshop if you take your images then everything is almost of equal brightness (with exception to stars) then open 1 image in photoshop, add each image into that documant and set them all to lighten.
Never used it myself but Lynkeos may be suitable: Lynkeos home page I did use Keith's image stacker in it's early versions but have since switched to a windows only program Deep Sky Image Stacker. Keith's Stacker can be downloaded here: Keith's Image Stacker 5.0 software download - Mac OS X - VersionTracker That works nicely on the D700, but on some cameras and exposure like that may permanently damage the sensor. That said stacking will ultimately always provide the best solution due to averaging of the random noise. Furthermore there's other options such as stacking that only selects the brightest pixels for the final image which can create very very long startrails without problems caused by light pollution ruining the image (not a fan of your light blue sky).
Unfortunately, you just can't do a solid long exposure with digital like you could on film. Signal to noise ratio just goes through the roof after about 5 mins, and as you can see, it enhances hot pixels and introduces artifacting. DeepSkyStacker Download Made specifically for stacking both deep sky objects and star trails. Just remember to select "average" for the stacking method option. It will detect and remove hot pixels, auto line up your backgrounds and account for each, individual star it detects per image. Telescope Reviews: Viewing list of forums Scroll down to the Astrophotography and Sketching section and have a look through the DSLR and CCD Imaging Threads. This is the program 95% of these guys use.
