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So I am a new comer to the world of astrophotography and I'm having some difficulty trying to get images to stack they way I'm wanting them to stack. Obviously I can't blame to problem on the program so I'm wondering what I'm doing wrong. I've tried find different guides online but to no success. So I'm not trying any fancy shots mainly because I only have my Canon DSLR with a 35-70mm lens and a telescopic 100-300mm lens and a tripod and no way of tracking at the moment.

From other topics I found out that taking pictures that did not have a tracking device do not have an effect on stacking images so I went out with my telescopic lens to try and capture the Andromeda Galaxy. Went out and took 35 5sec exposures at 300mm. I got a little bit of star trailing but that was fine because my goal was to figure out DSS and stacking not fine tune picture taking. So I load the picture in DSS, I computed the number of stars to 20%(37 starts found), set to Mosaic Mode, Median Light, Automatic alignment and clicked OK to start stacking. The end result is the same I've gotten over and over and cant figure out what I'm doing wrong. The result I keep getting is making the image look like I am trying to purposely get star trails instead of a clearer crisper detailed image. What I am not doing right?

Thanks for the help.

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I imagine DSS is actually, taking the best single frame and outputting that. A small amount of star trailling is acceptable to DSS, but it has to be small. I'd imagine that with 5 second exposures you have more than small trailing, and therefore DSS can't combine the images. If you post a sub, we can check that.

There's a rule of thumb that seems to work, 600/FL = non trailed exposure time.

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The individual subs are out of focus, but I still think that DSS should stack them.

Have you tried going through each sub and manually picking the alignment star.

It's [DSS] not happy about something, difficult to tell really from one sub.

Failing that, zip them together and email then to me (email in sig) and I'll have a play.

Cheers

Ant

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I have my lens focus set to infinity so I guess I'll have to try and just focus manually next time. And I don't know how to manually pick stars to align them in DSS. I tried looking but couldn't find anything. Ill email you the rest of my subs when I get home.

Btw if the first one was out of focus all the others will be to. FYI.

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DSS may be fooled into thinking that the "smudge" of M31 is a comet - if you have set DSS (or the defaults are set) to stack a comet but trail stars then it will produce an image like yours. Probably no help in this case but just an idea!

Edited by Bizibilder
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With regard to the focusing, I find a Bahtinov mask pretty essential together with APT which can control the camera lens and and the focus without having to touch the camera. At around £11 a worthwhile investment. Setting the focus on infinity just doesn't work for astro.

Dave

Edited by Dave Smith
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Thanks for all the help everyone. Will try what everyone suggested and see what I come up with. Special thanks to ant for the extra help.

Dave- Wheres a good place to get a Bahtinov mask that would fit my DSLR lens? All I'm finding are the masks for Telescope lenses.

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