Processing star trails

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22 Nov 2012 - 2:54 PM

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digicammad (e2 Member)

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22 Nov 2012 - 2:56 PM

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What quality did you set the jpeg at? The fragmentation will be as a result of compression so the normal way to avoid it would be to set a high quality.

Metalhead

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22 Nov 2012 - 3:16 PM

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It's not necessarily the quality of the Jpegs, it might be a problem at the "taking" stage.

Am I right in thinking you're stacking several shots to get a long exposure and show movement in the star trails? There might be a chance that you had a long exposure noise correction setting on your camera which takes an equally long shot with the shutter closed to get a "dark frame" which is subtracted from the image just taken. During that time the stars will have moved in the sky by a small amount so when the second shot is taken there's been a time gap.

When you come to stack these images it will leave dark spaces or dots between each trail.

Bit difficult to explain, but it does make sense if you think about it! Or it could simply be the lag of the camera saving the first shot to card before starting the next shot. All depends on lots of factors such as if you used a continuous shooting mode etc, long exposure noise correction on or off, and a number of other things.

Can you provide any more details? Either of the desired end result or the shooting situation?

Sooty_1 (Critique Team)

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24 Nov 2012 - 5:42 PM

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Try processing it full sized, then saving as a jpg full sized, then saving at lower quality. Consider also reducing the size and resolution of the image before the quality.

Nick