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Processing star trails

22 Nov 2012 2:54PM
I have just processed a photo in Raw Elements 9. On converting it to jpeg , the trails have fragmented. Any ideas how I can remedy this?

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digicammad Plus
14 22.0k 39 United Kingdom
22 Nov 2012 2:56PM
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.
22 Nov 2012 3:09PM
Thanks digicammad. I will give up the quality now and see if that works. Great
Metalhead Plus
10 1.9k 2 England
22 Nov 2012 3:16PM
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?
24 Nov 2012 2:27PM
Thanks for your info. I actually just put the camera on bulb and left it for 45mins. There was almost no moon so the sky was dark. I had the noise reduction on, ISO 100 and F4.5 I will give it another go when the sky is suitable again. I have done stacking but I will read up about it.
I had the quality set at 2 tried upping it but it didnt make any difference. I have since managed to convert to jpeg but the photo is still 6+MB and I had hoped to get it below 1Mb
Sooty_1 Plus
7 1.5k 221 United Kingdom
24 Nov 2012 5:42PM
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.

24 Nov 2012 5:49PM
Thanks I will give that a go

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