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Old 13-04-2012, 11:07 AM
mbaddah (Mohammed)
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Possible to de-rotate/stack wide-field milkway shot on unguided tripod?

Hi,

I was wondering would it be possible to take a series of wide-field milkyway shots on fixed unguided tripod (f2.8, ~17mm 30seconds) then de-rotate and stack the images using software to create a similar image to a long exposure tracking shot? I want to do something like this to minimise noise and capture more details.

I was thinking if you create multiple layers in photoshop and just mask the foreground (trees, land whatever) this would be possible? Thanks for the help.

Mo.

Last edited by mbaddah; 13-04-2012 at 12:15 PM.
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Old 13-04-2012, 05:07 PM
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gregbradley
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You can create a duplicate layer, assign it to darken mode then use the offset filter to adjust vertical and horizontal shifts and reduce elongated stars. It has a certain workability but it is a fix and never as good as properly tracked images.

Greg.
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Old 13-04-2012, 05:17 PM
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jjjnettie (Jeanette)
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You can download a plugin called "Star Rounder". It helps to a point, but pushed to far, as with most processing, it will start to degrade the image.
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Old 13-04-2012, 05:23 PM
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Narrowfield rules!

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I think mo means rotation between images, not eggy stars. You wouldn't get eggs at 17mm 30secs. Yes, auto align should do that, manual if not. So long as edge distortion doesn't cause a mess at the edges.
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Old 14-04-2012, 01:41 PM
mbaddah (Mohammed)
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Thanks guys for the responses. Looks like properly tracked images are the only way to go unfortunately.
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Old 14-04-2012, 06:03 PM
Mighty_oz (Marcus)
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If u want a challenge have a look at Iris, that does something like that, examples on their web site i think.
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Old 15-04-2012, 11:07 AM
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More stars please!

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Hey Mohammed,

I've taken this approach many times and it's definitely do-able. Stacking in DSS (Deepspace Stacker) is the best way to go, then edit it in Photoshop (Im assuming your proficient with CS and post processing). Stacking in DSS removes any rotation and automatically aligns your images. If you haven't used it before, it does take a little while to figure out whats going on, but its extremely powerful.

I'm not sure what you experience in Photography is like, so do excuse me if I sound up myself but always remember to shoot in RAW, as stacking in RAW in DSS gives you much more flexibility and stretching ability.

Best of luck! Do post your results here
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Old 15-04-2012, 11:12 AM
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More stars please!

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Oh and, take a few dark images too to reduce the noise further. My 6 year old DSLR is shocking! But i've attached two images that Ive taken through my scope to illustrate the point. One is a single raw file, the other is 108 images stacked with 30 dark frames.
Attached Thumbnails
Click for full-size image (DSC_1464.jpg)
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Click for full-size image (Eta Carina 80ED - Edited.jpg)
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