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Andromeda


Ben
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Thank you!

This was stacked from about 350 light frames. Each sub was a 30 second exposure taken with an old Tamron Mirror lens 500mm F8 adapted to he A7rII. Tracked with a drift aligned but unguided Sky watcher - Star Adventurer mount. Except for 6 subs all frames were aquired from the inner city of Bonn - Germany, a bortle 8-9 place, that means only constellation Stars can be seen with the bare eye. So I am really happy I got through all this light pollution.

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OK, thats not bad at all. I live near Heilbronn, so I tried a Milky Way shoot ... but that did not work so well, too much light pollution. However using a 200mm lens, no tracking at all, and 100 x 1s subs I could just get M11 (Wild Duck Cluster) and really I had no idea what I was doing.

 

 

And this is possible even with the light pollution of German cities! ... I've already ordered a Scope and tracking mount, the winter here is so grey and depressing, makes more sense to take photos of the heavens.

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Thank you!

This was stacked from about 350 light frames. Each sub was a 30 second exposure taken with an old Tamron Mirror lens 500mm F8 adapted to he A7rII. Tracked with a drift aligned but unguided Sky watcher - Star Adventurer mount. Except for 6 subs all frames were aquired from the inner city of Bonn - Germany, a bortle 8-9 place, that means only constellation Stars can be seen with the bare eye. So I am really happy I got through all this light pollution.

 

That is an incredibly beautiful photo.

 

Did you use Long Exposure Noise reduction when taking your shots or did you take separate dark photos after getting all your light photos? What stacking program did you use? I have used Deep Sky Stacker with some success on a few photos with multi-shot Milky Way photos.

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@timde : Light pollution unfortunately is hard to mitigate, but there are some things that can be done to fix or lessen it. I only shoot after astronomical darkness has set (roughly 1 1/2h after sunset), I avoid shooting when the moon has more than 25% as it's blue cast lessens the contrast equally to the yellowish cast of city-light pollution at night. When working with ultra wide to normal focal lengths, didymium filters can help tremendously. The effect of these filters has diminishing returns as your focal length increases and they take away roughly 1/3 of a stop of light(mostly unwanted light but also some of the significant light). In post processing you need to be aware that the pollution is added light and should not be countered by changing white balance, tint or hue(neither globally nor locally) but rather use color gradients with complimentary colors and after you manage to match the color, increase contrast with the same gradient until the fixed area black point matches the rest of th frame.

 

@chiapeteater : For this image I used deep sky stacker with Sigma-Kappa clipping (Sigma 3, and 5 Iterations). Shots were taken with in camera noise reduction turned off and I took some dark frames, but they did not seem to make a difference in the final result. I have 1 flat frame for each aperture of all my lenses and that seems to be sufficient to counter vignetting artifacts. The problem with deep sky stacker however is that there is no way to correct for distortion. Most of the time this is not a problem when working with long focal lengths but if you are doing widefield shots below 50mm with untracked aquisition photoshop alignment gives better results. Photoshop however struggles with too many layers as it is meant to work on ram rather than hdd/sdd. On mac os with 16GB of Ram I can may be stack 32 42MP layers without Photoshop crashing all of the time.

 

Hope this helps

 

Ben

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