MW Panoramas: Optimizing time for foreground images

Started 8 months ago | Discussions thread
EricTheAstroJunkie Contributing Member • Posts: 961
Re: MW Panoramas: Optimizing time for foreground images

nighthiker wrote:

I disagree as the thread starter is using relatively long exposure times (2 min) which can results in many hot pixels (depending on the camera) which are best removed by a dark frame. Of course he can check if his raw-converter can already 'solve' that problem. As the s/n level for the - dark - foreground isn't that critical one exposure for each pano might be enough. As I don't know the temperature conditions for the thread starter he should be the best person to test and evaluate the different ideas.

Doing multi-row panos I know how helpful flatfields can be. The standard vignette of the usual software is still leaving some anomalies behind which will show up during stretching. So - once again - it depends on the conditions at the photo location (light pollution) and how much processing (stretching) is applied.

Hot pixels and cold pixels are easily removed in software like PixInsight, I've also done it in Photoshop. I've done many many many tracked panoramas as you know, from 20mm up to 135mm with a huge variety of cameras and exposure lengths up to 15min. In camera NR with a single dark frame can be detrimental in some cases, not to mention it halves your valuable imaging time. I shoot in a variety of areas, from -20F up to temps in the 90's, thermal noise sucks in the summer, but post processing has come so far in the last few years there are a huge variety of ways to handle it in software rather than sacrificing dark skies time.

As for flat fields, I'm now shooting with my cooled astro cameras for nightscapes and don't have the luxury of lens profiles, post processing software like PTGui EASILY handles frame to frame vignetting issues that are left over from any adjustments made during raw conversion. My most recent pano that I did last week had some very heavy vignetting since I shot the Voigtlander 50mm APO on my 2600mc Pro, the Voigtlanders have some pretty terrible light falloff into the corners even on APS-C sized sensors. The stitched pano had horrible bands without the vignetting correction applied by PTGui (with the vignetting correction there are zero banding issues), the software also will correct slight color balance differences from frame to frame, it works very very well.

If I were doing deep space stuff where I'm stacking dozens or hundreds of frames, sure, I'll do calibration frames. But widefield panoramas it's just not necessary.

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