Beginners Workflow for Live Stacking plus focus and target Tips

Somewhere to share your expertise in using SharpCap
AussieHowie
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Beginners Workflow for Live Stacking plus focus and target Tips

Post by AussieHowie » Thu Feb 13, 2020 1:22 am

Just like normal photography, the key to good images for EAA or AP is to adjust the exposure time and gain to achieve a good "signal" in the histogram. When you have that good key "signal" displayed in the histogram, it means you have neither under nor over-exposed the image and can begin stacking - assured that you have the best possible data in the images.

But beginners to EAA or AP often struggle getting any image at all, or at best some image no-where near as good as they expected. And if they ask forums for what settings they use on different targets, they will get all manner of different settings. The reason is that others use the same camera on different mounts and telescopes so have adjusted the camera(s) to suit their equipment.

This video therefore goes through how a beginner should use the two simple settings of Exposure time and Gain in conjunction with the Display Histogram to get the "good" signal which allows a good exposure to stack. Furthermore, I suggest how you should focus the camera, as well as what targets a beginner should concentrate on ... for at least 3 months! Why? Because the "good" signal in the Display Histogram can be created by many combinations of gain and exposure! So in the video I show how you can easily find those settings and adjust the times to suit your "taste". Be it long exposures at low noise (gain) settings for AP and Eq mounts, all the way down to extremely short exposures at high noise (gain) settings for EAA.

NOTE - While I use the Sharpcap Camera Folder option I am NOT saying you MUST use that too. You will use the Camera Control menu to set Exposure and Gain with your camera connected! I have just used Camera Folder to demonstrate with real raw frames from a night out recently. As where I live a Hurricane (well Cyclone in my country) is just offshore and we have had weeks of rain and flooding and wind. So bored and nothing to do, I made the video to help you all out :) . Cheers
https://youtu.be/0Fvm_DjOgaY

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turfpit
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Re: Beginners Workflow for Live Stacking plus focus and target Tips

Post by turfpit » Thu Feb 13, 2020 7:36 am

Carl

Thanks for doing this, people will be able to find the information more easily. I expect the thread will be lively over time.

Dave

AussieHowie
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Re: Beginners Workflow for Live Stacking plus focus and target Tips

Post by AussieHowie » Thu Feb 13, 2020 12:29 pm

Thanks for telling me about the Tips and Tricks forum Dave ... much better place to have it than hidden in a thread on the main forum.

Cheers.

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Rocket_Guy
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Re: Beginners Workflow for Live Stacking plus focus and target Tips

Post by Rocket_Guy » Thu Feb 13, 2020 9:37 pm

This is a very good video and give quite a lot of good information. I am curious, however, how your somewhat trial and error approach to setting appropriate values for gain and exposure compares to using the Sharpcap "Brain" function. Thanks

AussieHowie
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Re: Beginners Workflow for Live Stacking plus focus and target Tips

Post by AussieHowie » Fri Feb 14, 2020 1:31 am

Thanks for your question. I did not put anything about the brain and other features as I've seen beginners dive in right from the start spending many hours getting platesolving, remote control and reading up on the brain etc and while some get it ... many do not. If you want to dive in and get all the special stuff working ... fine. But if you want a step by small step of basic stuff then the video show how to do it. Even if they end up using the brain they will know how to get it right without using it - which bodes well for the future when (if) they use other software or get into AP or whatever.


Cheers

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Rocket_Guy
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Re: Beginners Workflow for Live Stacking plus focus and target Tips

Post by Rocket_Guy » Fri Feb 14, 2020 3:16 am

Thanks for the response. The main purpose of my question was to try to figure out how you determine the optimum value of exposure vs gain. From my understanding, you basically increase the exposure time and back off on gain bit by bit so as to progressively decrease the noise. Eventually, you must reach a point of diminishing returns with regard to noise reduction (e.g. noise becomes so low that further increases in exposure time don't really help anymore). All you are doing at this point is increasing the exposure time and making the stacking time longer without getting much increase in picture quality. The "Brain" it seems takes care of this by giving you the best picture in the minimum time based on a mathematical algorithm which Robin has detailed elsewhere. What I would like to know is when you are using your trial and error approach, how do you decide when to stop increasing the exposure time (and reducing gain) so as to get the best picture in a given total observation time. Is it just by experience or do you have a more formal method? Thanks again for your great video.

Bill

AussieHowie
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Re: Beginners Workflow for Live Stacking plus focus and target Tips

Post by AussieHowie » Fri Feb 14, 2020 11:39 am

Nope ... I said in the video start with max gain and reduce exposure a tad so you get the histogram 'signal' and start stacking. Get as good an image as you can. Then I said double exposure and tweak down gain until you get the signal again and stack again at that setting. Get as good an image as you can. And compare how easy it was and how good the outcome for each setting. So you get to experience adjusting the stacking histogram for various noise/exposure times. I said in the video you will find a point where you get the best results for your camera on your mount and your OTA, or reach the limit of your patience in waiting for a shot!

Least that was my intent and if you missed that then I've most likely waffled waaaaay to long in the video and lost folks attention. Apologies.

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Rocket_Guy
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Re: Beginners Workflow for Live Stacking plus focus and target Tips

Post by Rocket_Guy » Fri Feb 14, 2020 1:36 pm

No, the video was great and not too long at all. You were quite clear in your video about how to adjust exposure/gain until things looked the best to you. I guess the object of astrophotography is to get something which is pleasing to you and not necessarily precise according to some mathematical criteria. Sometimes I lose sight of that. In any case, thank you again for the video. Looking forward to trying out your suggestions.

Best, Bill

m32guy
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Re: Beginners Workflow for Live Stacking plus focus and target Tips

Post by m32guy » Sun Mar 29, 2020 5:48 pm

I've been at AP for about a year and love this tutorial. Your explanation of the histogram and how the white, black, and midtone levels work in particular was fantastic. The way you demonstrated the impact of each on a real image was really helpful.

Thanks for sharing.

VPR
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Re: Beginners Workflow for Live Stacking plus focus and target Tips

Post by VPR » Sat May 09, 2020 4:17 pm

A very helpful video. I have been using the ‘Brain’ all this time. However, I think there is some very useful info here. You have also presented it in a very concise fashion.

Thanks,
V.P

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