Live Stacking Questions

[bluesilver]

Hi, I have been using SharpCap for a little while now, Mainly first of all it was for the live polar alignment which i have to say works extremely well.
Just recently i have only just started to use the smart histogram to get some good numbers for how long an exposure i should be using.

A basic run down of my equipment is:
asi2600mc camera, Scope is Sywatcher Esprit 150m Mount is Ioptron CEM120

So the Live stacking question:
I have watched a few youtube videos of people doing this.
Do you end up getting a better result, same result or slightly worst result by doing live stacking compared to my current method which is probably the old way, taking lights, Flats, Bias and then stacking them in another program, them processing them in another program.?

I am not having much success with my old way and was looking at giving this Live Stacking thing ago.

It appears to look extremely simple and easy once you are all lined up and focused.

I have another question on flats and bias, but will start another post for that to eliminate any confusion.

But any advise on the above question would be greatly appreciated.
Thanks.

[calan]

Honestly, I rarely bother with saving individual frames and then stacking them in something else anymore.

When it's properly set up and filtered, SC's stacking just works. The only exception would normally be if I need lots of time on a target over multiple nights. And even then, I can use SC's folder camera option to try different types of stacking or filtering, or easily create a new stack as more subs are added...assuming they are all captured with the same setup.

Yes, I can get a more precise stack by using PI or DSS if needed (simply because they offer so many specific stacking options)... but it's not worth the hassle, disk space, and time for me, based on the minimal gains I see in the end after processing.

I have several camera profiles set up (various gains and exposure lengths), and a library of master darks made with SC for each profile. At the beginning of each session, I get the camera positioned and focused, capture a master flat, do a quick polar alignment, and then get on target and start stacking. I save the 16 bit FITS at 30 minute intervals or whatever for processing in PI, and a quick png save just for reference.

Simple, and more than adequate for creating images for my personal enjoyment.

[admin]

Hi,

If you set up like-for-like tests, ie the same images captured in SharpCap and the same choices for whether or not to use dark/flat/dark flat, then I expect that you could get better results in PixInsight or DSS than the live stacking in SharpCap manages. On the other hand, if you can get an image with live stacking and get stuck when working with PI or DSS then the SharpCap images are better by default

Basically, as Calan says, it's all down to whether you want to put in the extra work to re-run the stacking afterwards in another application - the option is there if you save the raw frames, but do you have the time/inclination?

cheers,

Robin

[calan]

The one real drawback to not saving individual frames (whether you stack them later or not), is that if SC crashes or something stupid happens, you've just lost whatever time you had on target.

As an example of "something stupid happens", last night I was on a target and it was looking really good. I had saved the stack off at 30 minutes, but then forgot to after that. I paused the stacking to nudge the scope for a manual dither at around 2 hours, and when I went to resume it, I accidently hit the clear button. 2 hours of good data down the drain.

And that brings up two feature requests @Robin.

1). Add an optional confirmation to the "Clear" button
2). See my other request for automatically saving the stack without resetting it.

[bluesilver]

Very much appreciated, great advice and explained simple enough for me to get my head around.
So save files as 16 bit FIT files?
This may be a question that was already explained, so sorry if i am going back over this,

But is there an option to do both, that is do the live stacking that i am talking about and also save each individual image?
So say i end up with 240, 37 second exposures, One file with have them all stacked as a final image / product, then another file will have all 240 images?

Just incase i want to for some reason stack the 240 images in another program like DSS for instance.

Or is it best to just have one or the other?
I am going to re watch a few of the live stacking videos to see if i can pick up on some things that i am asking about also.
But have to say, it is a great program and the pro version definitely makes things that much easier.
Very much appreciated.
Thanks.

[calan]

In the "Live Stacking" section, there is a box called "Raw Frames". You can use that to save the raw frames, with various options. You can save every frame (Save all), or only the ones that pass the current FWHM and brightness stacking filters (Save stacked), for example.

If that is set to "Save none", then nothing will be saved unless you specifically save the stack with the box under "Actions" > "Save".

[bluesilver]

Appreciate that advice,
Will also go back in to the manual and have another read on those.
I do plan to run the FWHM and brightness stacking filters, so will be possibly looking at saving both the stacked and unstacked images with the FWHM and brightness stacking filters applies if possible.
Vey much appreciated.

[bluesilver]

Hi again, So i have just been watching more video yet again and doing a bit more research.
So for me, my goal is in line with producing great images for print.
So live stacking may not possibly be what i want, but I think if i am correct, what i need is, to be able to save each individual frame and latter process it, i don't mid taking the time processing.
But i still think that taking heaps of short exposures ( like 37 seconds ) and then stacking them will be better than say taking less long 5 minute exposures.

So, going forward and apologies if i am getting off track here by mentioning another stacking software,
But will it still work if i make the Dark frame, make the Flat frame and bias frame (I think the bias frame is created when you create the flat frame ? )
Run the live stack to get say 250 frames,
Save it as individual frames.

Then running another stacking program like DSS?

Once again, apologies is i am getting off track here.

[turfpit]

i still think that taking heaps of short exposures ( like 37 seconds ) and then stacking them will be better than say taking less long 5 minute exposures.

The only way to be sure is to carry out both captures and compare the outcomes. A lot will depend on your sky conditions - for a high Bortle figure the shorter exposures may give a better outcome. Also, the tracking capability of your mount and guiding setup will impact the quality of the result. Post processing skills will also be a factor to consider. There are no definitive answers to this because of the wide variations in sky conditions and equipment combinations. At best, the answers you get in the forum can only be considered as guidelines.

Dave

[calan]

Hi again, So i have just been watching more video yet again and doing a bit more research.
So for me, my goal is in line with producing great images for print.
So live stacking may not possibly be what i want, but I think if i am correct, what i need is, to be able to save each individual frame and latter process it, i don't mid taking the time processing.
But i still think that taking heaps of short exposures ( like 37 seconds ) and then stacking them will be better than say taking less long 5 minute exposures.

So, going forward and apologies if i am getting off track here by mentioning another stacking software,
But will it still work if i make the Dark frame, make the Flat frame and bias frame (I think the bias frame is created when you create the flat frame ? )
Run the live stack to get say 250 frames,
Save it as individual frames.

Then running another stacking program like DSS?

Once again, apologies is i am getting off track here.

You can save individual darks, bias, and flats... and then stack them externally to create master calibration files, just like you can light frames. Or, you can let Sharpcap create the masters, and then stack them externally with all your saved light frames. Or, you can let Sharpcap do all the stacking to give you one final FITS file. It is extremely flexible and allows you to create images any way you want.

Using the FWHM and brightness filters is a great way to avoid frames that you won't want to stack externally. On the occasions that I do save raw frames for later stacking, I usually save only the filtered ones. One exception to this is if I plan on running them back through Sharpcap at a later time using the folder camera. In that case, I may save all of them, and then use the filters on the folder camera pass, trying different values of FWHM to see how it affects the stacking.

As for your ideal exposure and gain settings... what Dave said ^. Use the brain icon in the histogram tool. It will measure your sky conditions and make recommendations based on your sensor analysis.

FWIW - 37 seconds would be a long exposure for me. I typically get best results when stacking 10 or even 5 second subs at 125 or 150 gain. (ASI294MC-Pro)

I don't have the link handy, but there is a Youtube video floating around of a presentation that Robin gave about camera noise and the effects of gain and exposure on it. It is fantastic, and IMHO, should be required watching for anyone doing astrophotography. Hopefully someone has it; if not I'll see if I can find it.

EDIT:

After reading your posts again, you may be missing this point, but... you can save the raw files while still letting SC do the stacking. Then if the final stacked image is to your liking, you are done. If not, you can always open up your other stacking program of choice and stack the raw frames you saved in it, and compare the results.