First time out

[rpsfam1]

Hi Everyone,

I will be doing some EAA tonight using my asi294mc-p and SharpCap. Do I understand correctly that I need to save my short exposures as RAW files to get the best results from StarTools? I normally do live stacking in sharpcap and it gives me several options for saving my captures and want to be sure I choose the correct one for StarTools.

Thanks in advance

Patrick

[decay]

Hi Patrick,

welcome!

I don't know SharpCap, but you're right about the format of your shots: it's generally recommended for AP to save the single shots in RAW format to get the best quality for stacking. The output of your stacker should be in FITS format if possible. If I understand correctly, SharpCap already does the (live-) stacking? Then the output should be FITS.

If you like have a look at this documentation:
https://www.startools.org/links--tutori ... od-dataset

Good luck and let us know how you go on!

Best regards, Dietmar.

[Mike in Rancho]

Hi Patrick,



Like Dietmar says, I guess it depends on what your question is as to the right guidance. If you mean you want to post-process the live stack results from SC, then yes save as the deepest quality (at least 16 but hopefully 32 bit) FITS you can, though TIFF might be possible also. Some TIFFs may not open in ST, so you'd have to do a quick test maybe.

However SC may allow, save the linear stack, with no stretching/STF applied, no white balancing or color correction, and so on.

If you are looking to save out individual subs, then yes a RAW and undebayered format is preferred, which may in fact be FITS, preferably 16-bit. You would then use a pre-processing stacker (there are many options) to calibrate those subs with darks, flats, and dark flats and stack them. Follow the ST stacking guidance from the link Dietmar provided depending on the stacker utilized.

[admin]

Further to the excellent advice here, one of the reasons why you would want to avoid live stacking (if you can), is that the live stacker can only use stats from whatever has been coming in.

A post-acquisition stacker can gather stats on all frames that have come in, in its entirety, and make decisions based on that whole. Those decisions will always be better / more informed / accurate. Therefore the stacked dataset will almost always be of better quality, and therefore you will be able to get more detail out of said stack.

Hope that helps!

[rpsfam1]

Thanks to all for the help and advice! Looking at my sharpcap capture folder, it looks like SC saves my images in 4 ways:

1. the individual frames are saved as .png
2. a 16 bit RAW Stack FITS
3: a 32 bit raw stack FITS
4. and "save as viewed which includes all the histogram adjustments I made - those seem to be .png files as well.

If I understand the advice here, the best data for star tools to process is RAW and unstacked? so if Im doing EAA I should do one set of images for real time viewing (live stacked) and then another set for Startool processing (raw and unstacked). IS that right?

Thanks again for the help

Patrick

[decay]

Hi Patrick,

If I understand the advice here, the best data for star tools to process is RAW and unstacked?

No, you need a stack as input for processing with StarTools. So you could use (2) or better (3) but this would imply the downsides of live stacking which Ivo pointed out in his post.

Best would be to find out a way to save the individual frames (1) not as .png, but in RAW format. Then you could stack them afterwards using a standalone stacker of your choice, e.g. DSS ore ASTAP or SIRIL.

As a first step I would suggest to give (3) a try as you probably already have such a stack. For next nights out you could try to find a way to save the individual frames in RAW format, as described above.

Regarding the processing in StarTools please have a look at this
https://www.startools.org/modules/intro ... uick-start

You will find some other (video-) tutorials and other helpful information on this page:
https://www.startools.org/links--tutorials

Best regards, Dietmar.