CPA vs FITS files and processing

Calibration tools, stacking, aligning,..
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rottielover
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Sat May 11, 2019 12:11 pm

I'm not sure where to put this topic so I guessed Processing.

I have a list of related questions:

1) CPA vs FITS format - I saw mention that the CPA format is a lossless compression, I assume there are more advantages over FITS as well, is there a list of things/reasons why CPA would be the better way to go?

2) I have a prior dark library from another software in FITS format, when I tried to use these to calibrate my new CPA light frames I got an error that said something about the pixel size if I recall correctly, I'm guessing that the error message is probably just the wrong translation to english, and should I just assume to use CPA for all the calibration frames as well? (I shot my flats and lights last night in CPA, so I just need to re-shoot my darks and bias in CPA format??)

3) When it comes to processing, I've been a pixinsight user for quite some time and I am most familiar with it for processing. I would like to process my data in both Prism and Pi in order to make some comparisons, is there a recommended point at which I should export my files from Prism as FITS files to get them over to PI (maybe after stacking?)

4) Kind of a dumb question - Can anyone recomend a good format for storing your files in? I have a seperate "data" drive the D drive, I created a folder called Prism under that I have a DarkLib folder with BIAS and DARK folders, and under that I have a seperate folder for each Camera (290mini, 1600mm, Canon70D).
I'm starting to think I would have been better off doing 3 top folders one for each camera and then the DARK and BIAS folders under those. Now here is the real question - when I am processing and use the calibration wizard, it seems like it's looking for a single folder that holds ALL the master files? Should I have a single folder like "calibration frames" that just contains all the master bias, dark and flats for both imaging cameras?

Sorry for the multipart thread, but I figure these are all related to each other.
Hamza Touhami
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Wed May 22, 2019 9:51 am

rottielover wrote:
Sat May 11, 2019 12:11 pm
1) CPA vs FITS format - I saw mention that the CPA format is a lossless compression, I assume there are more advantages over FITS as well, is there a list of things/reasons why CPA would be the better way to go?
Yes there sre of course. The CPA file is about a quarter the size of a regular fit of the same bit depth.
rottielover wrote:
Sat May 11, 2019 12:11 pm
2) I have a prior dark library from another software in FITS format, when I tried to use these to calibrate my new CPA light frames I got an error that said something about the pixel size if I recall correctly, I'm guessing that the error message is probably just the wrong translation to english, and should I just assume to use CPA for all the calibration frames as well? (I shot my flats and lights last night in CPA, so I just need to re-shoot my darks and bias in CPA format??)
Yes, they will be a different size if the bit depth itself is different. Using 32bit lights with `16bit frames will not work.
rottielover wrote:
Sat May 11, 2019 12:11 pm
3) When it comes to processing, I've been a pixinsight user for quite some time and I am most familiar with it for processing. I would like to process my data in both Prism and Pi in order to make some comparisons, is there a recommended point at which I should export my files from Prism as FITS files to get them over to PI (maybe after stacking?)
This is incredibly subjective I am afraid. One example I always give people is that the JANUS team uses PRISM to pre-process and photoshop topost-process and yet they publish some of the best images any amateurs has ever taken. It really all depends on what you want to do. We preach simplicity and PRISM does provide that. I personally do all my acquisition and pre-processing in PRISM then move to PS/APP. It depends on the target also. If there is a lot of data, PRISM suffices.
rottielover wrote:
Sat May 11, 2019 12:11 pm
4) Kind of a dumb question - Can anyone recomend a good format for storing your files in? I have a seperate "data" drive the D drive, I created a folder called Prism under that I have a DarkLib folder with BIAS and DARK folders, and under that I have a seperate folder for each Camera (290mini, 1600mm, Canon70D).
I'm starting to think I would have been better off doing 3 top folders one for each camera and then the DARK and BIAS folders under those. Now here is the real question - when I am processing and use the calibration wizard, it seems like it's looking for a single folder that holds ALL the master files? Should I have a single folder like "calibration frames" that just contains all the master bias, dark and flats for both imaging cameras?
Well, I have a separate top folder for both my setups. I store a folder called Calibrationi in each and then it is broken down by month. I only shoot calibration each month or when I physically alter the scopes e.g: oriontation, collimatons etc..

this is abaility to just pick calibration folders is on the to do list as well
Hamza Touhami | Site Administrator
Hyperion-Astronomy.com
rottielover
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Location: Missouri, USA
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Fri May 24, 2019 8:00 am

Thank you Hamza!

I need to re-watch your processing video's on YouTube a few more times. Would it be possible for the JANUS team's workflow to be posted? (As in the steps they take when processing?)

I think I'm going to start keeping my data in a similar way. Here is what I am thinking: Top level folder AstroRAW, Next level for the Camera/ or Equipment Config or Remote Source (I've got a Chilescope account now). Then the next level will be the target name, and finally a subfolder for the date.

I'm thinking this format because I would like to start taking data on targets on more than one night. I'm finding that it's very hard to get as much data as you want to in just one night on a target ;)
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