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Calibration Frames/ Cal Libraries

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#1 CrookedEyes

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Posted 12 April 2021 - 02:05 PM

Hi, all!

 

I had a quick question about building calibration libraries and whatnot. Would it even be worth it for someone like me? The reason I ask is that I have to set my scope up every time I image. When I tear it down, I pull the imaging train off as the telescope doesn't sit high enough on the losmandy plate for me to leave it on and store it on my desk in my office space. I leave the imaging train intact and removed it as a whole, removing it from the telescope at the field flattener and including everything back to the camera. I know that orientation plays a role in that, when taking calibration frames, it has to be the same orientation as were taken with lights. Since it is coming off of the telescope each imaging session, would it be advised to take calibration frames for every session? I would prefer to build a calibration library but realized last night as I finished my calibration session, that when I disconnected the imaging train, the collar on my Esprit 100 rotated slightly as I removed the imaging train. How much can an ever so slight rotation affect the quality of the calibration frames if I am unsure if it is in the exact orientation that it was in when taking the cal. images? Is it negligible if it it is ever so slightly out of rotation? It's just something that I was curious about since it rotated on me last night. I plan on putting the telescope up on a stand of sorts so I can keep the imaging train up off the desk while leaving it connected for this reason and others. Would my calibration frames from last night only be good for the imaging session the night before? Thank you for taking a look at my question and I appreciate any responses you all may give! Thank you and clear skies!



#2 jonnybravo0311

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Posted 12 April 2021 - 02:18 PM

Flats are the ones where keeping your imaging train together matters. Take those before tearing down the gear. Looking at your signature, you've got a cooled camera and are using NINA. You can create your dark library at any time. However, because you are setting up and tearing down your gear every session, you need to take your flats every session.


Edited by jonnybravo0311, 12 April 2021 - 02:18 PM.

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#3 CrookedEyes

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Posted 12 April 2021 - 03:04 PM

Flats are the ones where keeping your imaging train together matters. Take those before tearing down the gear. Looking at your signature, you've got a cooled camera and are using NINA. You can create your dark library at any time. However, because you are setting up and tearing down your gear every session, you need to take your flats every session.

Thanks, jonny! It is a relief to know that it's one of the quicker of the calibration frames that I will need to repeat each time! If I were to tear down, but leave the imaging train and telescope intact, would I technically be able to have a flat library then or is that still not recommended unless I have a permanent setup? Thanks again for your quick reply! 


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#4 PirateMike

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Posted 12 April 2021 - 03:13 PM

Even if you have a permanent setup, flats should be taken as soon as possible as you want the dust/dirt in your flat frames to match the dust/dirt in you light frames. If you wait until later you may find that the dust/dirt has moved and your dust/dirt in your lights and flats no longer match.

 

Proper darks and bias frames can be taken anytime.

 

 

Miguel   8-)

 

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#5 terry59

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Posted 12 April 2021 - 03:25 PM

I reuse flats until they stop working which is a long time. I set up each time also and recommend you invest in risers like these 

 

 

https://www.stellarv...dard-riser-set/



#6 bobzeq25

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Posted 12 April 2021 - 03:26 PM

Thanks, jonny! It is a relief to know that it's one of the quicker of the calibration frames that I will need to repeat each time! If I were to tear down, but leave the imaging train and telescope intact, would I technically be able to have a flat library then or is that still not recommended unless I have a permanent setup? Thanks again for your quick reply! 

I've done that.  It's better to take flats every observing session.  Dust moves.  <smile>


Edited by bobzeq25, 12 April 2021 - 03:26 PM.

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#7 CrookedEyes

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Posted 20 April 2021 - 11:06 PM

Thank you all for all of your help! It has clarified everything very well for me. I did, however, really mess up my calibration frames this past weekend. I took two sets of flats as I was experimenting with my new lcd panel for flats. I tried it with a couple pieces of white paper and I tried it without. Unfortunately, as I was calibrating and integrating in PI, I accidentally used both sets. I think it's else caused a bunch of weird gradients in my color channels. I guess I'll see how it turns out once I assign them to their rightful channels.

I also needed up with the flat darks as I didn't realize that my camera had warmed back up and just shot my flat darks. It wasn't until everything was torn down and I actually started transferring files from the astro laptop to my PC that they were the incorrect temps. I guess I'll just have to learn the hard way. I think those terrible flat darks assisted in the excess noise in the final integrated image for each filter. Then again, it's my first time using PI and following some tutorials so I could have messed that up too.

At any rate, I appreciate everybody's time. Everyone here is very helpful and I am certain I'll start taking some beautiful images eventually with the suggestions from all of you. Thanks again and clear skies!


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