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Flats and master flat calibration doesnt work with my files  

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(@simon)
Molecular Cloud Customer
Joined: 6 months ago
Posts: 5
March 27, 2020 01:03  

Hello.

I have a problem when taking flats trough my asi air so i decided to take them manual trough my dslr.

Now my problem is that my flats don't get accepted probably because they are 2 different files.

The files on my air are fit files and the flats that come out my dslr are cr2 files.

Is it because i am working with 2 different files? I get a critical warning when the flats are being calibrated flats are always on the same iso and settings like my lights (the only thing different is my exposure time). 

I am using a asi air as controlling unit and it doesn't seem possible to get good flats true my asi air.

I tried different exposure times for the flats but i can only get a good histogram true av mode on my dslr. Problem with the air is that its only working when setting the air to bulb mode? the moment you try to switch to av mode asi air stops working with a dslr. 

Anyone thats get a critical error when calibrating flats made trough av mode? And how am i supposed to make decent flats trough asi air I use a canon eos 60d.

Thank you in advance hopefully someone can tell me how to make acceptable flats with the air.

Regards Simon


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(@vincent-mod)
Quasar Admin
Joined: 3 years ago
Posts: 1746
March 27, 2020 11:09  

What does the error say exactly? I think it might be because the ASIAir is changing the files just a bit when converting. Maybe the dimensions changed slightly? If that's the case they will not be compatible.


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(@simon)
Molecular Cloud Customer
Joined: 6 months ago
Posts: 5
March 28, 2020 02:50  

@vincent-mod

Hello.

The error says that my flats have to be the same iso as the lights but i never change my iso. 

what do you mean with the dimensions changed slightly, that i get in different focus?

I never change focus after taking lights, what i do at first is putting off my tracking on the air and then i loosen the cludges so i can flip the scope to the zenith to take the flats.

i tried with a led panel and a white t shirt and also with a t-shirt and turning it to a light source. 

when i load the flats and they are being streched they have horizontal lines. If i shoot the flats with the av mode without the asi air they look light blue and then the histogram seems ok. but when mixin fit files from the air with my flats i have this error. 

To be honest i never tried the flats out of the air because they are showing these lines. Should i try to stack with these weird lines in my flats? When i put it to 0 procent strech the flats from the asi air just look white. 

I am probbably doing this completely wrong and today i wil wait until dawn for taking flats with a t shirt and the blue sky. 

Also i don't see dust bunny's on my flats and probably they are suposed to have these bunny's and dirt? 

Please forgive my for my stupid questions and actions 

regards

 


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(@wvreeven)
Neutron Star Customer
Joined: 2 years ago
Posts: 177
March 28, 2020 03:10  

Is it possible to configure the ASIAir such that the images are saved as CR2 as well? Probably look for a setting concerning native or raw. When the camera takes an image it produces CR2 data which the air converts to fits and that probably involves a loss of a tiny bit of the data because the image formats are not the same. It is always best to make sure that you get the file format that is supported natively by your camera to avoid problems with processing them.

 

HTH, Wouter


(@vincent-mod)
Quasar Admin
Joined: 3 years ago
Posts: 1746
March 28, 2020 08:46  
Posted by: @simon

Also i don't see dust bunny's on my flats and probably they are suposed to have these bunny's and dirt? 

Please forgive my for my stupid questions and actions 

No worries Simon, we're here to help. 😉

Like Wouter mentions, have a good look in the manual for the ASI-Air to see if you can change this setting. It should just store the raw files and not convert them, if possible. Fits should work, but it might be that the Air doesn't store proper Fits information in it for instance or it changes something else. Mixing the different formats may then cause issues, so it's best to always stick with the direct raw files the camera produces.

I think it's also a good idea for you to take a step back and study how to make proper flats. Flats are notoriously difficult for many to take properly. Most important things when taking them are;

1. The focus needs to be exactly the same as the focus you had while taking light frames.
2. You need to aim for exposures that are about a second per flat (give or take) and get to 50% of the linear histogram of the camera sensor. If you judge the flats by looking on the back of your DSLR, this will be a bit difficult as that's not a linear histogram. Try to aim for a peak at about 2/3 of that histogram if you can't judge it on a computer.
3. I'd advice a flat panel, personally I like that a lot as it's always the same, evenly illuminated and can be controlled in the amount of light. Not necessary, but I think it's easier than using the shirt method.


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(@simon)
Molecular Cloud Customer
Joined: 6 months ago
Posts: 5
March 30, 2020 01:22  

Hello

I am trying to stack a picture right now and this time the flats came right out of the asi air. I used a white t-shirt and the morning sky and took flats of 1sec,2sec.3sec and 5sec.

I was plannig to use the 2sec version because in these flats i can clearly see dust bunny's and gradient.  but when i load them they turn red so i suppose they wont work again.  So its not about the different files i guess. 

My focus and iso remained the same it was right after the imaging session. 

Wil app trow out bad flats or what seems to be the problem here? @vincent it is tricky i know and i wil do anything i can to make good flats, I read about the histogram and i am aware this schould be at 50 procent of the histogram. (i can read a histogram on a dslr but with my asi the histogram is completely different)

So i shot a session of 1.2.3. and 5 seconds. i could trie a flat panel but i am running low on astro budget and i work with a 8inch so i think the panel schould be huge. Why are my flats turning red in the loading bar at the bottom of the screen? 

Again sorry for my poor English and thank you very much for the help love the dedication of this company!

regards

 


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(@vincent-mod)
Quasar Admin
Joined: 3 years ago
Posts: 1746
March 30, 2020 09:44  

No problem Simon and thank you. 🙂

So, since you were taking flats with very different exposures, it kind of tells me you didn't know what to look for on the histogram, is that a correct assumption? If the histogram on the Air is different, maybe it does show a linear one. In either case, just look at either the histogram on the Air or on your DSLR, stick to one and try to get the peak around the middle to 2/3 of it. From there we can have a better look again, try to do this step-by-step.

If you have such a flat I'll ask you to upload it here so we can have a closer look. Does that sound ok?


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(@simon)
Molecular Cloud Customer
Joined: 6 months ago
Posts: 5
March 31, 2020 04:26  

@vincent-mod

Yes you are correct i can't read the histogram of the asi air. A friend just told me to store my files on the sd card from the dslr a bit like you are saying so i can take a look on the histogram on the screen of my dslr (on the dslr it's much more easy to read then on the asi air). Is there a way for me to check my histogram on my pc (without software like photoshop) because i am on a budget.

I have had succes with loading the flats today and they removed vignetting but now i have these weird lines (something like gradient or i don't know what to cal it)in my picture (probably because the flats ar not good). 

I changed the flat file i loaded in to fit files in the 1) load step of app and they got in. also i think i was doing it wrong with the (multi channel and multi session) step. I was switching in between the lps session and other sessions why i don't know i think i thougt every step was a "session". 

So if i only use one filter in one imaging session do i have to work with multi session? Sometimes i do have different imaging nights but most of the time its just 30 times 300s. 

I know i am a slow learner and i think it's just because i don't know how to work with app in a correct way yet. I found a tutorial of astro addict and to be honest i just copy what he does. The first time i tried app i was doing it with a video of Sara wager and know i do it like the tuturial from astro addict. Also looked up some video's from Mabula (a dslr workflow) but i realy don't know what video i should follow. 

For people like me it would be very helpfull if there was something like astro pixel processor for dummies. I am realy sorry that you have to try to understand what i am saying here i know my writing and reading is terrible. 

If i am able to i wil leave 2 photos here of leo's triplet each 25 times 300s exposure the 1st one with flats in it the last one without flats in them. each taken wit 15 dark frames 300s and 21 bias frames shortest exposure posible captured the same night with the same focus. 

I wil keep on trying to make good flats and thank you for al the help! 

regards


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(@simon)
Molecular Cloud Customer
Joined: 6 months ago
Posts: 5
March 31, 2020 04:28  

@vincent-mod

leo zonder flat
St avg 7200.0s AR LN 7.0 3.25 8 x 1.0 LZ3 NS full qua mult sc BWMV nor AAD RE MBB5 LPS session 1 1stLNC it1 St

 

So here you can see i have seriuos issues. the left one is without flats the right one with. 

This post was modified 2 months ago by Simon Baert

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(@vincent-mod)
Quasar Admin
Joined: 3 years ago
Posts: 1746
April 4, 2020 15:48  

Hi Simon, sorry for the delay.

It looks like your flats are actually doing their job! The stripes you see is very likely, walking noise. If you dither during taking the images, you can get rid of that very nicely.


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