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Is temperature important for flats?

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#1 sbharrat

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Posted 12 June 2021 - 07:34 PM

So I understand the basics

- darks at same gain, offset, temp, exposure time as lights

- flats at same gain, offset, filter as lights

- dark flats at same gain, offset, exposure time as flats

 

But what about temperture? I am presuming that for a camera like asi533 with such low dark current, it probably doesn't matter. Suggestions? 



#2 idclimber

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Posted 12 June 2021 - 07:42 PM

I match them all if possible and it usually is. You technically can do the flats and dark flats at a different gain and temperature from the lights. I have done this when mixing targets through the night at different gains. At least that is what I was told here. The logic is the master dark flat removes all the sensor noise from the flat. 



#3 JamesTX

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Posted 12 June 2021 - 07:45 PM

No, flats and dark flats (or bias) do not need to be at the same temps. I routinely take sky flats with the cooler off.
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#4 Juno18

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Posted 12 June 2021 - 08:13 PM

No, flats and dark flats (or bias) do not need to be at the same temps. I routinely take sky flats with the cooler off.

Absolutely. Same here.


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#5 Peregrinatum

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Posted 12 June 2021 - 08:20 PM

no


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#6 Midnight Dan

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Posted 12 June 2021 - 08:39 PM

Technically, no.  But I'm in the "why not?" camp.  If your camera has a cooler, it's just as easy to take them with the cooler on or off.  I try to take all my calibration frames at the same temperature whether I need to or not.

 

-Dan


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#7 idclimber

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Posted 12 June 2021 - 09:03 PM

I keep libraries of my Dark Flats (and Darks) at the exposures that I use regularly. If the cooler is off there is a good chance they will not be matched. 


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#8 JamesTX

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Posted 12 June 2021 - 09:13 PM

Technically, no.  But I'm in the "why not?" camp.  If your camera has a cooler, it's just as easy to take them with the cooler on or off.  I try to take all my calibration frames at the same temperature whether I need to or not.

 

-Dan

 

Sure, there's no harm.  Part of it depends on when & how one takes their flats.

 

I don't like to wait for the cooler to cool the sensor down when I've already figured out the needed exposure based on the current sky.  Also, in the summer.. it gets too hot in the summers for the cooler to get anywhere near night time imaging temp anyway.

 

I keep libraries of my Dark Flats (and Darks) at the exposures that I use regularly. If the cooler is off there is a good chance they will not be matched. 

Yep.. I keep a library of darks, flats and dark flats.  I only take new flats when a new dust molt shows up... and I take new dark flats with match the fresh flats exposure time.  The temperature doesn't matter because the flats and dark flats are very short. 

 

Darks.. thats a different story.. darks must match the gain and temp of your lights.  And I have a nice library of those two.. different gains and exposures. 
 


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