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Author Topic: Flats  (Read 693 times)

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Offline Malcolm L

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Flats
« on: 22:17:28, 02 May, 2017 »
Hi everyone am new to ccd imaging ,just like to know , how many seconds to do a good flat for, when using a ccd camera or how long an exposure
 time please ?

Offline Uplooker

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Flats
« Reply #1 on: 23:13:36, 02 May, 2017 »
It's not a matter of a just a specific time. It more of what time to get a specific reading in ADUs. You are aiming to get an ADU of around 20,000 or rather the  histogram is to be 30 to 50% of the way from the LHS, without over exposing.
What camera and software are you using? Most software has the capability to run a sequence to obtain the correct exposure to attain an ADU that you specify.


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Ian

Scopes: SW 150P Newt, ST80, Celestron C8 XLT, TAL 100RS / PST Stage 2 Mod & BF10, SW 300PDS (soon to be on a Dob Mount)
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Offline Einari

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Re: Flats
« Reply #2 on: 07:29:38, 03 May, 2017 »
Adding to what Ian said - it's good to have flat exposure more than fraction of second (too short flat exposure can cause problems with some cameras).
Tapio

Celestron C8, C9.25" & Hyperstar, iOptron CEM60-EC, TS 80 triplet,  Coronado PST, SXV-694,  ASI120MM/ASI174MC Cool

Offline chris.bailey

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Re: Flats
« Reply #3 on: 07:33:34, 03 May, 2017 »
Malcolm

What CCD? CCD's with a physical shutter need flat exposures of several seconds to avoid the shutter shadowing the exposure. Otherwise its not that important.

Chris
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Offline Einari

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Re: Flats
« Reply #4 on: 08:46:58, 03 May, 2017 »
Some flat panels also have problems with short exposures.
Tapio

Celestron C8, C9.25" & Hyperstar, iOptron CEM60-EC, TS 80 triplet,  Coronado PST, SXV-694,  ASI120MM/ASI174MC Cool

Offline Malcolm L

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Re: Flats
« Reply #5 on: 13:05:49, 03 May, 2017 »
Hi guys Sorry  I forgot to say which camera am using its Atik 16ic mono and the software will be Artemis capture, I will be using my laptop
for the flats with a white t-shirt in front of the telescope if that is right.

 

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