But won't focus change just slightly from night to night because of different thermal conditions? Richard, from Stellar Technologies International says to check the focus when changing to a different target because the telescope may cool and focus may change slightly. I guess you could reuse flat frames if the imaging nights are spaced close together but I would redo them from month to month. Debbie
From: Patrick Wiggins <paw@trilobyte.net> Date: 2005/11/22 Tue AM 10:40:57 MST To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Subject: Re: [Utah-astronomy] Flat Field Frames
Joe Bauman wrote:
I hope someone could explain more about flat frames. I know what they're supposed to do. My question is, why isn't it good enough to take one set of flat frames, and then have them to reuse forever? Or is it good enough? Thanks, Joe
Morning Joe,
This comes up on the Software Bisque groups from time to time.
My understanding is that you can resuse flats _provided_ the focus is at the exact same place and the position of the camera and any focal reducers are in the exact same position.
But if any of that changes, even a little, a new flat must be made.
Patrick
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