73939Re: [ccd-newastro] Re: Do Dark and Bias Frame patterns change as the camera gets older over time?
- Feb 5, 2014I think one thing that differs here is that you operate from a perm setup, while I am mobile only, which I probably should have made more clear. It's not practical for me to take darks as soon as I finish a night of freezing my whiskers off. :) Also, I only cool to a multiple of 5 degrees, with the exception of 1, 2, 3 minutes for things like M42. Frankly I'm not at all sure that I could recognize the difference in darks taken 3 degrees off from the lights anyway, which is why I stick to predominately multiples of 5.Mark Acker
From: Mike Dodd <mike@...>
Sent: Wednesday, February 5, 2014 9:47 PM
Subject: [ccd-newastro] Re: Do Dark and Bias Frame patterns change as the camera gets older over time?
Mark Acker wrote:
> I think most take darks no more than about every 6 months or so.
I used to do that, and kept a library of darks. But I stopped when I
found myself cooling the camera to temperatures that didn't match my
"standard" camera temperatures (e.g., -15C, -20C, -25C). If I could
reach, say, -18C in the camera, I wouldn't have a dark to match. So I'd
set the camera to -15C, "wasting" any reduced noise that extra 3 degrees
would have provided.
This also applied to exposure times. A library of 10- or 15-minute darks
isn't much help if I can make 17-minute light exposures one night.
Instead, I began taking a set of 10-15 darks immediately after my target
went behind the trees. I keep these darks with the light frames, and use
them just for processing that target. I'm always assured of darks with
the correct exposure and temperature.
In short, I found maintaining a good dark library to be not worth the
effort, especially when I started using ACP automation software, which
will take my darks without any action on my part.
Louisa County, Virginia USA N37.58.23 W77.56.24
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