73930Re: [ccd-newastro] Do Dark and Bias Frame patterns change as the camera gets older over time?
- Feb 5, 2014it's not just those hot pixels; all of the pixels drift to some extent. Some are just more obvious.The only way to know how much, of course, is to compare sets against each other.Ron WOn Feb 5, 2014, at 7:29 PM, Tim Stone <tim.stone.piano@...> wrote:I do believe the electronic characteristics of a CCD (can't speak for CMOS) changes over time. I notice new column artifacts, hot pixels, and such every now and then. When your calibrations are leaving these artifacts in the images, it's time for new calibrations. I'm with Mark... I tend to do new darks in December and June (cloudy nights, of course). Ambient temperature seems to affect them, and so I try to use darks that are no more than six months old, taken at the operating AND ambient temperature (average) I expect for the next few months. In other words, darks shot at -30C operating temperature with 20C ambient (50C delta) are less useful than darks shot at -30C and 0C ambient, if tonight's temperature is 0C. That's my humble opinion...~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Tim StoneOn Wed, Feb 5, 2014 at 8:45 PM, Mark Acker <markacker@...> wrote:I think most take darks no more than about every 6 months or so. Bias, since they take no time at all, can certainly be made anytime. I will certainly defer to the experts in this forum, but that's about how ofter I redo them.Mark Acker
From: cpatel823 <cpatel823@...>
Sent: Wednesday, February 5, 2014 6:42 PM
Subject: [ccd-newastro] Do Dark and Bias Frame patterns change as the camera gets older over time?
Hi, I searched for an answer but cannot find a posting that speaks specfically to this. I took a library of Darks and Bias frames back in 2007. I try and adhere to specific temp and time parameters (15 minute exposures at -X degrees, while imaging to match images with reduction frames. My question is - Its been 7 years so do Dark and Bias frame patterns created by a camera change over time and should I recreate my library?
Thanks for your input - Chris!
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