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Old 01-02-2009, 07:51 PM
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TrevorW is offline
Join Date: Aug 2006
Posts: 6,995
No offence taken but I believe that in certain situations and if you use the same ISO setting for all your images note ambient temperature at the time etc a library of darks and flats can be build up over time which may be applied to lights as and when needed (by flats I assume your referring to an absolutely white image)

Moreso it is not 100% necessary to take your darks at exactly the same time you take your lights(subs) by more importantly at the same ambient temperature give or take a degree or two as expressed by another noted astrophotographer.

and I quote

"Trev, as for the darks: in 1x1 I do not use any darks at all. and for the 2x2 binned images I try to take the darks at about the same temperature +/- 1or 2 degrees. so, it is not essential to take the darks at the same time, but merely at the same ambient-temperature.

Starlight Xpress CCDs do not feature temperature-control, soI have a thermometer in my obs and I pay attention to it closely


I also asked:

"Would I be correct in assuming that this can also apply to DSLR photgraphy in that

darks may be taken at at different time than the image frames as long as the ambient temp when taking the darks is within 1 or 2 degrees (or is their a greater temp differental that may be used) of when you took your image frames"

and the reponse

"basically I’d say yes.
All it is a bout is that the sensor is exposed to the same ambient conditions when taking the darks, as it was exposed when you took the lights, trev.

Dietmar Hager, F.R.A.S."

I was wondering are there others who may have accumulated darks and flats into a library of sorts for use ad hoc on those occassions where weather or something causes them to miss taken these are the same time.

Last edited by TrevorW; 01-02-2009 at 08:14 PM.
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