Quote:
Originally Posted by White Rabbit
To take flats you need to do it on the night you take the images, beause of temp and also camera angle.
Thanks
Sandy
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Hi Sandy
Although in practice your Flat Fields will generally be taken at the same temperature as your Light Frames, I don’t think that temperature is quite as critical for taking Flats, other than your tube and focuser may expand/contract with large temperature variations and hence may alter the focus slightly.
However, the same temperature is critical for Light Frames and Dark Frames; that is, your Dark Frames should (ideally) be taken at the same temperature and duration (exposure) as your Light Frames.
Dark Frames characterize the thermal noise and other unwanted sources of electrical noise of the sensor and associated circuitry.
Light Frames characterize the overall optical “quality” of your imaging train; that is, vignetting, gradients, dust spots, etc.
Cheers
Dennis