Dark and Flat images

[Nathan593]

I am not sure how to actually take dark and flat images to put them into DeepSkyStacker with my camera. 

[vlaiv]

Darks are fairly simple to do.

You need the same settings as lights for them to work, and that means:

1. Same gain / iso / offset (depending on your camera if it is DSLR or dedicated astro camera)

2. Same exposure length

3. Same temperature

Only difference is that you have to block all light coming into the scope. You can take them while camera is attached to the scope - by covering the scope with lens cap, or you can take them when camera is detached from the telescope by putting camera cover on. Be careful about any sort of light leak - even in IR part of the spectrum (plastic can be somewhat transparent to IR wavelengths).

In case that your camera does not have set point temperature control (not cooled) - try to take darks at approximately same temperature as your image subs (lights). If your camera has stable bias and is not cooled you can use something called dark optimization (there is option in DSS for that).

Flats are done with camera on the scope and focus position roughly the same as when doing light subs. You need either flat panel or flat evenly illuminated white surface in front of the scope. You can even use sky when it is brighter (not during night, but early in the morning or early in the evening when sun is not out but it is still bright enough) - some people put white T shirt (or other cloth) on aperture to diffuse the sky light.

You need to be careful not to overexpose when doing flats. Histogram peak needs to be at about 75-80% in value.

Take flat darks as well, and rule with those is the same with regular darks, except that they need to match your flats - so same exposure as flats, same settings as flats ...