Dark Frames with a Filter Wheel

[carastro]

how would i know its been taken properly......

You can stretch the master dark brightness and contrast I normally use and if you can see vignetting and dust then you've exposed it OK.

If you are using software that will let you read the ADU of the flats I always try to get somewhere around 21,000 ADU (some people like 25,000 ADU)

Carole