Taking Flat's

When taking Flat's, what should the setup be. I'll be using the white T-shirt method, and either doing it before sunset or dawn. I know to have the same ISO. But what do I do for the exposure time, do set it for the same amount that I'll do for the light's or do I set the camera on AV mode. Also with the focuser mount where should I have it set up, at the 0 mark halfway, or should I it at where it would be when I'm taking the lights.

devildog2222 wrote in post #11104694
When taking Flat's, what should the setup be. I'll be using the white T-shirt method, and either doing it before sunset or dawn. I know to have the same ISO. But what do I do for the exposure time, do set it for the same amount that I'll do for the light's or do I set the camera on AV mode. Also with the focuser mount where should I have it set up, at the 0 mark halfway, or should I it at where it would be when I'm taking the lights.

AFAIK, set the focus to infinity, the ISO to the same as your light frames and also the aperture. Use AV mode to get the correct shutter speed. Don't forget to use the tripod if the speed is less than 1/focal length. Note down what the exposure speed is. When you have shot your flats, put the lens cap on and set the same same ISO, aperture and exposure in manual mode. Shoot your dark flats.