Dark Flats

[Chris Southby (Chris)]

Hi all

I have been trying to find out how to do dark flats, I can work out dark frames and light frames but what is a dark flat.
All the web sites I have looked at talk about using them in processing but not how to take them.
hope this is not a silly question.

Cheers

chris

[DavidU (Dave)]

Flat frames - Attach light box to the telescope and take a number of bright flat exposures with an integration time giving the average signal corresponding to about 1/3 to 1/2 of the dynamic range of your camera. Then cap the telescope and take a set of flat dark frames with the same exposure time.


Hope this helps

[Octane (Humayun)]

Chris,

Treat your flat darks as you do the darks for your lights; same exposure duration as your flat light frames.

Be sure to put your lens cap, or body cap, or telescope cap on, and make sure your viewfinder is covered to avoid stray light coming in.

Regards,
Humayun

[citivolus (Ric)]

My brain finds it easier to understand them if I think of them as dark flat frames

[tlgerdes (Trevor)]

I always got to understand them as exactly the same as flats except that you put a cap over your lense or scope.

So easiest way is set up to take 10-20 flats, take them, then put your lense/scope cover on and take them again as 10-20 dark flats.

[g__day (Matthew)]

The explanation that worked best for me - there are a dark shot of exactly the same duration as your flat frame light shots are. So if your flat frame were 1/20th of a sec - your dark flats should also be this duration - but taken with the lens cap on. If your flat frames were 1 second shots - then your dark flats are one second with the lens cap on too.

[Chris Southby (Chris)]

Thanks Guys
The replies have cleared up this query. Its a great source of infomation and help.

Cheers

Chris