Flats - im sure this has been asked before

[zakkhogan]

all i want to know is, do i shot at the same iso as i do lights\darks ?

from what i understand i need to reducer the exposure to a minimum, is that correct?

Thanks

[ollypenrice]

You don't have to shoot flats at the same time but you need to avoid changing anything in your setup. The camera angle and the focus must not change and no new dust should be allowed onto any filters etc. So doing them fairly close in time to your lights is safest. Probably do them at the same time if you do not have a permanent setup?

Your exposure time should get the flats to be exposed to about a third to two thirds of saturation. (The peak in the histogram should be a third to two thirds of the way to the right. Personally I prefer a third of the way.) This will not be the minimum your camera can do if using a sensible light source.

Olly

[steppenwolf]

As Olly has said plus you don't have to use the same ISO setting

[zakkhogan]

thanks olly\steve

when you say "The camera angle must stay the same", does that mean i can not slew the scope or are we talking about the camera body's position in the assembly?

cheers craig

[Photosbykev]

They are referring to the relative positions of the items in the imaging system and also the focus position

Sent from my iPhone using Tapatalk. Blame Apple for the typos and me for the content

[RikM]

Don't change the orientation of the camera in the focuser or change the focus position very much. Slewing the scope (e.g. back to the home position) should be okay. I always take flats at the same iso as the lights just in case. Same with darks and bias. I don't know if it matters for the flats, but (if you take enough of them) it doesn't hurt either.