Ha flats with 414ex

[Scott]

As per title really. I've got the 414ex mono and I'm doing a run of Ha and OIII and was wondering how poeple work out the length of the flats. it was easy with the dslr, just go short. is it the same with ccd's it's my first real chance since getting the camera so I don't wish to blow it with bad flats

Thats for taking the time to read this

[johnrt]

Aim for an exposure that gives you about 22/23k ADU on the histogram.

[steppenwolf]

What johnrt said! This can only really be ascertained by measuring a test flat image as the telescope in use will affect the exposure time required.

[Scott]

ok, thanks you two... I will probably wait til tomorrow now so I can test at my leisure . I've not moved the focuser so hopefully it'll be fine. work/bed beckons

[ollypenrice]

In Aertemis it's dead easy. Just open the Display window and look at the value in White. About  to 20 to 25 thousand works for me.

Olly

[lensman57]

As per title really. I've got the 414ex mono and I'm doing a run of Ha and OIII and was wondering how poeple work out the length of the flats. it was easy with the dslr, just go short. is it the same with ccd's it's my first real chance since getting the camera so I don't wish to blow it with bad flats

Thats for taking the time to read this

 The 22~23  thousand ADU value should be the starting point. The ADU value of the flats depend on the well depth of the CCD, so do some between 20000 ~30000 ADU and see which one works best with your set up.

A.G

[MattJenko]

I have been using a Lum flat for pretty much all my filters as I am lazy and it works well enough with my 414ex and Baader filters all tucked up nicely in a filterwheel.

[MattJenko]

I have even manually resized my flats last night so I can use them with binned 2x2 data and it works a treat.