Taking flat frames for HaRGB

[jazzin]

When shooting flat frames for HaRGB, do you shoot flat frames for each filter or just one set of flats is good enough?

Going to try HaRGB tonight for the first time and am wondering

Thanks

[Graeme1858]

You will need flat frames for each filter. Firstly because the exposure will be different for each filter and secondly because the possibility of dust will be different for each filter.

Once you're set up to take the flat frames it won't take too much longer to take them for each filter though.

Good luck.

Regards

Graeme

[STEVE333]

Also, you may at times bin differently for the different filters. Many users bin Ha 1x1 while binning RGB 2x2. The flat frame needs the same binning as the Light frames.

Steve

[UlteriorModem]

There is a time saving stratigy, if you can reliably repeat the optical train orientation.

That is to create master flats and use them for a few months or something changes. It's a good project for a cloudy night. Capture sets of flats for each channel and create a master flat from them for each channel. The flats can generally be re-used for a good period of time.

[yobbo89]

one set of flats borderline will help with vignetting,i do this and can just process out other defects in processing, but what's better and what should be done is flats per night per filter with every time you have an imaging session due to dust particles which can move around in the imaging train .

[UlteriorModem]

If the filters in inside a filter wheel there is not much dust going to get on them. There pretty well protected from 'exposure'.

When I used to do LRGB I would use the same set of flats for months. Unless a new dust doughnut popped up somehow.