light frames for different filters

[woodblock]

I have a monochrome camera which I use mainly for photometry work. I recently bought a filter wheel which works fine. I have two filters - Johnson B and V. I wondered if you need separate calibration frames for different filters. I figure that the darks shouldn't matter because they are, well, dark. But what about the light's? Should I have different light frames for different filters?

 

Cheers

Steve

 

[TerryMcK]

Hi Steve,

I don't do photometry but imagine it is the same when acquiring data as conventional astrophotography. In that case we do indeed get separate calibration frames for each filter to remove dust motes and correct vignetting. Each filter will of course let through different wavelengths and you need corresponding flats for calibration.

As you quite rightly say darks are darks and you only need one set of the same exposure duration/gain/offset that match the lights.

My cameras don't need bias frames so I never bother with them.

 

[woodblock]

Thanks Terry, since flats are needed because of dust motes I think that probably means that I'll have to redo all my V filter flats again since the filter itself is mounted differently. Up till now it was mounted in the camera itself but now it'll be in the filter wheel.

 

Steve