IDAS LPS P2 and Baader UV/IR cut / L filter

[alcol620]

Hi folks

A bit of clarification required.

I have been using a IDAS LPS P2 filter ahead of the 0.85 reducer/flattener on my 80ED set up (using a DSLR camera). I have aquired a filter wheel and a Atik CCD mono camera and a filter wheel. The filters to be used include a Baader UV/IR cut / L filter.

Does the IDAS filter still perform a useful function?

Thanks for looking

[Thalestris24]

Hi

Yes, if you have lp that you need to filter. I would imagine you don't need the UV/IR cut so much but maybe you have to have it to maintain parfocality?

Louise

[Ikonnikov]

Having done some research on this subject recently the consensus seemed to be that both luminance and RGB filters benefit from the use of the IDAS LPS P2 in the imaging train with mild to moderate light pollution (although some people still prefer to remove LP by processing alone and others use the IDAS as the L filter). Since the IDAS acts to block UV and IR, a clear filter may be the best option for L subs since it would have the highest light transmission (though I doubt it would be that much better than the UV/IR filter). As Louise mentions above, having an empty slot for L would result in a different optical distance compared with the colour filters and this would cause a significant change of focus position and also upset the correct spacing between the CCD chip and the reducer (assuming it is correct when the R/G/B filters are in place) potentially resulting in increased aberrations.

Paul

[alcol620]

Thanks for feedback

Will keep it in the train for the moment