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As I have stated before, the comment by Kato-san is correct _only_ if you know what you are doing. Most fields do not have a good blue comparison star; many objects have nearby companions that get included in the photometric aperture; systems may have different color at quiescence; features in the light curve can have different appearance at different wavelengths, etc. It depends on what you want from the dataset and with what accuracy. I still recommend starting with unfiltered photometry, but then seriously considering using a standard filter and perhaps restricting your projects to those fields that you can do well with the lesser throughput. Note that I am not advocating against unfiltered photometry, just that it is not the panacea that everyone desires. For many projects, unfiltered photometry requires more care in analysis than equivalent standard-filter photometry. Arne Taichi Kato wrote: > Re: (fwd) to V or not to V - I couldn't resist it > > In unfiltered CCD photometry, no special conversions are necessary for > CVs (particularly disk-dominated objects) having colors close to B-V=0. > Selecting a blue comparison star, the color effect is in most cases mininal. > In very special cases, we need to correct secondary color terms. > > Regards, > Taichi Kato > > >
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