Originally posted by mrNewt If you really want to use an UV filter in "bad" conditions, you can also buy 1 large very good (expensive) UV filter and then just purchase step-up rings for your lenses - that are very cheap.
I agree, and I carry some step-up rings so that I don't need so many expensive filters. (I buy some filters in 67mm and 77mm, for example Circular Polarising and 9-stops ND, and some in just 77mm, such as Singh-Ray Gold-n-Blue, and an Intensifier).
In the case of the UV filters, I already had expensive ones, which I then stopped using, on all my lenses. So I carry a set of them.