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>My local camera dealer sold me a Rilex skylight filter to go on my >$700 Nikon lens. He swore that it was just as good as the more >expensive filters because it was made by the same people. I know that >is an oft used line. But I believed him. It was 35% less than the name >brand ones. It seems to work out just fine. But I can't seem to put to >rest this nagging suspicion that it is actually, somehow, sucking the >quality out of my expensive Nikon glass.
Hmmm.... "Rilex"... Haven't heard of that one. Here is a simple
test you can do to check the filter: place the camera and lens
on a sturdy tripod aimed at distant detailed subject matter. If
the lens is a zoom, use it at the long end. Use a slow film. Focus carefully and shoot a frame with the filter off with the aperture
wide open. Carefully remove the filter without disturbing focus,
and take another frame. Repeat this several times, keeping track
of which frames are which. Refocus for each pair, alternating pairs
to minimize filter removal/replacement, and to switch which filter
condition is first in the pair. (If you have a good longer lens that will fit the filter, use it instead for a better test of the filter.) Examine the film (of any type) directly with a good 10X magnifier
(a cheap chrome-case folding field magnifier works fine - use it over
a large, even light source). If you see no difference on the film
with or without the filter, stop worrying. If the filtered frames are consistently slightly less detailed, return the filter.
BTW, if you care about color matching between Nikkor lenses, it is a good idea to use the same (good) filter brand and type on each lens.
Even UV filters often have a little color, and can vary in color from
one brand to another (though there is more color variation in skylight
filters). Also BTW, Nikkor filters are excellent, with Hoya being
an excellent cheaper alternative.
Hope This Helps