In article <5esfgp$mp2@rock.me>, weage@mtu.edu says...

> Just to see what was going on, I took the filter and
>held it in front of my 50mm lens. The focus didn't change
>at all. Makes me wonder what is going on. Maybe I don't
>really have that 200mm lens back together correctly, even
>though it focuses fine at infinity without the filter.

Any defect in the filter is magnified by using it on a
longer lens - if the focus shift and image softening
in the finder image were barely detectable with the 200mm
lens, it is not surprising that they are not detectable
when the filter is placed on a 50mm lens instead of a 200mm.
(Try shooting through window glass with the 200mm and the
50mm - the image will be sharper shot with the 50mm [and
sharper yet shot with a 24mm...]).
Hope This Helps