Converting Used Canon FD lenses for E420

I would recomend a Raynox (clip on) or Marumi (threaded) macro filter, not so sure about the Bower filter.

or the EX-25 extention tube... This will work w multiple lenses as long as they are about 25mm or longer (A lens below 25mm won't focus w the EX-25)
Most after market extention tubes don't have the electrical contacts, so leave you unable to focus the lens or change aperture... but would work fine with older lenses such as OM mount.

--
Art P
"I am a creature of contrast,
of light and shadow.
I live where the two play together,
I thrive on the conflict"