You will lose something in the optical quality but that's true any time
you interpose another optical element. You'll have to be the judge of
whether it's significant or not. I have a Vivitar 70-150 f/3.8 with
matched multiplier. The "matched" means that the multiplier was
designed expressly for this lens so should give very good performance
relative to any other multiplier. I rarely use it but that has nothing
to do with the quality of the glass.
The biggest problem in my book is the loss of f-stop. A 1.4X multiplier
gives you a one stop loss, a 2X multiplier a two stop loss. If your OM
75-150 is a 3.5 then installing a 2X multiplier gives you a 150-300
f/7. However, the optical performance at f/7 is really the performance
at 3.5 (wide open) slightly worsened by the multiplier. Even if the
performance at this or the taking aperture is plenty good enough you
still have to focus at f/7.
If you use fast film on sunny days it might be fine. Having said all
that I do still use it once in a while since the longest lens I have
otherwise is an OM 200mm f/4 (if you don't count the 2000mm Celestron
:<)
--------------------------------------------------
Date: Sat, 27 Mar 1999 01:27:31 -0600
From: "Kinkead, Frank W" <Frank.Kinkead@xxxxxxxxxxxxx>
Subject: [OM] Tele-Converter
Do any of our group have strong opinions regarding tele-converters ? My
longest lens is the OM 75-150MM. I'm considering a tele-converter for
that
lens as an economical alternative to a true longer lens. Do I loose
significant f stops ? OM's tele-converters are available used at
reasonable
prices; other makers converters are dirt cheap. Are these non-Zuiko
ones
particularly undesirable ?
Thanks,
Chip Kinkead
St. Louis, MO
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