Gene Wilburn wrote:
>I have an old Vivitar 2x converter for OM lenses -- dating from
>probably around 1973-74. I always notice some degradation when I use
>it but accept that as typical. Has anyone ever compared one of these
>to the Zuiko 2X-A 2x converter. Is the Zuiko significantly better in
>your opinion, or is it a tossup?
>
Assuming you are talking about the old 4 element converter, 26mm barrel
and usually marked 2X-21, it is typical of 4 element converters, not
unusable stopped well down, and pretty bad opened up. I too used one
back then, with pretty much the same results you got. Best used with the
elements removed as an extension tube.
7 element converters were significantly better. They came under many
names, but usually with MC7, MC-7 or something similar as the model.
Pretty much all but the Tamron look like they came out of the same
factory, rather nicely made and finished, about 41mm long.
All of these will fit pretty much any lens and work rather well. The Oly
2xA is a cut above those generics in performance, but will only fit
certain lenses <cid:part1.05010708.01000702@moosemystic.net>. A couple
of other lenses can be slightly modified to fit the 2xA, but results may
disappoint, as you can see in Gary's test of the 90/2 with the 2xA
<http://members.aol.com/olympusom/lenstests/default.htm>. If you look
further down in the tests, you will see several lenses tested with the
2xA, with interesting results. The tests with OM-1 were pretty awful.
Those with OM bodies with mirror and aperture prefire and some care
about vibration control are often quite good. The 135/2.8 is as good
with as without the 2xA and the 135/3.5 is better with than without! The
200/4 also does rather well with the 2xA and vibration minimization.
The 2xA, used with the recommended lenses, at least the primes, and with
care to control vibration, is capable of excellent results. Gary's tests
also show it working well with some of the later f2 teles. It also works
rather well with the 300/4.5 using vibration control. My TOPE 20 shot
uses this combo. Of course, it's not possible to really judge sharpness
at those display sizes, but the original is quite sharp. I didn't use
aperture/mirror prefire. I used the technique Oly recommends for all
teles, " When using a tripod, hold the camera steady with both hands and
press the shutter release with the ball of finger, not with the cable
release." The one thing they leave out that I think is important is
pressing down gently, but firmly, on the camera so vibrations in the
head and tripod assembly will be damped too.
Moose
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