Hello all,
I have an off-brand 500mm f/8 mirror lens (Lentar)that was purchased by my
dad in the early '80's for his Pentax. A year or 2 ago I got a t-mount
adapter for Olympus and began using it on my Om-2n with success. A couple
of months ago, the spring on the release button went out, and rather than
try to fix it, I bought another mount. After installing it and adjusting
the mount so that the lens was in the right position after mounting, I
mounted it on my OM-4ti on a tripod and pointed it out the door in the late
afternoon sun loaded with 100 speed slide film at some birds in a tree. (I
made sure the t-mount wouldn't harm the reset button!). It was in auto mode
and the speed indicated (at what should've been a fixed f/8 aperture) was 1
second or more. That didn't seem right for the Texas afternoon sun, so I
mounted a 200mm lens on the camera, set it at f/8, and pointed it at the
tree. I got about 1/60 for the shutter speed. I pulled the 200mm and
compared the aperture levers on the backs of the lenses (that transmit the
f-stop setting to the body) and they appeared to be at about the same
relative position. I then performed the same test with an OM-2 in auto
mode, and my OM-1, and got the same results. On the OM-1 there was about 4
1/2 stops difference between the 200mm set at f/8, pointed directly at the
large light globe on the ceiling fan and the 500mm. What am I missing or
doing wrong? Shouldn't f/8 be f/8 for the same light with different lenses?
I had never noticed this problem in the past, and had gotten good results
with the OM-2n on slide and print film in auto and metered manual modes.
Thanks for your help!
James Kiker
james.kiker@xxxxxxxx
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