"I purchased OM4Ti + Zuiko 200/4 + 28/2.8. When testing camera with focus at
infinity (antenna that is at least 3 blocks away, with standard split-image
screen), I found that antenna comes in focus before actual infinity mark on the
lens is reached (~1.5 mm before reaching infinity mark)."
As has been explained previously, all lenses vary slightly in focal length from
their nominal values, and the focal length can change with temperature
(especially with longer lenses). Therefore, most lenses are designed to focus
slightly "beyond" infinity to allow for these variations. There is probably
nothing wrong with the camera.
I do agree, however, that 3 blocks (about 100m) is not quite "infinity" for a
telephoto lens.
"Someone posted a while back that split prism/microprism focusing is not as
accurate as matte or cross hairs. They had some justification for this."
The writer's camera had a split-image screen. And split-image is quite accurate,
because the human eye is very good at detecting tiny "breaks" in vertical lines.
"Have you tried to adjust the dioptric lens of the viewfinder according to your
eyesight before mounting the lens?"
The diopter setting has no effect on how the lens focuses on a matte screen or
split-image/microprism screen.
"It could also be that the focus plane at the screen is different to the focus
plane at the film, in this case you will not get optimally sharp results and the
camera must be calibrated."
A film-plane/focus-screen discrepancy will _not_ cause visible focusing errors
_in the viewfinder_. The focusing screen doesn't "know" that the film is
mispositioned.
>>>>>
Thanks to Per Nordenberg for listing the new features of the IS-30. Although
Japanese companies sometimes drop features from their US cameras, it's usually
due to patent conflicts. Unless you have to pay royalties, it's almost always
cheaper to sell the same camera in every country.
If the IS-30 has Super FP flash, more-sensitive auto-focus, and exposure
compensation, I guess I'll just have to start saving up. And -- hey! -- the
IS-30 appears to be black and gray -- not champagne gold. Hallelujah!
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