I'm more than a little irritated about the negative responses to my correct
explanations of full-aperture metering.
If you were going to design a camera that read exposure at full aperture, what
would be the first approach that crossed your mind? "Obviously" it would be to
have some mechanism for telling the camera what the lens's maximum aperture is.
Nikon used this system (at least on the Photomic FT and FTn finders).
This approach -- in which the aperture-position pin is always positioned at the
same f/stop (f/5.6 on Nikon lenses) is what I was talking about when I said:
> Let me rephrase the question this way:
> "How can you get full-aperture readings when the lens doesn't seem to have any
> way of telling the camera what its maximum aperture is?"
Indeed, this is a legitimate question. How can you? Why _shouldn't_ the camera
have to "know" the maximum aperture to deliver correct meter readings?
A bit more thought shows that there is another way to take full-aperture meter
readings. Instead of placing the aperture-position pin at a particular f-stop,
you can reposition it to compensate for variations in the lenses' maximum
apertures. Minolta was probably the first company to do this, and it's the
system OM cameras use.
I was surprised at the generally incorrect responses to the original question,
the most-common being that, since the meter reads through the lens,
compensation is automatic. Well, it ain't.
I'm tempted to stop posting anything of technical nature, as it seems necessary
to write a 2000-word essay on any and every subject, spelling out everything in
excruciating detail so there is no question whatsoever about what is being
discussed. I just don't have time for that.
"Think, people, think!" -- Lex Luthor
>>>>>
"Those of you who have a June catalog of B&H (these may be on their Web site),
look at p.13 and p.99. Granted that these are digital and video camera
conversion lenses, I would think that some of them are adaptable to OM Zuiko
lenses or for that matter to the front of the zoom lenses in the IS/L series
cameras."
Several years ago I bought a Sigma wide-angle converter lens for my camcorder. I
decided to try it on my IS-10.
Whoops! No good. Not only was there visible distortion, but there was a quite a
bit of visible chromatic aberration -- enough to be completely unacceptable even
in a 4x6 print.
Proceed with caution.
>>>>>
The first time I saw this 12345xxx format for serial numbers was in ads for used
Leica lenses. The reason? You don't want to publicize "real" serial numbers so
that dishonest people can use them to make fraudulent insurance claims.
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