On 4/6/2010 5:56 PM, Ken Norton wrote:
> ...
> Hmm. I have a theory starting to emerge. I carefully duplicated the test
> sans-film with the OM-4T on my laptop screen using the spot-meter mode and
> observed that the F1.4 position was 1/3 stop off from the other apertures.
> This is much better than the 2/3 stop of the E-1. Therefore, I got to looking
> at the cameras a little closer.
>
More like what I would expect from my rough iris size measurements.
> The exit pupil of the 50 F1.4 is rather huge and the mirror chamber of the
> E-1 is tiny in comparison. What I'm thinking here is that the actual mirror
> chamber itself isn't large enough to support maximum aperture of the 50
> F1.4. As to the spot-metering of the OM-4T being off by 1/3 a stop, just
> maybe the same thing is happening there too.
>
> ... My current theory is in-camera vignetting which has nothing to do with
> the lens. If so, this is a problem for regular FourThirds cameras, but with
> the shallow chamber of the MicroFourThirds, it might be just fine.
>
I'm not sure about that theory. I had the same idea, which seemed
sensible. But I observed similar behavior on the 5D.
BTW The rear element of an older Nikkor 50/1.4 is the same size as the
Zuiko.
Moose
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