Fellow Zuiko-technicals,
Here is a question:
On some Zuiko lenses, for example the 35mm f/2 and the 85mm f/2, the aperture
ring does not have an equal spacing for all the f-stops. The first gap
between f/2 and f/2.8 is smaller than the subsequent gaps.
This results in the aperture ring turning through a smaller angle, even
though the difference is 'one f-stop', the same as all the other intervals
(or is it?). At the same time, the coupling lever which 'tells' the camera
the f-stop (am I right?) moves through a smaller angle, and the needle meter
on my OM-2N and the LCD display on my OM-4Ti both register a smaller change
in corresponding calculated shutter speed in AUTO exposure, presumably
because the meter has been 'told' that the change in aperture is smaller than
1 f-stop.
Why is this so? It makes me wonder if these lenses are _really_ as fast as
f/2.
I presume that they are, and there is maybe another overriding technical
reason for these short gaps (maybe connected to the aperture blades or
metering system?)
Here is another question:
I have seen a possibly related thing on other manufacturers' lenses too. And
sometimes, I think that allegedly f/3.5 and f/3.8 lenses are 'just about'
f/4, because I can see at most 'hardly anything' of the aperture blades if I
attempt to 'stop down' from wide open to f/4. If I can't see them from the
front end of the lens, how can they be blocking any incoming light?
What do you reckon? All answers/comments appreciated.
Dave Bellamy.
http://members.aol.com/synthchap/
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