on 4/19/02 7:08 PM, Richard F. Man at richard@xxxxxxxxxxxxxx wrote:
> But C/C+ at /2? That's the point of getting a /2, isn't it? Lets see..., at /2
> 21/2 .... B+/C
> 24/2 .... C+ / C w/ mirror up, prefire...
> 28/2 .... B / B
> 35/2 .... B, and C- at corner
> 40/2 .... C / C
> 50/2 .... C / C <-- wow! That low?
> 85/2 .... C+ / C+ --- B+/B- w/ mirror up, prefire
> 90/2 .... B+ / A <-- whee, no wonder it's so good :-)
> 100/2 ... C+/ C+
> 180/2 ... A/ A- <-- WOW!
> 250/2 ... A / B+ <-- wow!
>
> OK, so I was assuming incorrectly that at wide opened, the performance will
> not be generally much worse than /2.8, /4, but looks like Cs are the norm,
> or average, or is it "mean"? Arrghh...
>
> Looks like the 180/2 and 250/2 though, are just outstanding. May be I will
> sell one of the cars (ha ha, a joke).
The /2 aperture is helpful in focusing, especially in lower light
environments. Not only do you get a narrower zone of sharpness due to the
lesser depth-of-field, but you also get a brighter screen image to use in
evaluating the zone of focus to make sure you are focused where you want.
Split-image devices and microprisms also work better. I don't think you can
see the difference in the finder between an "A" and a "C" except maybe in
very subjective and subtle feelings of less crispness.
I suspect that how solidly you hold the camera and the shutter speed have as
much influence on the sharpness in many images... would the extra stop or
two of shutter speed offset the lower sharpness of f2 over f2.8 or f3.5?
Unless using a tripod, I think I can get sharper images at f2 and 1/60 than
I will at f3.5 and 1/15...
--
Jim Brokaw
OM-1's, -2's, -4's, (no -3's yet) and no OM-oney...
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