OK, so here is my test:
1. Mount lens to E-1 via genuine OM-43 adapter
2. Set focus to infinity
3. Set camera to manual exposure
4. Set ISO to 100
5. Set aperture to F16
6. Set shutter speed to 1/4 second.
7. Hold lens up flat against LCD computer monitor with white background
8. Take picture.
9. Open up one stop
10. Adjust shutter-speed down one stop
11. Take picture
12. Repeat 9-11 until done.
Comparing histograms and general appearance (this isn't my first dance with
a camera), I'd say that all images are within 1/8 of a stop of each
other--which is what I expect to see from the E-1 as there is a little bit
of exposure slop with it. (10 identical pictures will have a couple exposure
variations). However, the final one at F1.4 is underexposed by 2/3 of a
stop, which is exactly what I've been seeing all along with the exposure
meters.
Carefully examining the lens, the aperture blades at F1.4 are fully
retracted and behind the round shroud just in front of the blades. So there
is no evidence whatsoever that the blades are getting hung up at all. None.
So, what am I to make of this? No, Bill, I'm not returning the lens and I'm
not disappointed, I'm just wondering about this little mystery in life which
I've noticed with other lenses too. The Zuiko 50 F1.8 is an F2 in my
experience and my old Zuiko 50 F1.4 was the same way.
Hey, on a positive note, this late-model F1.4 lens is EXTREMELY sharp.
Eye-popping sharp!
AG
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