On 1/14/2011 6:48 PM, AS wrote:
> Comparing the 50mm f2 and f3.5. Is the f2 a 1:1 lens? Are there different
> variations of f2?
Both "only" go to 1:2 without extension. Oly made the variable 65-116 tube, the
Auto Bellows and the 80/4 lenses
optimized for 1:1. Do you think they may have been saying something about using
the 50mm macros in the 1:1 vicinity?
My own testing with the 50/3.5 show it to be a superb lens at 1:2, sharp, with
clean edges, flat field, even
illumination and good corners. At 1:1, it's still a good lens, but clearly less
so than at 1:2
One of my first posts on this list was a question about the 50 mm lenses, and
these two specifically. In my enthusiasm,
I had thoroughly (over) analyzed Gary's lens tests. I had a short off list
exchange with Gary. I forget the details, but
I recall him saying that the 50/2 was better wide open than his test/sample
indicated.
His tests were all at 1:40, so tell us nothing about macro performance.
One thing has changed since the time when these lenses we designed. The 50/3.5
optimum aperture is f8-11. I imagine the
50/2 is perhaps f5.6 to 8, although I have no data. The contemporary Tamron
90/2.8, which focuses directly to 1:1 has an
optimum aperture of f2.8-4. It's excellent wide open at 1:2 and 1:1.
This is a mixed blessing. For flat copy work, it means more brightness. For 3D
subjects, it means a trade-off between
DOF and performance.
Moose
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