Archived posting to the Leica Users Group, 2000/10/24
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At 7:14 PM +0200 10/24/00, Pascal wrote:
> >Sorry to hear that. I'd be more interested in a 12 than a 35 from
>>another manufacturer.
>
>well, it's not as if the Ultra Wide Helar 12mm f/5.6 Aspherical were a
>bad lens, but I feel I could have been better when I see the chart.
>Optimum f-stop= f/8, with very good to good results.
>
>Lots of vignetting, however, even at f/11 where it is still one full stop
>and thus excessive. This is the real issue and will limit its practical
>usefulness.
>
>Pascal
>NO ARCHIVE
>
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Actually, it has more than one stop falloff. It has _slightly_ more
falloff than the 15, which has a noticeably greater degree of falloff
than the 21 ASPH, or about the same as the 21/3.4. In practice I
don't find the light falloff that important, but I will try to get a
center filter to fit as soon as I get the filter adapter.
BTW, the 21 ASPH has about one stop falloff center to corner even at
its best aperture, let alone wider. Most tele lenses have more than 1
stop falloff at their wider apertures. The 90 Apo-Asph is the
outstanding exception to this.
General optical performance is on the same level as that of the 15,
and in the 12, the level of flare control is truly amazing,
expecially to anyone who has shot with any SLR 15's or 14's. I
haven't shot enough with the 15 S-Elmar, so I would have to leave
that out of the discussion.
The DOF scales are truly optimistic. They are calculated to the usual
rules, but as is usual with wideangles, one tends to look closer,
often because the details are smaller, and DOF generosities show up
quickly. Try to set the distance of whatever is important accurately,
and let the DOF handle the rest. Don't try hyperfocal stuff.
Resolution and contrast are very good, and distortion seems to be
extremely low. This is hard to check as you have to be very close to
something to get it to fill the frame, and the object you are
photographing has to be truly linear on both axes. Not always
available even on architectural subjects.
The images that it produces are sometimes hard to relate to, as _so
much_ is in the corners. I find it still hard to handle, even though
I have had 15mm lenses contiuously since the early 70's. Those extra
3mm do make quite a difference.
- --
* Henning J. Wulff
/|\ Wulff Photography & Design
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