[Leica] Zeiss ZM 21 & CornerFix

[mark at rabinergroup.com (Mark Rabiner)]

Did not mean to imply the filters would be better than this software.
I was just bringing it up. I know the issues involve more than just
lightening the corners which his all a filter could do. But color issues.
Fringing perhaps is the word.

-- 
Mark R.
http://gallery.leica-users.org/v/lugalrabs/winterdays/


> From: Paul Roark <roark.paul at gmail.com>
> Reply-To: Leica Users Group <lug at leica-users.org>
> Date: Tue, 17 Jan 2012 08:46:06 -0800
> To: Leica Users Group <lug at leica-users.org>
> Subject: Re: [Leica] Zeiss ZM 21 & CornerFix
> 
> Mark Rabiner <mark at rabinergroup.com> wrote:
> ...
> Center filters is what
> symmetric glass are said to need and there's been a
> cottage industry making
> them for decades for all the finest lens
> manufacturers making symmetrical
> lenses notably the German ones Rodenstock
> and Schneider (JSK) for view
> cameras.

All that I've seen so far are too large for the 21mm Biogon
> (46mm
filter size).  Ideally, I agree that would be the best way to deal
with
> light fall-off, but in practice, I think I'll end up relying on
CornerFix and
> possibly multiple exposures.

So far, the increased noise in the skies near
> the edges and corners
has been the main visible artifact.  Increasing the ACR
> noise
reduction -- color and luminance -- in a second "development" of the
DNG
> has given me the smoothness needed to deal with the noise.  (I
don't use any
> luminance and restrict even color noise reduction in the
main DNG conversion
> to avoid softening of details.)

Paul
www.PaulRoark.com




> Though a modern
> retrofocal lens like the 21mm f2.8 Elmarit M ASPH is so well
> corrected after
> years of computer design that they almost emulate a true
> wide angle lens
> like a Biogon or SA. But I think almost not quite as far as
> correction goes
> say for architectural use a symmetric is the lens of choice.
> And its a shame
> the are monsters which weigh a ton comparatively.
> But gee there is no fall
> off an the edges.
> Me I'd buy a center filler which gave you fall off on the
> edges as I darken
> the edges on every image I ever make first in the darkroom
> and now digital.
>
> Sheet shooters love a Biogon or super Angulon with their
> amazing low profile
> compactness and don't mind the amazing lack of
> distortion at all.
> Witness the amazing history of SA use on Leica M.
> There
> have been more than a few shooters who shoot Leica M only for that
> reason. A
> few on the White House staff. With a nikon with a 105 on one
> shoulder and a
> Leica M4 with a 21 3.4 SA on the other.
> I've yet to score one I borrowed a
> modern Hassy superwide for a week and did
> lots of shooting with it. Much of
> it on a tripod with the camera carefully
> leveled. And at f11 with everything
> zone focused from 3 feet to infinity.
> I'll love it when I can work with a
> true wide again. As in own one.
>
> --
> Mark R.
>
> http://gallery.leica-users.org/v/lugalrabs/winterdays/
>
>
>> From: Paul Roark
> <roark.paul at gmail.com>
>> Reply-To: Leica Users Group <lug at leica-users.org>
>>
> Date: Sun, 15 Jan 2012 08:31:07 -0800
>> To: Leica Users Group
> <lug at leica-users.org>
>> Subject: Re: [Leica] Zeiss ZM 21 & CornerFix
>>
>>>>
> LR apparently has a built in vignetting fixer in its later versions.
> ?Does
>>>> LR now negate the use of Cornerfix?
>
>
> It's possible that
> CornerFix is
>>>> superior to even Leica's lens-coding
> profiles. ?It is
> custom for each lens
>>>> and body. ?You could even make
> it custom for each
> aperture if you wanted.
>>>> Canned profiles may be
> less accurate for your
> particular setup.
>
> Actually,
>>>> the issue with the 21mm Biogon is that
> it's a symmetrical
> design -- said to
>>>> be terrible with the M9, with a
> nodal point that is
> way too close to the
>>>> sensor. ?But symmetrical
> designs are, in my view,
> superior in terms of
>>>> sharpness and distortion
> to retro-focus. ?The 21
> Biogon is really sharp,
>>>> with no distortion. ?
> My 18mm Distagon, said
> by some reviewers to be the
>>>> best 18, is good,
> but not up to the
> Biogon. ?For making large prints, I was
>>>> a bit
> disappointed in the 18,
> thus the 21 Biogon experiment, which luckily
>>>>
> worked. ?But for
> ColorFix, I probably would have returned the Biogon as
>>>>
> unusable with
> the
>>>> M9.
>
> Paul
> www.PaulRoark.com
>
>
> _______________________________________________
>>>>
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>
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>>>>
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>
>
>
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