Archived posting to the Leica Users Group, 2003/05/18

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Subject: Re: [Leica] Vignetting of Summicron M 2/28mm ASPH
From: "Y. Li" <liyue@netvigator.com>
Date: Mon, 19 May 2003 09:58:35 +0800
References: <03E63C98-8802-11D7-A816-0050E42E6E0B@shaw.ca> <001101c31c26$03b78680$0100a8c0@liyue> <00ad01c31c38$3968ed70$70a72350@home> <003101c31c6e$37cd7d60$6401a8c0@oemcomputer> <006101c31c7a$166f8120$6400a8c0@mtwk.sps.mot.com> <001101c31cca$50826440$6401a8c0@oemcomputer> <p0510036dbaec76dddee0@[204.174.36.233]> <005201c31cd0$65cb3f60$6401a8c0@oemcomputer> <p0510036ebaec90f505c5@[204.174.36.233]> <3EC72FB1.C7913BD0@transbay.net> <008501c31d76$10b13060$0100a8c0@liyue> <3EC82D2E.C50410F9@earthlink.net>

The lens was purchased in Hong Kong.
Y. Li

- ----- Original Message -----
From: "Slobodan Dimitrov" <sld@earthlink.net>
To: <leica-users@mejac.palo-alto.ca.us>
Sent: Monday, May 19, 2003 9:02 AM
Subject: Re: [Leica] Vignetting of Summicron M 2/28mm ASPH


> Was this an international or a Leica USA purchase?
> Slobodan Dimitrov
>
> "Y. Li" wrote:
> >
> > Hi everybody on this issue.
> >
> > Firstly, I wold like to thank all of you very much for the discussion
and
> > advice. These are great.
> >
> > Sorry for not replying to your mails on time, in the meantime I shot
some
> > photos to show the vignetting/falloff. The pics are in a folder at:
> >
> > http://www.photo.net/photodb/folder.tcl?folder_id=306074
> >
> > Would you please look at the photos and comment.
> >
> > At the end of the folder there are two photos from my Pentax Optio S
digital
> > to show the reference. There is a tree branch on the right top corner on
the
> > ones with cloudy sky, so don't bother about it. One of the photo, the
"Sky
> > with moon at f2, 1/1000, does show more falloff at the left side/edge.
Is it
> > the shutter as someone mentioned in the discussion? But I didn't realize
any
> > vignetting/falloff with my Summicron-M 2/90 ASPH.
> >
> > The vignetting seems to be stronger with blue object. Is it the nature?
> >
> > I feel the vignetting is far too strong. Or it is normal for the lens?
> >
> > Should I shoot some thing else to verify the vignetting?
> >
> > Thanks.
> >
> > Y. Li
> >
> > ----- Original Message -----
> > From: "tripspud" <tripspud@transbay.net>
> > To: <leica-users@mejac.palo-alto.ca.us>
> > Sent: Sunday, May 18, 2003 3:01 PM
> > Subject: Re: [Leica] Vignetting of Summicron M 2/28mm ASPH
> >
> > > Hi Henning,
> > >
> > >      Look at any interior design magazine or architecture.  The best
> > > shots are large format.  Now digital too.  For large format black
> > > and white prints you can pas on the center filter and adjust in
> > > the darkroom.  I had a 121 SA w/cf, but never really got a
> > > chance to use it without a studio setup.  Big flash is what
> > > it takes to allow for the decreased f/stops with the center
> > > filter.  There's a great book out called The Photographer's
> > > Assistant' which shows what a current studio is like.
> > >
> > > Cheers,
> > >
> > >
> > >
> > > Henning Wulff wrote:
> > >
> > > > At 7:59 PM -0400 5/17/03, Don Dory wrote:
> > > > >Henning,
> > > > >I was mostly thinking of one of the aspheric elements forward or
> > backward in
> > > > >space.  Perhaps I am naive, but I think up to two stops vignetting
in
> > the
> > > > >corners doesn't bother most people.  What was described was a
severe
> > hot
> > > > >spot in the center of the image.  I don't think that even an
unpainted
> > > > >portion of the lens barrel could cause a hot spot in the center;
such a
> > hot
> > > > >spot would move around the frame depending on where the source of
light
> > was
> > > > >coming from.
> > > > >
> > > > >One of my underlying assumptions in this whole discussion was that
the
> > > > >original complaint was a real visible problem.  Over the years, I
have
> > > > >gradually realized that there is usually some basis of fact to
reported
> > > > >problems.  There is, of course, the occasional troll that throws
> > gasoline on
> > > > >a lighted match.  That is usually pretty rare.
> > > > >
> > > > >Don
> > > > >dorysrus@mindspring.com
> > > >
> > > > Don,
> > > >
> > > > The displacement of any element in _any_ direction will first be
> > > > noticed in a loss of resolution and an increase in aberrations. If
> > > > the displacement is axial, the effect will of course be symmetrical
> > > > while radial displacement will produce non-symmetrical
deterioration.
> > > > Either type of displacement will produce very severe degradation
well
> > > > before the slightest effect of increased vignetting is seen.
> > > >
> > > > I don't think the post was a troll; rather a misunderstanding of the
> > > > design aim point and the resultant performance parameters.
> > > >
> > > > I have noticed before that people coming from SLR's have different
> > > > expectations of optical performance than those used to RF cameras,
> > > > just as many cannot get used to the coincidence type rangefinders
> > > > coming from AF SLR's. It can be difficult getting used to the
> > > > different handling, just as the performance parameters of lenses of
> > > > different construction can seem weird.
> > > >
> > > > My 21/2.8 ASPH, while having less vignetting (talking about optical
> > > > vignetting due to lens design rather than physical vignetting due to
> > > > mount or element diameter limitations) than the SA 21/3.4, still has
> > > > more light falloff than any recent good Nikon, Canon or whatever
> > > > 20/2.8. It is noticeable if you look for it, or if you are sensitive
> > > > to it. Conversely, in all other respects it is a far superior lens
> > > > then those same Nikon, Canon or whatever.
> > > >
> > > > The 21/2.8 ASPH is a very mild retrofocus design, constructed that
> > > > way so that metering is possible with the M5,6,7 cameras. This helps
> > > > the vignetting over that of the 21/3.4, but the strongly retrofocus
> > > > 20/2.8 lenses for SLR's are better. There are a few tricks that are
> > > > used to expand the exit pupil size at larger angles so that light
> > > > falloff is less than demanded by cos^4, but at the present stage of
> > > > development, to maintain the best overall performance within a given
> > > > degree of retrofocus ratio will mean that there is more falloff with
> > > > RF wideangle lenses than SLR lenses.
> > > >
> > > > The highest level of performance can still be achieved by using a
> > > > nearly symmetrical construction, and letting light falloff be as it
> > > > may. To compensate for this, a center filter is then used. This
cures
> > > > all the problems except price, size and lens speed. Performance will
> > > > be stellar, as exhibited by modern LF designs.
> > > >
> > > > You can't have it all.
> > > >
> > > > --
> > > >     *            Henning J. Wulff
> > > >    /|\      Wulff Photography & Design
> > > >   /###\   mailto:henningw@archiphoto.com
> > > >   |[ ]|     http://www.archiphoto.com
> > > > --
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> > >
> > > --
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> > >
> >
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In reply to: Message from John Collier <jbcollier@shaw.ca> (Re: [Leica] Vignetting of Summicron M 2/28mm ASPH)
Message from "Y. Li" <liyue@netvigator.com> (Re: [Leica] Vignetting of Summicron M 2/28mm ASPH)
Message from "Rafael Alday" <rafaelalday@yahoo.es> (Re: [Leica] Vignetting of Summicron M 2/28mm ASPH)
Message from "Don Dory" <dorysrus@mindspring.com> (Re: [Leica] Vignetting of Summicron M 2/28mm ASPH)
Message from "Phong" <phong@doan-ltd.com> (Re: [Leica] Vignetting of Summicron M 2/28mm ASPH)
Message from "Don Dory" <dorysrus@mindspring.com> (Re: [Leica] Vignetting of Summicron M 2/28mm ASPH)
Message from Henning Wulff <henningw@archiphoto.com> (Re: [Leica] Vignetting of Summicron M 2/28mm ASPH)
Message from "Don Dory" <dorysrus@mindspring.com> (Re: [Leica] Vignetting of Summicron M 2/28mm ASPH)
Message from Henning Wulff <henningw@archiphoto.com> (Re: [Leica] Vignetting of Summicron M 2/28mm ASPH)
Message from tripspud <tripspud@transbay.net> (Re: [Leica] Vignetting of Summicron M 2/28mm ASPH)
Message from "Y. Li" <liyue@netvigator.com> (Re: [Leica] Vignetting of Summicron M 2/28mm ASPH)
Message from Slobodan Dimitrov <sld@earthlink.net> (Re: [Leica] Vignetting of Summicron M 2/28mm ASPH)