[rollei_list] Re: OT: Leica vs. Zeiss

You have tried this lens on an R System?

On Tue, Nov 17, 2009 at 9:54 PM, Frank Dernie
<Frank.Dernie@xxxxxxxxxxxxxx>wrote:

> Actually Apo is a typo in the case of this lens as such an item does not
> exist. The latest 50mm f1.4 is Aspherical not apo. It is by a long way the
> best f1.4 lens I have used wide open, and I have used a few. The new-Zeiss
> 50 f1.5 sonnar is reported to be a retro lens and is soft and suitable for
> portraits wide open, though I have not used one personally. Only 2 Leica M
> lenses are marked Apo, the latest 90mm f2 and 135mm f3.4. I would be
> prepared to bet five bob that they really are apo...
> The Leica lenses I have, which is quite a few, may not all be apo, whether
> marked thus or not, but they show noticeably less chromatic fringing than
> most of the fast lenses I have from Nikon or Canon. FWIW.
> Frank
>
> On 17 Nov, 2009, at 23:15, Richard Knoppow wrote:
>
> >
> > ----- Original Message ----- From: "Jan Decher" <Jan.Decher@xxxxxxx>
> > To: <rollei_list@xxxxxxxxxxxxx>
> > Sent: Tuesday, November 17, 2009 8:53 AM
> > Subject: [rollei_list] Re: OT: Leica vs. Zeiss
> >
> >
> >> Marc,
> >>
> >> This is what I thought.  So we should compare a current Summicron to
>  the curretn Zeiss ZM Planar perhaps (tie?) and the Apo-Summilux to  the new
> 1.5/50 Sonnar (Summilux wins, I suppose).
> >>
> >> I might take you up on stopping by at your house next time I am in  the
> D.C.  area (X-mas?).  Aren't you down there somewhere (Virginia?).
> >>
> >> Really ought to see that PLOOT reflex housing ;-)
> >> ...and maybe you even have an original Contax OIympia Sonnar engraved
>  by Leni Riefenstahl....
> >>
> >> Jan
> >
> >    I wonder if the Apo-Summilux is really an apochromatic lens. The
> prefix Apo has been used on a number of German-made lenses which are, in
> fact, just plain achromats. For a while there was something in the DIN
> standards that allowed this despite the very long use of the appellation
> apochromatic to mean a lens with longitudinal chromatic correction for three
> colors and correction for spherical aberration for two colors. The chromatic
> aberration curves for apochromatic lenses has a characteristic S shape and
> crosses the zero line (no chromatic error) in three places. An acromatic
> lens is corrected for two colors for focus and one color for spherical. In
> fact, a well designed achromat may have less deviation from focus at
> intermediate colors than a poor apochromatic lens but, in the past, most
> true apo's have been designed for special purposes, such as process work,
> where it was imperative that chromatic correction be very good.
> >    I don't think the term "apochromatic" has ever been officially defined
> for camera lenses but it has for microscope and telescope objectives so the
> term is very well established.
> >    It is possible to correct a lens for any number of wavelengths. Those
> corrected for more than three are known as superachromats. They are rare
> because they are quite expensive to make and have little advantage as
> general purpose camera lenses. Nonetheless they do exist for special
> purposes.
> >    Simply being apochromatically corrected is no guarantee of lens
> performance, there are still many other aberrations that must be well
> corrected.
> >    As I stated before the only way to make definite comparisons of lenses
> is to set them up on an optical bench and see what they do. If the actual
> prescription is available one can set up the design in a computer lens
> design program and analyse it. Modern programs can completely characterize a
> lens in a few seconds, an analysis way beyond what could be accomplised with
> hand or calculator assisted math in the past. Of course, the design
> performance may not be realized in an actual production lens.
> >
> > --
> > Richard Knoppow
> > Los Angeles, CA, USA
> > dickburk@xxxxxxxxxxxxx
> > ---
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-- 
Peter K
Ó¿Õ¬

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