Archived posting to the Leica Users Group, 1998/12/03

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Subject: Re: [Leica] M6 rangefinder accuracy limit & 90/f2 ASHP
From: Nathan Wajsman <nathan.wajsman@euronet.be>
Date: Fri, 04 Dec 1998 07:35:30 +0100

Jorge,

Yes, the table is indeed from Erwin. I do not think that you should be scared
off buying a lens you want by it. To me, it just highlights the need to focus
extra carefully with the longer lenses at full aperture and/or to get an M3 to
supplement the M6, which is what I have done. I have the new 135mm 3.4 lens, and
according to the table it stretches the capability of both the M3 and M6
significantly. Yet it is a great lens, and I know that Erwin also really likes
it, as he has stated several times.

So if you need the extra stop on the 90mm, by all means go for the new 2/90mm.
Just focus carefully!

Nathan

jsaravia@zeus.uniandes.edu.co wrote:

> Hi Lugers:
>
> I have this table from an old mail, not sure about who post it... It was you
> Erwin ????, sorry if  I am wrong.
> -----------
>
> There is a mechanical/optical relationship between the accuracy of the
> rangefinder and the baselength in relation to the maximum aperture/.
> The equation will be published elsewhere, but here is the result:
>
> Focal length    Max aperture    Max aperture
>                 M3              M2, M4, M5, M6
> 21 mm           0.12            0.15
> 28 mm           0.21            0.26
> 35 mm           0.33            0.41
> 50 mm           0.67            0.84
> 75 mm           1.5             1.88
> 90 mm           2.17            2.71
> 135 mm          4.88            6.1
>
> ----------
>
> According with that,  the new 90/f2.0 could reach all its preformance (hard
> to focus ok) when used on a 0,75 M6, or even a M6 0,85 (what about the new
> 135mm/3.4),  I have read that even the 75 f/1.4 is hard to focus.
>
> I use my Noctilux alot and have never had problems with it, I have the
> 80/1.4 and like it very much, I am thinking seriously about the 90/2.0 ASHP
> (I may trade the 80/1.4) but, if when used at f/2.0 it is beyond the M6
> rangefinder accuracy limit, is it worth buying it ? , should I go for the
> elmarit ?...... I am confused....
>
> Any Comments????
>
> Thanks in advance
>
> Jorge Saravia



- --
Nathan Wajsman
Overijse, Belgium

Photography page:  http://members.tripod.com/~belgiangator/index.html
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