Archived posting to the Leica Users Group, 2000/01/20

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Subject: Re: [Leica] Bessa R & lenses & Lens Testing
From: Stephen Gandy <leicanikon@earthlink.net>
Date: Thu, 20 Jan 2000 10:21:43 -0800

The difference in lens tests does not surprise me one little bit.

Lenses vary right off the assembly line, due to such things as manufacturer's tolerances, unannounced changes in the glass or mount
which may or may not improve image quality, employee error (whether it be a temporary lapse, or a learning curve), and the occasional
defective part (metal or glass) that somehow makes it to the consumer.    Hopefully of course, the higher priced the lens, the tighter
those tolerances are.

The Voigtlander lenses are much lower cost lenses than Leica, it's only reasonable to expect more lens variation.  the different test
reports reflect this.  All reports that I have heard about show excellent Voigtlander  test results, some show extraordinary results.

On the other hand, don't get too wrapped up in the magical reliability of any lens test method, or lens tester.  Regardless of what a
great job they did, they didn't test the lenses they didn't test.  There is an manufacturing tolerance for even Leica lenses. How do we
know where  a tested lens fits into those tolerances ?   At the high end?  in the middle?  or at the low end ?   The ideal testing
situation may be to test a large enough sample lenses to reasonably be sure what the average performance really  is.  I don't put much
trust in a test of ONE lens.   Increase the sample to 25 to 50 lenses in different serial number batches, and I would be inclined to
believe the average results.   Another  lens testing problem is the source of the lenses.  Is the lens a random off the shelf purchase,
or specially selected through the manufacturer and distributor?

Stephen Gandy



Lucien wrote:

> Hans Pahlen wrote:
> >
> > A tip to European LUGers:
> > I just got the latest issue of the German FotoMagazin in my mailbox (February issue).
> > They have a 2 page article with pictures of the Bessa R, and tests of the 25-35-50-75 mm lenses. The lenses got splendid results:
>
> > Heliar 75/2.5  (9.8)
> >
> > For reference, some M-lenses:
>
> > Elmarit 90/2.8  (9.6)
>
> And this is certainly not what Erwin P. and Tom A. wrote
> about the 75/2,5.
>
> Lucien