[Leica] Testing & manufacturing techniques at Solms

["Doug Richardson" <doug@meditor.demon.co.uk>]

Jim Brick <jim@brick.org> replied re Leica 100% testing

>Yes, I know. But testing each item, and "exhaustively" testing each
item,
is two different things. If each item were exhaustively tested, we
would
have "no" DOA's, scratched film, RF mis-alignment, etc, etc, etc.

I must say the level of testing I saw at Solms looked very thorough.
When Leica says tested they mean TESTED!

One test gadget consists of a turntable on which a lens can be mounted
facing upwards, but with a slight off-axis tilt. A narrow beam of
light (laser I think) is projected down into the lens, and the latter
is turned. This process is intended to detect if any of the elements
is incorrectly centred.

Sadly, no inspection, no matter how careful, is likely to have
prevented the problems I'm having with my 12 year old M6. All were
what I'd classify as premature deterioration due to poor worksmanship
or materials in a camera which had seen little or no use until I
bought it.

I have never had a problem with a pre-1974 Leica camera or lens which
could not be ascribed to the fair wear and tear clocked up in quarter
of a century or more of use (e.g crumbling vulcanite or inoperative
slow speeds).  However, of the ten post-1974 items I own, four have
failed in use, while a fifth proved dead-on-arrival when unpacked by
the dealer. Much through I'm attracted by the new Tri-Elmar, that 50%
failure rate of post-1974 equipment makes me very reluctant to buy
one.

On a happier note, one thing I learned at Solms which came as a
surprise was that the traditional method of grinding lenses in which
several blanks are mounted on a hemispherical surface and ground by a
single tool is no longer used. Machinery of this type had been used at
Wetzlar and re-installed at Solms, but the Leica company soon found
that this time-honoured technique was not good enough for the latest
generation of lenses. Now the individual glass elements are moulded to
approximate shape at the glass works, then individually ground at
Solms on a computer-controlled machine. Each surface takes around 20 -
40 seconds to grind.

Regards,

Doug Richardson