Re: Advice on RF calibration in SM Leicas?

["C.M. Fortunko" <fortunko@boulder.nist.gov>]

Note Bene Aleksander,

FED stands for Feliks Edmundowicz Dzierzynski(get your spelling right), a
Polish aristocrat an the founder of Cheka, the predecessor of NKVD, and FED
is not a Russian, but Soviet knock-off (don't mix up the two). 

While visiting Russia, I had to explain that I carried a Leica, not a FED.
Most Russians, like most Americans have never seen a real Leeka. In fact, I
have not seen anyone use a SM Leica during the past 25 years.

Regards,

Chris


At 07:31 PM 2/7/97 -0500, you wrote:
>Sirs/Mesdames(NB: are there any here?),
>
>I'm new to LUG (have been lurking for a month) - forgive, if I raise
>topics that
>have already been discussed.
>
>It seems that my grandfather's FED (russian LeicaII knock-off) has
>finally given
>up the ghost and I have to get a real issue. It won't be named after a
>Grand 
>Inquisitor (FED stands for F.E.Dzerzhinski), but I hope it'll be better
>made. 
>Methinks, a postwar IIIc or a IIIf should do. So my first question is:
>
>1. How can one check the RF calibration in a store, where distanses to
>objects are
>not known? I hear that many outfits claim to have cameras adjusted when
>it's not 
>really the case.
>I have an idea. I got a well calibrated lens, Jupiter 85/2 (not at all a
>bad one,
>it's based on Zeiss Sonnar). I mount it and stand in front of a mirror.
>Focus on
>the mirror edge/frame, note the reading, then focus on lens in the
>mirror, again 
>taking the reading (must be X2, of course). Repeating the procedure from
>several
>points should expose any systematic error, since the scale is non-linear
>(parabolic ?). Obvious problem - the mirror curvature and other
>distortions, 
>introduced by it. Will it render the whole rigmarole useless? Any other
>pitfalls?
>Other ideas? 
>
>2. That brings me to another heretical question: is precise focusing
>possible on 
>a Leica? (Please don't unleash an angry fusillade that L is the best;
>this we 
>already knew). L is supposed to be an available light camera with lenses
>that 
>produce good results when wide open. Let's say I'm focusing my 85/2 on
>an object
>2m away. At that distance and aperture 2.0 the depth of field should be
>about
>+/-1cm (I don't remember the formula by heart). I have an excellent
>eyesight
>(used to see all rows in the test table) and I would have a lot of
>trouble
>focusing in an ideal situation. How one can focus on a victim's eyeballs
>and not
>eyelashes in low light with somethinglux 75/1.4 that Leitz makes (even
>less DOF)
>is beyong me.
>But that's not all. What about mechanical reliability of RFs and lens
>mounts? 
>It's hard to imagine that 40 or 60 years of wear and tear would do to
>the
>extremely precise and fragile mechanism of RF, where hundredths of mm
>count.
>
>3.Recently, when I was looking at a IIIf, I noticed that the
>spring-loaded RF
>"arm" (not sure what it's called in English) has a roller disc on its
>end and
>not an eccentric as I would expect. I don't want to spill graphs and
>formulas
>into this letter, so can anybody enlighten me as to where info on RF
>workings
>can be found? I mean math functions that describe all these gearwheels,
>racks 
>and pinions.
>
>BTW, if somebody is selling a good IIIc or IIIf (look is not very
>important),
>let me know. 
>Or, maybe, some can advise on good stores to buy from.
>
>Thanks for your time.
>							Alexander Finkelstein
>
>