[pure-silver] Re: old Leica and fast shutter speeds

> >
> >
>    The curtain tension is constant on the Leica type
> shutter. The slit width is controlled by the delay cam. When
> setting the camera up one sets the curtains with the tension
> specified in the repair manual. The shutter is then tested
> for timing and for uniformity of exposure across the slit.
> Small adjustments are made in the tensions until both are
> correct. Some care is needed in measuring the shutter speed
> because the _effective_ speed of the shutter at higher
> speeds is less than the speed that will be indicated if its
> not illumintated correctly or if the sensor is too large. A
> properly adjusted Leica shutter should be accurate at all
> speeds. Leica had at least two variations of the shutter.


The problem here is a fairly common one called "capping" where, as you say,
the already very small slit effectively "caps" or closes before exiting the
format.  The ball bearing shutters came in durring the war and were more or
less standard by the late 40s and early 50s.  All of the F and G shutters
were ball bearing (I think) and most of the late C models.  The A and B
cameras did not use this technology. I understand that the ball bearing
shutters were developed by Leitz for the military in order to make them more
reliable at the colder temperatures that were being encountered in high
altitude reconisance avaiation and airships.

I have a wartime (1945) IIIc that has bearings but a 1937 IIIb that does
not.  The IIIc has a reliable 1/1000, the IIIb does not.



>   BTW, while the Leica gives the impression of delicacy it
> is actually a very rugged bit of machinery.


Indeed, and the rangefinder is easy to adjust with a small jeweler's
screwdriver but the M cameras are difficult.

JB



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