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

----- Original Message ----- 
From: "John Black" <jblack@xxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Monday, September 27, 2004 11:33 AM
Subject: [pure-silver] Re: old Leica and fast shutter speeds


>
>
>
>> I have an old Leica rangefinder camera from the thirties. 
>> The other
>> day I took it to the beach and shot a roll of film at 
>> 1/1000 of a
>> second, because there was so much light.  But, most of 
>> the frames are
>> only partially exposed on one side.  Can I conclude that 
>> the shutter
>> just doesn't work at that speed?  It seems to work fine 
>> at the more
>> usual speeds of 1/60th, 1/100th, etc. I wonder if this is 
>> a common
>> problem for old cameras.
>>
>
>
> A very common problem with older LTM cameras used at 
> 1/1000 sec is the
> curtain either closing too early in it's travel. Remember, 
> the slit (delay
> until the 2nd curtain releases) is VERY small at 1/1000 
> sec and it requires
> a very well cleaned and adjusted shutter to work 
> consistantly at this speed.
>
> Has it had a CLA recently?  Might be time.
>
> BTW, it is better to use a tighter aperture setting than 
> count on the
> highest shutter speed on these guys.  What film?
>
> JB
>
>
   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 earlier one had journal bearings and relies on the 
residual friction to avoid errors due to acceleration of the 
curtains during travel. The later design uses ball bearings 
in the shutter and has an adjustable brake on the closing 
curtain. This shutter is quite uniform even at 1/1000 sec. I 
don't remember the exact dates of manufacture but think the 
change happened in the mid to late 1930's.
  BTW, while the Leica gives the impression of delicacy it 
is actually a very rugged bit of machinery.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx




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