RE: [Rollei] New member

[Richard Knoppow <dickburk >]

At 11:43 AM 11/14/2001 -0800, you wrote:
>I was just about to ask why I couldn't set the shutter
>speed to 1/500 today when I was sure I did it
>yesterday!
>
>You must be clairvoyant!  How did you do that!
>
>
>--- Siu Fai <siufai   wrote:
>> FWIW, on this model you cannot set the speed to or
>> from 1/500s when the
>> shutter is cocked. So don't try this or you'll break
>> it.
>> 
>> Have fun,
>> 
>> Siu Fai
>> 
>
  In the older Compur shutter the highest speed is obtained by tensioning a
second booster spring. The spring is on the shaft which operates the blade
ring. It always rides the shaft but at all but the top speed the free end
is not held by anything. At the top speed a cam on the speed ring pushes
against the free end partially compressing it. That's the resistance you
feel when setting the shutter to its top speed and reason that the distance
on the speed scale is so long between the penultimate speed and top speed. 
  When the shutter is cocked the shaft turns compressing the booster spring
even more.
  If you try to set the shutter to its top speed when its cocked the cam
must compress the booster spring while its other end is already moved in
the tensioning direction by the shutter mechanism. The result is that the
speed cam must apply a very large amount of pressure against the spring,
which tends to wear both cam and spring surfaces and the end of the spring
may be forced under the cam, which will very effectively jam the shutter.
You can actually move the speed setting to top speed (1/500th on most
Rolleis) but you will find it takes a tremendous amount of force to do it. 
  Setting it to a slower speed while cocked also applies a lot of force to
the sliding surfaces but doesn't have the risk of jamming the shutter. 
  The later Compur is of a different design with a single spring of the
clock motor kind (spiral spring). The spring is always partially wound and
is only give an final winding by cocking the shutter. This kind of shutter
allows free changing of speeds whether cocked or not. One way to tell which
shutter you have is simply to set the shutter to its top speed and see if
there is some resistance. If so, its the older type. E and F Rolleis all
have the later type shutter. I am not sure about late Automats with EVS. I
think the EVS shutters are all of the later type but someone on the list
probably knows for sure. 
- ----
Richard Knoppow
Los Angeles, CA, USA
dickburk  

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