Re: [Rollei] Synchro Compur new and old

[Richard Knoppow <dickburk >]

At 12:43 PM 05/04/2002 -0400, you wrote:
>I was speaking to Bill Maxwell the other day, and he said he hates working
>on the 2.8C, because it has a more primitive shutter than the newer models.
>Okay, here's my question:  when did they switch over to the new shutter?  I
>remember being told that the shutter which has tension between 1/250 and
>1/500 is an older variety -- is this what he's referring to?  He said the
>older shutters are less likely to seize up, but harder to adjust for
>accuracy.
>
>(By the way, Bill's a huge fan of the Xenar -- thinks it comes close to the
>Xenotar and Planar.  He doesn't think much of the Tessar, and thinks the 3.5
>Xenotar is the best of the bunch.)
> 
>
>Douglas Cooper
>http://www.dysmedia.com
>
>NO ARCHIVE
>
 I believe the grooved bolster was available by changing the back. I
suspect that new backs didn't cost any more than having the camera serviced
and the bolster replaced. 
 The "new" type Synchro-Compur has an EV scale. It varies from the older
one in several ways. 
First, it has a single drive spring, which is easily replaceable,
practically a drop-in. 
It also has a different drive arrangement for the diaphragm so that the
f/stops are linearly spaced on the scale (needed for the EV system). It
also has different shutter speeds than the earlier versions. 
  The speeds of the later shutter can be changed at will regardless of
whether its cocked or not. 
  I am not sure this type of shutter is any more accurate than the earlier
one. In both shutters the only speed adjustment is by setting the position
of the slow speed gear train. Compur instructions say to set it for 1/10th
second. Other speeds are controlled by the speed cam. While its possible to
adjust a speed cam I think its probably asking for trouble to do it. 
  There have been several Compur shutter models. The earliest are the "dial
set" type, sometimes also called Model A shutters. These have a small dial
at the top of the shutter for setting speeds. They can be made to be
accurate but often the cams are worn. Speeds are limited to around 1/200th
although some small ones are marked higher. This type originated around 1912.
  The second type of Compur is the "rim set", sometimes called the Model B.
Speeds are set by a ring around the body of the shutter. Earlier versions
have speeds to 1/200th or 1/250th and no booster spring. The larger ones
may have a booster spring for 1/200th. Smaller sizes to to 1/400th.  This
shutter appeared about 1930.
  This was followed by the Compur-Rapid, which is similar but has a top
speed of 1/500th.
  Following WW-2 another model with built-in flash synch was made under the
name Synchro-Compur. This is the shutter found on the MX Rollei. 
  Rolleis with EV dials have the later single spring shutter. My
understanding is that this shutter is a variation of the shutter designed
for Hasselblad but without the automatic diaphragm arrangement.
  The dial set Compurs used spiral clock motor type springs. Rim set
Compurs use mostly helical type springs. The late Compur went back to the
clock motor type spring.
  Early dial and rim set Compurs have the sometimes useful ability to open
the shutter in T and B without cocking it. 
- ----
Richard Knoppow
Los Angeles, CA, USA
dickburk  

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