[LargeFormat] xenar question

[Richard Knoppow]

-------Original Message-------
From: animal <s.jessurun95@chello.nl>
Sent: 08/20/03 03:46 AM
To: largeformat@f32.net
Subject: [LargeFormat] xenar question

> 
> Hello today a lens arrived i bought on an auction.
It is a schneider kreuznach xenar 4.5/300
Numbered 295271.
I do not understand the shutter it is in.
It has a small rotary dial on it,s rim a lever marked m b z
Anyone able to help me out?
Thanks
simon jessurun
amsterdam

   This is probably a Compound shutter. If so it will have a cylinder at the top above the speed dial. These shutters were made for some seventy years. The cylider is an air-brake used to regulate the speed. The small dial sets the speeds. 
   The small dial marked M-B-Z is for instantaneous, bulb or time exposures. The shutter does not need to be cocked and, in fact, can't be cocked in B or Z which are bulb and time. You just press the shutter release lever to open the shutter. 
  For M (Marked speeds) the shutter must be cocked. The cocking lever is on the right side of the lens, opposite the M-B-Z dial. 
  The speed dial has some resistance so that it doesn't move when set. The resistance is caused by a spring washer under the center screw. 
  Compound shutters are quite reliable and repeatable when clean. 
  There is an internal adjustment to set the slow speeds. 
  Be careful because the shutter and diaphragm blades of early Compound shutters are made of a fiber composition material. 
   My reason for thinking this is a Compound rather than a dial set Compur is the size. Compound shutters were made up to very large sizes. An early dial set Compur shutter looks similar but doesn't have the air cylinder on it. 
  I don't remember the date of origination of the Compound but I think it was around 1905. They were made until the mid 1970s. 
  Schneider of America has a serial number chart on its web page which will allow you to date any Schneider lens ever made. http://www.schneideroptics.com



Richard Knoppow
dickburk@ix.netcom.com
Los Angeles, CA, USA