[LargeFormat] Wollensak Rapax Shutter

[Richard Knoppow]

----- Original Message ----- 
From: "Timothy Atherton" <tim at KairosPhoto.com>
To: "Richard Knoppow" <dickburk at ix.netcom.com>; "f32 Large 
Format Photography Mail List" <largeformat at f32.net>
Sent: Friday, November 18, 2005 3:46 PM
Subject: RE: [LargeFormat] Wollensak Rapax Shutter


> Richard,
>
> not specifically related to your post, but have you 
> checked out this
> treasure trove (frequently added to)?
>
> http://www.cameraeccentric.com/html/info.html
>
> Can't recall if I've posted it previously
>
>
> tim a
>
>> -----Original Message-----
>> From: largeformat-bounces at f32.net 
>> [mailto:largeformat-bounces at f32.net]On
>> Behalf Of Richard Knoppow
>> Sent: November 18, 2005 4:17 PM
>> To: f32 Large Format Photography Mail List
>> Subject: [LargeFormat] Wollensak Rapax Shutter
>>
>>
>>   Until the other day I thought the Rapax, also sold as 
>> the
>> Graphex, originated after WW-2. It turns out that it
>> probably was first made about 1942 or 43, not long after 
>> the
>> Kodak Supermatic. The first Rapax/Graphex shutters 
>> evidently
>> had brushed chrome faceplates rather than the black ones
>> familiar to me. Graphex was a trade name used by Folmer
>> Graflex for shutters sold on Speed Graphic cameras. From 
>> the
>> advertising I just noticed the first shutters were the 
>> small
>> sized ones used for 101mm lenses.
>>    I wonder if anyone on this list has one or has seen 
>> one.
>> At the time this shutter first came out Wollensak was 
>> still
>> using Velostigmat as the trade name for its best lenses.
>> Like Ektar, Velostigmat, and the later Raptar, specified 
>> a
>> quality of lens rather than a generic type.
>>    Rapax/Graphex shutters are good ones. Their advantage
>> over the Supermatic and Compur is that the force 
>> necessary
>> to trip the shutter is low and constant at all speeds. 
>> This
>> is important where a solenoid is used for flash
>> synchronization. Both the Supermatic and Compur require
>> rather higher pressure for tripping at the highest speed.
>> Unless booster batteries are used the solenoid may not 
>> trip
>> them at all at this speed. Also, the pressure is great
>> enough even at slower speeds to cause unreliable 
>> operation
>> of the solenoid unless either an extra battery is used or
>> one uses the special higher voltage dry cells sold at the
>> time for photo-flash use.
>>    I am especially curious if anyone has both the
>> Velostigmat and Raptar/Optar versions of the lenses sold 
>> for
>> Speed Graphic use. My experiencew with post war Raptar
>> lenses is that they have a design flaw resulting is 
>> blurry
>> images in the corners and margins even when stopped down 
>> to
>> minimum despite being very sharp in the center. I am
>> wondering if the design of the lens was changed c.1946 or 
>> if
>> the older versions also have this problem.
>>
>> ---
>> Richard Knoppow
>> Los Angeles, CA, USA
>> dickburk at ix.netcom.com
>>
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