Factory Testing Leica Shutters

I'm not sure if this info has already been posted.

<br>I'll leave it up to the moderator to pull the thread if it has.

<br>This is a brief description of the

<br>machine used by Leitz to check their shutters back in 1946.

<br>From the British Intelligence survey of the Leitz factory in

1946.

<p><i><b> The timing of the fast range of the shutter is carried

<br>out with the aid of a stroboscope of somewhat antique design.

<br>By means of this the 1/200, 1/500 and the 1/1000 speeds are

<br>checked. The stroboscope consists of a revolving drum placed

<br>horizontally, with 33 horizontal slits in its surface,

<br>illuminated from inside by a lamp of approximately 20 watts.

<br>The drum is driven by a belt from an electric motor which may

<br>be controlled by a rheostat. The drum is also coupled to a

<br>speedometer in order that its speed may be set. The correct

<br>speed for the drum to rotate at was 280 r.p.m. The camera

<br>is held on a wooden block in such a manner that the light

<br>from the rotating drum falls on the blinds of the focalplane

<br>shutter. The shutter is then fired and a series of

<br>stroboscopic lines are seen in the aperture. If the shutter

<br>is correctly set these lines appear vertically but if the

<br>shutter is incorrectly set the lines will curl down either to

<br>the left or to the right according to whether the shutter is set

<br>too slow or too fast.

<br>The checking of the lower speeds was only carried out

<br>on the 1/20 second and 1/4 second settings by means of a

<br>revolving series of lights. The various speeds of the shutter

<br>were not accurate to the measurements on the shutter control

<br>knob and this fact was acknowledged by the Leitz executives.

<br>who pointed out, however, that the results obtained were quite

<br>good enough for all general requirements.

<br>A metronome was used in checking the one second

<br>escapement.</i></b>

I hope that it is more accurate now!

More proof of my often repeated statement, "Photography is not an exact science."

The British were very impressed by the sophisticated milling machine used to cut the focusing helixes, but were absolutely amazed when they they came upon this contraption.

<p>Steve Grimes has a description of such a system, with pictures, on <a href="http://www.skgrimes.com/idcc/index.htm">his site</a>.</p>

Did you get that from Peter Grisaffi's site (http://www.crrluton.co.uk)?

J.-C.,

 

>>Steve Grimes has a description of such a system,<<

 

sad news : I just read on another forum that Steve Grimes died yesterday.

 

Carsten

 

http://www.cabophoto.com/

The full Intelligence Report is here

 

http://www.angelfire.com/biz/Leica/page26.html

Thank you very much for sharing this interesting report.

 

Let's do everything possible to preserve the history of Leitz and Leica, while it is still possible to find the materials.

 

Does anyone on this learned Forum know whether Leitz' patents were actually confiscated after the second world war, and whether they were sold to or in other ways made available to Kodak, Nikon, Canon, or other then existing or later founded manufacturers of cameras and lenses?

 

In other words: Do the 35 mm Nikons etc. basically build upon the technology developped by Leitz?

The old crochety German I worked with for a coupla years

had (as I do) and old analog "shutter" tester. (Bowens).

before this, he set the slow speeds "by ear" and the high

speeds by looking at flourescent lights....

R.E. "exact science!!??"...he CLAIMED to have never had a

'photographic' complaint....I've also seen folks (in an otherwise

operational camera) use this approach:

Set the second curtain tension to get 1 sec-1/8 "sounding"

right...then, slow down the first curtain until it starts

to "wedge"...then crank it up a little bit until it looks

"even"....then, narrow the slit width till it "clips", and

then BACK it off till even...!!!!!...with NO instruments...

(I've done this in another town with tools but no test

equipment--I guess it was close enough!???)

I'm sure this results in a "random" 1/1000, but sure is

close enough on the rest for any normal photo use.....

 

The shop I worked at had a nice Copal unit that measured

both travel times, as well as the actual exposure at three

points across the film gate....but I'm not sure that those

cameras "worked" any better than the "drum" or "light bulb"

tests that the old German used....hell, why argue with

decently exposed Kodachromes?

 

Walt

An interesting offshoot of this report and the rest of the British investigations of Leitz, was the Reid & Sigrist camera which was an improved copy of the Leica IIIc. Ivor Matanle, in his book on collecting classic cameras suggests that the Reid was better built than the original and had a better standard lens. I remember seeing adverts for these cameras in the mid 'sixties when the stock was being sold off 'cheap' by Marston and Heard in London. At that time they were going for £39 which was a lot but a very small part of a Leica's price. Now, you'd be lucky to find one for £500.

Thanks Charles, that's a very interesting read. I feel sure the

shutters were plenty accurate for B&W print work. Indeed they

still are today. What, with metering vagaries, film choice,

exposure latitude, developer dilution, develpment time, agitation,

printing time and contrast control, the exact shutter speed is but

one variable among many. IMHO, consistency is more important

than accuracy. With more than one M in your stable, they both

need to be sort of close to one another, but still exact accuracy is

not that important.

 

It would be fun to build that contraption and test my M6TTL (or

soon to be MP;-)

You can get a rough check of the 1/60 speed by photographing a TV screen. The TV station transmits 60 fields per second. With interlaced scanning, that's equivalent to 30 frames per second. If you photograph the screen at 1/60 and part of the TV picture is dark in your print, your shutter is set faster than 1/60. You can tell whether the photo image of the TV picture contains more than 1/60 worth of scanning lines, because you can see the interlaced lines of a partial second field (it's best to have the camera on a tripod and accurately focused, as you'll need good resolution). If you see some interlaced lines in addition to the lines of a single field, your shutter speed is slower than 1/60. This applies to TV systems using the NTSC system, as in the U.S.

 

In England, they use 25 frames per second, and 50 fields per second. Therefore the check can be done at the 1/50 second shutter second. With either system you may see the synchronization pulse, visible as a bar in the picture, but that won't hurt anything.

 

I suppose if you open the camera back and just look through the shutter, you could do this without film; but you'd have to look fast!

When I first moved from AF SLR's with their ultra accurate shutters to my M6 I was worried that shooting tranny would be a bit of a hit and miss affair - wrong - I get consistently better results. Also worth noting is that the M6/7 uses stopped down metering - it measures the light falling on the film plane at the actual taking aperture - SLR's with their full aperture metering will always be at a disadvantage as the aperture is never 100% right - my old canon FD lenses were notorious for havig different exposures for the same aperture on different lenses.