Shutter testing a Leica IIF: think this would work?

[Benjamin Marks]

I have a Calumet shutter tester which is essentially a photo-sensor seated in a Bakelite housing. 9v battery and IC board on the inside. Ordinarily you put the photo-sensor end of the Bakelite box against the back of your shutter and a light source on the other side of the shutter and test away. It is a nifty device and works as well with between-the-lens shutters of LF or MF lenses as it does with focal plane shutters of 35mm cameras.

But what to do with a Leica IIIf? As the "back" of the shutter is not accessible without camera disassembly, use of this shutter tester poses a problem.

How about the following?

Slip a sheet of mylar large enough to cover the film gate into the IIIf and test the shutter from the front? I was thinking of positioning the shutter tester and light source at 45-degrees to the film plane.

Any reaction from you learned folks? A quick search revealed speculation about a sound-based solution. I am thinking about something simpler. What do you all think?

Ben Marks

 

[Dwig]

... Slip a sheet of mylar large enough to cover the film gate into the IIIf and test the shutter from the front? I was thinking of positioning the shutter tester and light source at 45-degrees to the film plane. ...

Sounds very workable, assuming the mylar is silvered of course.

I would recommend that you consider a small focused light source (e.g. flashlight) that can be placed closer to the sensor on the tester reducing the angle between the two. Also the line between light source and sensor should be 90 degrees to the direction of shutter travel.

The reasoning for both of these recommendations, particularly the last one, is that the shutter is not in the same plane as the film (mylar mirror in this case). If the light-mirror-sensor light path is parallel to the shutter travel direction, the results will be in error, showing a higher shutter speed than actual. The error will only be noticable at the higher speeds. This is because the sensor won't see light until the opening curtain reveals it to the sensor even though it revealed the light to the mirror earlier, assuming the light is to the side of the curtain supply drum. The sensor will then stop seeing light when the second curtain starts blocking the light striking the mirror, earlier than when that curtain gets to the point that it would block the sensor's view of the light reflecting from the mirror.

Arranging things so that the angle between the sensor and the light is as small as possible and seeing that the line between them is parallel to the edge of the shutter curtain and perpendicular to the direction of travel will eliminate this issue.

 

[Benjamin Marks]

Thanks, Dwig. Your post mirrors (no pun intended) my assumptions. The problem, ironically, may be that the Calumet shutter tester (why do I keep hitting the "i" instead of the "u"?) seats its light sensor in the middle of the small end of a Bakelite brick about 1.5 x 3 inches in size. With the size of the IIIf's shutter gate and the necessity of getting a flashlight in there too, there may be some serious restrictions on how close you can get to the camera. I will try it out this weekend, if I can put my hands on some silvered mylar.

Ben Marks

 

[xayraa33]

Slip out the IIf from its body shell, it is not that difficult.

 

[Dwig]

...there may be some serious restrictions on how close you can get to the camera. ...

I don't think its particularily necessary that the tester & flash light be all that close to the body. I issues of being "close" that I brought up was that they need to be close to each other so that two light paths, light to mirror and mirror to tester sensor, be as close to parallel as practical. Actually, the further they are from the body the narrower the angle between them.

 

[Frontman]

Slip out the IIf from its body shell, it is not that difficult.

I second this recommendation. I set my shutter speeds using the CRT method (television screen) which is accurate and free. I've used this method with several different cameras, and it works perfectly. The CRT method allows a good degree of fine-tuning, allowing me to use the lightest amount of tension to get accurate speeds, which makes winding easier, and which also makes the shutter more quiet. I also get to watch my favorite tv program while working on my camera 😉

 

[John Shriver]

CRT televisions are getting right rare. Only one left here is my restored 1957 Hotpoint 14" portable. I watched the end of analog TV on it. Everything else is LCD.

I use a storage oscilloscope and photocell combination for shutter speed testing. However, the CRT method is good for looking at what each shutter curtain is doing. But I've scrapped the primary CRT television since the last shutter overhaul...

 

[_goodtimez]

I use the CRT method complemented wit the Digital Camera Method.
You may take a look at my replies for the M3 SHUTTER DRAG post a few weeks ago.

 

[ferider]

Slip out the IIf from its body shell, it is not that difficult.

I third this one. It's real easy.

But the 45 degree front testing sounds good too. Also, you can glue aluminum foil on film.

Roland.