Focus problems with a Voigtlaender Rollfilm folder

[ntenny]

Gentle Readers,

I've been lucky enough to score a Voigtlaender Rollfilmkamera (circa 1928) for a song on eBay (the seller thought it was a 620 camera and priced accordingly). Like all the old Voigtlaenders, it's a lovely piece of engineering, but when I put a roll of film through it as a smoke test, the results were complete mush---everything out of focus, even at infinity and even when stopped down, except for an occasional picture (always near-range) where a random portion would suddenly be in focus for no apparent reason.

It looks to me like a problem with the film plane. (If it were my focussing, infinity would be OK; if it were a misaligned focus scale, things would be consistently in focus but at the wrong distance.) The camera has no pressure plate, but looks like it never had one; I found an online manual and it doesn't show a pressure plate or indicate any special treatment when loading.

So I'm a bit at sea here, since I don't see what could be causing the film plane to be misaligned. The lens has been worked on by someone who wasn't especially careful (they left gouges in the paint by the slots on the rear cell); if they reassembled it with an alignment problem, would that explain my results? How do I figure out how to fix it, if that's the case?

Thoughts?

Thanks

-NT

 

[walter23]

Maybe you could try taping some magic tape or other slightly opaque film along the film path inside the back and walking around with the back open using the tape as a ground glass to check focus? I used this method to calibrate focus on my lubitel.

This would confirm or refute your idea that it was a problem with the film flatness. If you can't get good focus with the tape ground-glass in place along the ideal film path, you'll know that at least something else is going on.

 

[ntenny]

Well, I did some fiddling around with a piece of ground glass, and I concluded that this is the weirdest problem I've ever seen in a camera. The issue is that the lens is severely non-parallel to the film plane; and that, in turn, is because when you open the camera, the bed sits at less than a right angle to the body!

All the dimensions seem to be factory-fixed; the angle of the bed depends only on the position of the hinge, the positions of the rivets holding the struts, and the length of the struts themselves, none of which are open to easy change and none of which look like they've ever been messed with.

It's possible to force the bed to overbend a little so that the lens leans a little forward into the correct plane, and if I do that, the focus seems to be spot on. But I can't figure out any way to tinker with the camera to make that a permanent arrangement.

Now that I know to look for it, the misalignment is totally obvious to the naked eye. How on earth did a Voigtlaender camera ever leave the factory in this condition?

I'm trying to figure out a way to salvage it, but this camera may end up being a shelf queen. It is gorgeous, but it's *so* close to being an outstanding user, I hate to give up on it.

-NT

 

[David A. Goldfarb]

With some of these cameras, like my Perkeo II, you have to open the camera, and then gently pull the lens/shutter assembly into position until it clicks into place. Have you tried that?

 

[ntenny]

With some of these cameras, like my Perkeo II, you have to open the camera, and then gently pull the lens/shutter assembly into position until it clicks into place. Have you tried that?

It's not really an option. The Rollfilmkameras aren't self-erecting; they're more like miniaturised field cameras---the "barn door" contains a track along which the front standard slides. Same general mechanism as on the Vag/Avus/Bergheil (or other plate cameras of the era).

As far as I can tell, the only options are to change the angle between the bed and the body, change the angle between the bed and the standard, or change the angle at which the lens sits in the standard. (I thought about tilting the film plane, but I can't see a way to do it---it would require the film to move further back than the back of the camera, for one thing.)

-NT

 

[David A. Goldfarb]

I see. Well it could just be that something's gotten bent in the last 80 years or so.

 

[elekm]

If the camera was dropped, that would knock it out of position. And if had been dropped on a carpeted floor, for example, it wouldn't show any impact damage.