Focus scale calibration (Pentacon Penti I)

[Topy44]

Hello!

My first post to this wonderful board, I have recently started shooting film again and I am currently trying to get to work a nice little point and shoot I got here: An eastern German Pentacon Penti I from 1961.

When I got it the shutter adjustment ring was stuck and there was a lot of gunk inside, so I had to open it and clean it properly. Not a problem, everything works fine now. Unfortunately, by removing the outer adjustment rings, the focus scale no longer matches the lens focus. The outer focus ring (with the scale printed on) has 4 tiny screws that "grab" the "real" focus ring on the lens assembly, and there are no clues to where exactly it was fixed before. So I guess I need to recalibrate it... However I have no idea how to do that. I tried taping an improvised focusing screen to the back and opening the shutter in bulb mode, which gives me a clear picture, however its far too tiny to set focus based on it. Its a half-frame camera, so the frame is just 18x24mm...

What would be the proper procedure to set it up?

If you don't understand what I mean I can try to take a few pictures of the mechanics...

 

[Denverdad]

I think you are on the right track with how you were doing it. You just need a loupe or other magnifyer to view the image on your improvised screen. That is how I have done it anyway, and it has worked well - granted with medium format cameras in my case, so maybe focus is a little more critical with the half-frame format. But one thing I found helpful was to use distant light sources at night (such as street lamps) as my target for setting infinity focus. That way it comes down to just getting a single high-contrast image focused down to as small a spot as possible.

By the way, I had to look up what a Pentacon Penti was. Cute little camera!

 

[Topy44]

Thanks for the "distant light at night" tip, I'll try that!
However as you said, the format is a bit of a problem. Its just really hard to see if a light spot the size of a dust particle is in focus or not, or how its changing size when focusing...

[EDIT]
Just tried it with streetlamps, I can barely see a difference between the two extremes, even with a rather strong loupe. Its just all far too small. I wonder how this was done at the factory...

 

[Denverdad]

Just tried it with streetlamps, I can barely see a difference between the two extremes, even with a rather strong loupe. Its just all far too small. I wonder how this was done at the factory...

Are you doing this with the aperture all the way open? (is it f/3.5 on this camera?) If you have the aperture stopped down the depth of field is too great and things won't change much with focus, so it should be wide open.

 

[aliju]

Hey,
Sorry, I can't help here, but I've got a similar problem... I also have a Penti, and now it looks like the shutter is stuck - When you open the camera, the lens isn't covered by anything, so you can "see right through the lens". Carefully prodding the visible parts of the shutter (these crescent-shaped bits of metal...) didn't help. Do you maybe know how to fix this camera? Sorry if my English sounds strange, I speak German normally. Thanks!
aliju

 

[moki]

You could try taking a series of photos of exactly spaced objects (I use film canisters at 1, 1.25, 1.5, 1.75, 2, 3, 4 and 5 meters)... you simply measure the distance object to film plane exactly and take one photo at each of the according distance settings. In the developed pictures you can see, if the focus is about right (it isn't in your camera, obviously) and which setting is right for which distance. For example: You see that while the setting is at 1m, the can at 1,5m is sharpest - now you know, the difference in focussing and can simply focus to 1,5m if you want to take a photo of something 1m away and simply make a new focussing mark on your camera. I don't know, if the focus can be adjusted on a Penti, so it's probably the easiest way, though you may lose infinty focus that way. If it's not too far off, simply using a slower aperture can help in that case... The 35mm lens has a large DOF and with these slow shutter speeds you're forced to close the aperture anyway for most pictures.

@aliju: My Penti usually needed a little violence when that happened. It seems to be a common problem. Just try to press the shutter again and hit the side (where the transport rod pops out) with your flat hand a few times and see what happens. I wouldn't try that with any more expensive cameras, but with this little piece of faux gold, it's worth a try.