1936 Plaubel Roll-Op Part 2

 I managed to find another day to myself and the last piece for the Roll-Op arrived so now it's finally ready for use. I thought it was going to be ready much earlier until I found out someone had replaced the chain in the rangefinder section with one that was too short meaning it couldn't be adjusted to infinity and it didn't open and close smoothly. Let's dig in!

So, here's the camera with the lens off and a diagram of where the chain would normally go, the toothpick is there to keep the bottom lever in place.:

The spring on the right hand side of the picture is pulling the lever at the bottom up. As the silver section rotates counter-clockwise that lever gets pulled up and the rangefinder adjusts for the chosen focus. We'll go into how the rangefinder works in a bit. Here's a photo of the focus lever and scale:

Here's the new chain in place, it's very fine, 0.5mm in diameter. I had the end of the chain dangling out of the where it screws into for fine adjustment, I'd loose the screw a little, adjust, test the opening and closing action then repeat until everything only just cleared.

I had to do this twice, as the first time I tried to be lazy and just screw the chain down as shown. This just snapped it and it came rocketing out the tiny hole so I did it again and properly. Now, I can not stress how useful toothpicks are to have at all times, I stuck one in this screen hole so I could coil the chain around it and keep it clear.

Now on to the rangefinder. This is an early rangefinder that works by converging the top and bottom of an image together, something like in this photo:

You can see through the sign here that the top and bottom of the pole don't converge. As you change focus they will converge and when they do you can say that that distance is in focus. This works the same way as your eyes do. If you hold a finger directly in front of your right eye it's looking straight ahead while your left eye needs to look towards the right. As you move your finger further away your left eye has to adjust to a shallower and shallower angle to keep that in focus. Here's what that looks like with mirrors in the rangefinder

As I move that silver lever the right hand mirror gets moved forwards and backwards, moving the reflected image from the mirror on the left. Here's a look at the front of the camera and the 2 windows used in the rangefinder

Here's the path the light takes to your eye. The blue path is the top image. It comes over the top of the mirror and into your eye directly. The red path is the bottom image, it comes through the front of the camera, reflects off the mirrors and then enters your eye.

And here's what it looks like through the rangefinder, as you can see the top and bottom image line up so that power pole is in focus.

Now we can get on to adjustment. To adjust the rangefinder we focus the camera to infinity, point it at a sufficiently distant object and turn some screws until we converge the object at infinity. This screw here adjusts the horizontal angle at which the mirror is held, brining the object into and out of convergence.

And this screw here adjusts the vertical angle of the mirror, moving the image up or down in the plane so you can make sure it all lines up vertically as well.

With everything in line and in focus I put a little bit of thread locker on the screws so they don't move, now I want to check that the rangefinder is correct and that the lens is in focus as well. In order to check focus I have this bit of ground glass, which is frosted on one side.

This gives the lens something to throw an image on to, so with a bit of blu-tac we can see what would be projected on the film plane with ease.

With this in place I got out a loupe and adjusted the position of the front element of the lens to bring that distant power pole into sharp focus:

Then I bought the camera inside, focused on a close object and measure the distance to the film plane. If the rangefinder, focus scale and image all align in focus then my jobs done, and luckily nothing needed adjusting. I chose the handles on my closet for this as they're very easy to focus on and have strong vertical lines for the rangefinder.

Lastly the film chamber was pretty beat up, and internal reflections are no good for photography, so these needed a touch up with a bit of enamel paint.

I also did some cosmetic repainting off camera to touch up some numbers and grooves. This is the frame counter and it was pretty beat up, looks great now!

All done! The last thing to do it to shoot a roll of film and see that it's all light tight. I'm out of 120 film at the moment but I've got 20 rolls coming next week so up next will be some photos from this camera. Both of these cameras take the same film, the Plaubel is from 1936 while the Fuji was made up until 2001.