Kalart Rangefinder: Calibrated but not tracking properly

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A couple weeks ago I took delivery of a 4x5 Pacemaker Speed Graphic, and spent two rather frustrating afternoons getting the Kalart Rangefinder calibrated with my 7" Aero Ektar. After a lot of trial and error (plenty of the latter), I got it working properly from about 4'6" to infinity, which I was happy with. It was a little out of horizontal alignment, and I couldn't quite get that long skinny screw to turn enough to get it right. I figured I could live with it, but wanted to see if I could find some more info later and poke around a bit to see if I could get it 100%. Alignment issues aside it's a really nice example, it's not yellowed and dim like many of the other older RF's I've seen.

Anyways, the camera was sitting around on the tripod with the covering of the RF removed, and I accidentally bumped into it. Now the images in the RF do not track except for a little bit at maybe around 7-8' or so. After some investigation, I found that it's actually still in calibration at all distances, but the arm that moves the prism isn't making contact with the angled copper (brass?) piece that moves as the cam does. If I nudge it forward gently with my finger, the images line up properly at all distances.

I'm really hesitant to adjust anything without knowing exactly what I'm doing, as it took me several hours to get the RF set properly for the Aero Ektar and I really, really don't want to repeat the process. Does anyone know what I need to tighten, re-adjust, or open up to set it right? I'm hoping to take it shooting at a local event on Sunday. Here's a picture with a close-up of what I'm talking about.

http://farm5.static.flickr.com/4018/4506214232_7817f6d4bd_o.jpg (http://www.flickr.com/photos/chadcullen/4506214232/?rotated=1&cb=1270842674254)

Thanks!

[Robert Hughes]

Do you have the proper cam for a 7" lens, or are you using the default cam that came with the camera (as would be used with the 127 or 135mm lens)? Each focal length requires its own cam to focus properly through the distance range.

[Frank Petronio]

That kind of RF does not use cams

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Frank is correct, I think it's the Hugo Meyer's that required cams. The Kalart can be reconfigured for a pretty good range of focal lengths, although I think the 7" is pushing the long end of its limits.

I think I've fixed it, there is a wire at the bottom that seems to hold the tension of the prism assembly. It looked to have slipped off to the side, I tried pushing it under the prism and it's now tracking throughout the range. I was just a hair off at infinity before so I reset it today, now everything else is a little off... looks like I'll be spending another quality afternoon with my tripod, loupe, and tiny screwdrivers :p

[Glenn Thoreson]

The little spring wire does indeed have to be in it's proper place. Are you sure you're adjusting the right thing to get horizontal coincidence? It takes very little to do a lot. If you got it to focus down to 4.5 feet, youve done very well, as they weren't designed for use under 6 feet. Have fun.

[JOSEPH ANDERSON]

Having same problem with an old B&J PRESS. I had it just about perfect. But, horizontal
was off just a bit. I should have left it alone. But, of course I didn't. most have touched
or turned something. Now have to calibrate again. As far as I know only top mounted RF
use cams. good luck, Joe A

[Jack Dahlgren]

You can see the spring and how it should be in this photo: http://www.flickr.com/photos/jack-d/4350951490/in/set-72157623376499843
the large size should give you enough detail.

The second time through aligning it should be easier! It is good if you can set up a couple of different targets at the recommended distances. First time I did this I moved the camera back and forth.

[ethics_gradient]

The little spring wire does indeed have to be in it's proper place. Are you sure you're adjusting the right thing to get horizontal coincidence? It takes very little to do a lot. If you got it to focus down to 4.5 feet, youve done very well, as they weren't designed for use under 6 feet. Have fun.

Horizontal is the really long screw sticking out, isn't it? Applying pressure to the head with my finger I could get the images to line up, but I couldn't actually screw it in place like that. It looks a bit funky, the screw is at a slight angle and there appears to be some dried clear substance at the base of it, like it was repaired or something. By lucky coincidence, fixing the tension on the prism arm also seems to have put it back in horizontal alignment, which was a problem I was having even before I knocked it out of whack. Hopefully I won't mess it up while recalibrating vertical alignment tomorrow!

Are you sure about it being six feet? The instructions I had told me to focus it at infinity, 15', and 4'. I was a little annoyed that it stopped tracking a little before four feet, so I scooted my tripod back and kept trying until I got it to hit perfectly. I used three little strips of duct tape to mark the spots where my tripod legs were supposed to go as I moved back and forth between the positions.