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Kalart Rangefinder Infinity Stop / Alignment

 
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financephotog



Joined: 18 Feb 2021
Posts: 33
Location: Florida

PostPosted: Sat Mar 06, 2021 4:05 am    Post subject: Kalart Rangefinder Infinity Stop / Alignment Reply with quote

I'm trying to go through the alignment procedure (such as the one described on this site) for the Kalart Rangefinder on my Crown Graphic.

I can't get the inifinity setting to align: it seems like the long arm in the camera housing hits the RF's internal stop, before the pictures manage to align (movable image below still image). That means if I turn the eccentric screw further back to try to align the images, all that happens is it bends the arm a little, but nothing changes in the images.

Does this mean I need to adjust the prism?

Or alternatively, will the full adjustment described here help?

https://lommen9.home.xs4all.nl/kalart/new.html

In case it's relevant, the RF seems to be somewhat out of alignment in the rest of the distance scale as well. Could the infinity problem come from the rear slider being out of position? However, putting it on the right setting for my lens doesn't seem to help, so I'm guessing no.
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financephotog



Joined: 18 Feb 2021
Posts: 33
Location: Florida

PostPosted: Sat Mar 06, 2021 4:10 am    Post subject: Reply with quote

Oh, in case it is relevant, I have a 135mm f/4.7 lens and the camera is a 4x5 format.
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45PSS



Joined: 28 Sep 2001
Posts: 3996
Location: Mid Peninsula, Ca.

PostPosted: Sat Mar 06, 2021 6:28 am    Post subject: Reply with quote

Most likely the arm has slipped on the rangefinder shaft and requires resetting.
Take a salt tablet or two if you follow the lommen method. I found the distance figure he states to be off .5mm on average.

The set screw on the arm is 3/16. The end of the rangefinder shaft should have 2 flats, some do not.
With the eccentric on the yoke set to push the arm back the most, loosen the arm set screw, run the yoke in as far as it will go, hold the arm firmly against the eccentric, turn the rangefinder shaft reward as far as it will go and tighten the arm set screw with the mirror plate on the rangefinder body. It helps to have a 3/16 nutdriver on the set screw and use it to position the arm as well as tightening the set screw. I cut a slot in a piece of 1/2 wide, 2 1/2 inch long piece of .025 brass stock to turn the rangefinder shaft with.
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financephotog



Joined: 18 Feb 2021
Posts: 33
Location: Florida

PostPosted: Sat Mar 06, 2021 2:57 pm    Post subject: Reply with quote

@45PSS, thank you for all that. Project for the day today...

Will report back.
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financephotog



Joined: 18 Feb 2021
Posts: 33
Location: Florida

PostPosted: Sat Mar 06, 2021 11:13 pm    Post subject: Reply with quote

Success!! (I believe...)

Looks like I am one of the chosen few, for whom the shaft that goes through the camera housing does not have any flat spots at the end, but is completely round. At least I didn't notice any... Not knowing how to move the shaft otherwise, I decided to follow Lommen and take the mirror plate off.

Having done that, I checked for range of motion of the brass cam, and that actually looked reasonable to me. The left (rear, in terms of the camera housing) stop was at almost exactly 6 o'clock (just under 9mm from the inside edge of the housing; then again the edge has a diagonal slope so in thenths of mm it gets a bit imprecise). For the right end, the cam did not go all the way to the right housing, but that was because the arm stops when it gets stuck behind the hinge for the drop bed. However, since for this lens, that is so far towards short focus distances, I decided not to worry about that and to essentially say that the cam's motion was in correct relation to the arm.

In my opinion that left prism adjustment, so I did that. Half a turn clockwise on the prism screw solved it! That made it such that the arm now had enough freedom of movement backward in the housing so the moveable image ended up slightly on top of the still one. That put the eccentric screw in charge. Fiddled with it to get the infinity right; then I set the sliders to the book values for my lens, and did not find any more adjustments necessary at 15, 8, or 4 feet.

So that's it. On reassembly I then also made the rather satisfying discovery that my Focuspot's bracket actually comes off the Focuspot's tube. That made things much easier, as otherwise bayonet-twisting that thing into place at the same time as trying to get it into its right spot in the flash bracket seemed rather tricky...

So let's see how it works as I use it, but so far so good. I hope I haven't screwed anything up.

Thank you @45PSS for your help, as always! That was very useful for troubleshooting.


A few photos, if of interest:

- Brass cam, left (rear) stop:
https://flic.kr/p/2kHCsx2

- Brass cam, right (front) stop:
https://flic.kr/p/2kHyj6m

- Arm vs drop-bed hinge:
https://flic.kr/p/2kHBWhm

- Back of the mirror plate of the RF. Nothing to do with the repair, but how AWESOME is this gear train?
https://flic.kr/p/2kHCsAJ
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45PSS



Joined: 28 Sep 2001
Posts: 3996
Location: Mid Peninsula, Ca.

PostPosted: Sun Mar 07, 2021 2:11 am    Post subject: Reply with quote

I found that the 9mm distance was too close for some rangefinders, they required 9.5mm. I try to use 3 or more samples before posting such measurements.
I have two Century Graphics with rangefinder troubles. The Kalarts on them do not have flats on the RF shaft but have a hole in the front of the base that a #54 drill bit (9.055inch/1.397mm) just fits through that one can use to push the brass arm to the infinity position through.

There were in production changes to the rangefinders so the "text book" version may not match what you have.

Happy shooting.
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financephotog



Joined: 18 Feb 2021
Posts: 33
Location: Florida

PostPosted: Sun Mar 07, 2021 7:05 pm    Post subject: Reply with quote

Interesting, regarding the hole in the front of the base. I didn't notice that on mine.

Another thing I noticed, though (only slightly off topic): my Kalart RF is a "D" series serial number, so for lateral alignment it has that one big screw just below the mirror. The case is supposed to come with a hole so you can stick a screwdriver through, to perform the lateral alignment "live" while looking through the RF. The documentation I saw brags about weather sealing around that hole (which you would need!). Turns out on mine, over the years, that weather seal must have started to fail or something, and so someone epoxied a big ol' metal plate there to cover the hole.

Fortunately, the lateral alignment is really close on mine, so I am going to leave well enough alone on that.
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45PSS



Joined: 28 Sep 2001
Posts: 3996
Location: Mid Peninsula, Ca.

PostPosted: Sun Mar 07, 2021 7:32 pm    Post subject: Reply with quote

Kalart D54997 - 1950 Century Graphic - no external lateral adjustment, undrilled cast for one.
Kalart B95938 - 1949 Century Graphic - external lateral adjustment screw.
Kalart B09992 - 1947 Meridian - external lateral adjustment screw.

Hint: If you learn to See, have the camera level and the same height as the focus target, the lateral adjustment can be done with the cover off the rangefinder.
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