Horseman 970: Rangefinder Not Focusing to Infinity

[Stephen Power]

I've had my Topcon Horseman 970 for about 2 weeks and yesterday managed to let it fall from the tripod onto a wooden floor.

Today, I noticed that the rangefinder is not focusing fully to infinity. You can see on the photo that the distance marker is not reaching infinity. When focusing, the rangefinder split screen won't 'match up' fully when focusing on objects in the middle-to-far distance and far distance.

UPDATE: I have (now) tried it with the focusing screen, and with a loupe on the Fresnel glass. I'm not convinced it's as sharp as it could be, but it's also not very blurred. It feels like it needs another fraction of a turn on the focusing knob backwards but the rail won't move any further.

I have the lens (105mm Professional Topcor) set to the correct infinity tabs and the correct cam is in place. The distance scale screen was cracked when I bought the camera. This was mentioned in the advert and I was assured that it did not affect the use of the range finder.

Does anyone have 1) any thoughts on if there is something simple that might be causing the issue and if not, 2) how to adjust the focusing?

Thanks for any suggestions.

 

[ic-racer]

 

[Dan Daniel]

Tracking down such an issue is not easy but it could be obvious. I'd start with any external linkages, see if a rod or cam got jolted out of position, came undone, etc. You should be able to manually move the rangefinder mechanism from the lens board.

Hard to know what to say without knowing how far in you are willing to go. So many places for it to be out. If you can remove the cover and expose the rangefinder mechanism, you might see the problem right off. Usually a jolt will be either linkage or optics shifted, but could also be needle jamming, zero point offset, etc.

After obviousl ankage ceck, first thing to to do is get lens board at stop, manually focus on ground glass on an infinity object, and see what is off in the rangefinder.

 

[Stephen Power]

View attachment 255132

I'm in Ireland. If needed, I'll look closer to home, but thanks anyway.

 

[Stephen Power]

Tracking down such an issue is not easy but it could be obvious. I'd start with any external linkages, see if a rod or cam got jolted out of position, came undone, etc. You should be able to manually move the rangefinder mechanism from the lens board.

Thanks Dan. See below for an update (mainly on what an idiot I can be).

 

[Stephen Power]

UPDATE: I've now managed to damage the camera even more, but at the same time the problem has been resolved (sort of).

I Googled a similar issue in an archived thread in a different forum. It was suggested that the focus may not be stopping at infinity, and a solution was to adjust an offset post at the end of the focusing rails.

I thought I'd found it (see photo) but when I used a screwdriver (as recommended in the thread) the screw thread sheared and the post fell off.

It seems to be a 'stop' to prevent the rails moving too far back along the bed. So, now, if I'm not careful, the lens can be taken too far back along the rails causing the spring on the cam to 'catch'. But, if I don't do that the additional fraction of a turn is there and focusing at infinity is perfect.

BTW, the rangefinder needle was always moving and it's now at infinity when the rails are in the right place.

 

[Dan Daniel]

Can't tell what that part does at all. Suggestion- step back a bit and give an overview shot before showing details.

On cameras like that, many screws are nice but not essential to function.

 

[Stephen Power]

Can't tell what that part does at all. Suggestion- step back a bit and give an overview shot before showing details.

I don't think it will be any easier to work out from this angle. It stick out below the rails, and catches on a 'stop' on the bed when the rails are moved back. Probably about 10cm is the max they would go with the bolt in place. Now, they go all the way back. But the cam sticks and the spring has to be released when the rails go too far back.

 

[Dan Daniel]

Put it in a bag, label it, put it in your camera bits drawer, see how to accommodate the missing part, and go shoot? Save it for a snowy winter evening.

 

[shutterfinger]

I would remove the shaft of the screw from the bed, find the diameter and thread pitch of the screw then make a new one. The threaded section of the eccentric screw head looks like its small enough to be driled out, threaded, and a new shank installed.
The screw is likely metric.

 

[John Koehrer]

Yup. It looks like there may be enough to measure the thread with a digital caliper. The nice
thing is in that size there aren't much choice in TPI and pitch. Using a metric scale you may find
it close enough to eyeball with a decent scale .

 

[Stephen Power]

Thanks @shutterfinger and @John Koehrer. The screw was holding a bolt or post of some sort, it can be seen in the photo above. It has sheared off completely and the rails can now move a millimeter or so back. This has allowed the camera to focus perfectly at infinity. I think I might leave it off. So long as I remember not to bring the rails back too far, it's actually working at it should now.

 

[Dan Daniel]

Hmmmm, maybe this has been gone over, but is that part an infinity stop? Looks to be an eccentric cam. By rotating the cam, you get a variable stop point, that you rotate until you get a true infinity stop?

 

[Stephen Power]

Hmmmm, maybe this has been gone over, but is that part an infinity stop? Looks to be an eccentric cam.

My thought was that the post that fell off was keeping the rails from going back too far. If I focus so that they move about 1.5cm back in from the edge, there's a 'click' and the cam seems to jam.

By rotating the cam, you get a variable stop point, that you rotate until you get a true infinity stop?

I have the cam sitting with the straight end flush on the bed, on the LH side. Is there another way to fit it?

 

[ic-racer]

Sorry if I'm not following as there are multiple threads on the topic. But my reading is that the camera fell and sheared a screw so the infinity focus of the rangefinder is no longer coincident with the image on the ground glass. In that case the infinity adjustment for the rangefinder is likely under the cover on the back of the camera (like the case of the VH-R shown here).

 

[Stephen Power]

Sorry if I'm not following as there are multiple threads on the topic.

Ouch. Not me Your Honour. I only made one thread about it, and it was then raised in another thread. Two max, honest guv'ner, and only one intended by me (honest, admin).

But my reading is that the camera fell and sheared a screw so the infinity focus of the rangefinder is no longer coincident with the image on the ground glass. In that case the infinity adjustment for the rangefinder is likely under the cover on the back of the camera (like the case of the VH-R shown here).

Not a completely correct summation. The camera fell. The next day I noticed that it wasn't focusing right at infinity. I saw a post in another forum (from 10 years ago), that suggested adjusting a post under the rails. I thought I'd found it but when I turned the screw it sheared off. The camera now focuses right at infinity, but the cam jams if the rails are taken back about 1.5cm (which the post was there to stop, I think). [Insert photo of a nutshell].

 

[BrianShaw]

Aren’t the flip-up infinity stops on the bed rails adjustable like they are on speed graphics? That’s one of the first things I would have verified/adjusted. If I’m not mistaken
the part that was sheared off is simple a limit stop... not intended to adjust infinity.

If the rangefinder is couple with a tube of balls and a spring strip connected to the sliding rails, it will likely continue to bind because it may be both too tight and in need if cleaning/lubrication. BEWARE: taking that apart is fraught with danger... the small parts get lost easily and all are needed!

 

[Stephen Power]

Aren’t the flip-up infinity stops on the bed rails adjustable like they are on speed graphics? That’s one of the first things I would have verified/adjusted.

They seem to be, yes, now that you mention it. If only you'd been sat next to me imparting your hard-won knowledge.

If I’m not mistaken the part that was sheared off is simple a limit stop... not intended to adjust infinity.

Yep, I finally managed to work that out, after I broke it.

 

[Stephen Power]

In that case the infinity adjustment for the rangefinder is likely under the cover on the back of the camera (like the case of the VH-R shown here).

Would you consider taking a wider shot so I can put it in context please? I can't work out where the adjustment is located. I don't think mine has it.

 

[ic-racer]

Check the lower right after removing the graflok back.