Canon LTM Canon 7 lens mount wobbly...tightened screws. Cause for alarm?

[Forest_rain]

I usually used my Canon 7 with a 50mm 1.8 attached, and the rangefinder was aligned perfectly at infinity. Recently, I tried my 100 3.5 on it and the heavier lens caused the lens mount on the camera to "wobble", which threw off the rangefinder and caused it to misalign unless I put pressure against the lens mount to center it.

Seems like the issue was 4 loose screws on the camera lens mount - all 4 were loose and there was some give on all corners of the mount.. I tightened them, not too tight, until they stopped turning, didn't force them at all.

However now, the rangefinder image aligns just a hair to the left of a distant object at infinity. Not much, but a very small distance.

Seems like this may have altered the flange distance (not sure if this is the correct term).

Will this be an issue or is my OCD getting the better of me again? I'm not sure why all the screws were loose to begin with, perhaps the previous owner had tried to adjust the distance slightly.

I've got film in the camera, should I remove it, put ground glass on the film plane, and assuming the focus is sharp(ish) at infinity, just leave it be?

I don't have any means to measure the flange distance, I could purchase cheap electronic calipers for about $10 but I'm not sure if it would work/fit inside the light baffle cavity inside the lens mount, or otherwise what type of calipers I'd need.

I've heard the flange distance being off may be an issue with wide angle lenses moreso, I don't have any at the moment.

Here's some pictures of the lens mount, I compared them to pictures on eBay, some of the eBay examples seem to have slightly more distance/give on the lens mount, others look similar to how mine look now that I've tightened the screws a little....

 

[Phil_F_NM]

Finish your roll of film.
You are shooting a camera that is at least 50 years old and you setting the flange focal distance to 28.8mm is going to lead to a domino effect of adjustments.
The best bet is for you to tighten the flange screws, place a small groundglass on the INNER film rails at the film plane and ensure the 50mm lens focuses at infinity (the outer ones are usually about .2mm different to account for the thickness of the film itself). You've had other cameras apart but you need to honestly assess your skills at camera repair in order to make this adjustment. You don't want to mar up the top plate or make tool marks on the screws. This may lead to you having to adjust your lens for infinity as well. If you don't want to create a pretty doorstop, you may want to think about sending the lot out for a proper CLA. That's what happens to every Barnack Leica that is purchased used just because they need it. Most cameras and lenses need it after a few decades. You don't have a baseline of how the camera and both your lenses perform yet anyway, so don't worry about it. Usually the worst condition gear to buy used is that stuff that home hobbyists and obsessive cleaners have tinkered with until they damage the bits, either rubbing the coating off, leaving prints/oil/hair/dust inside lenses, or buggering up screws with ill-fitting screwdrivers and a lack of patience.
Get a better strap though. Those old school clip types will scratch the crap out of your camera.
Realistically, just shoot your gear stopped down a bit and you'll be fine.

Phil Forrest

 

[Forest_rain]

Fair enough. I'm going to finish the roll and hoping it doesn't make a big difference. Yeah, I'm realizing the camera is old and I can't expect it to be perfect. I just hope the tightening of the screws won't mess up the infinity focus too much.

Will see once the pictures come out.

Tell me about it, these old rangefinders are giving me a headache 😉

But the last pictures were great - I think they're worth it.

Finish your roll of film.
You are shooting a camera that is at least 50 years old and you setting the flange focal distance to 28.8mm is going to lead to a domino effect of adjustments.
Realistically, just shoot your gear stopped down a bit and you'll be fine.

Phil Forrest

 

[rfaspen]

Agree about the strap. Those old big metal attachments (usually on those "Hippy straps") were murder. The damage can be more than cosmetic.😱 Hate those things!

Your camera has an unknown history. We will never know what has happened to it, or why.

I had a Canon IIF that some previous user insisted that the little arrow on the wind knob was incorrect and forced the knob to wind on film in the opposite direction. Jeez! Other than that I thought the camera was excellent. I tried to fix the mutilated clutch myself (the wind on mechanism) and it became obvious it was above my skill level at the time (but such an obvious fix). I sent the camera to Don Goldberg (DAG camera repair) to fix the clutch. The man is so nice, he did a mini CLA of the remainder of the camera without asking and charged only for the clutch fix. Wow. The camera is spot on, a joy to use, and I had no idea the difference between the typical ebay arrival and what a camera should actually be like.

Moral of the story: if you want to end the headaches and nagging worry, pick your favorite rangefinder and send it to a highly skilled/respected repair person (ask us here on RFF for suggestions) and bite the bullet on cost. The result will be a good camera that you can then just use without all these little nags. I understand the reluctance to spend a fair bit of $$ on something that seems intangible. I really do. But I'm glad I made the leap -- in fact I've made that leap several times since that IIF. Always to Don (and I still feel that reluctance part).

Provided your Canon 7 is in good shape in terms of wear and all the parts are there and undamaged, Don (DAG) can transform your camera. Clean out offending gunk. Likely make the viewfinder much nicer, Put everything thing in the correct adjustment to proper tolerances with proper lubrication. He can't always work miracles, such as making missing parts appear magically, but some say he still works magic. I'm fairly certain he will work on Canon 7's, I know he works on the closer Barnack types (e.g., IVSB or IIF).

And I should say that I recognize there are some of us around who do indeed enjoy the challenge of fixing these old cameras. We go into this with eyes wide open and complete understanding of what's before us (and expectations). Its a different mindset, but quite valid. Proper home repair ends up being just as costly as sending them out though. I've got a lot of $$ invested in specialized tools, and even tools to make tools (ask if your curious), etc. And I still send things to Don. I have lens that needs his attention now.... its way beyond me.

 

[Mackinaw]

Fair enough. I'm going to finish the roll and hoping it doesn't make a big difference. Yeah, I'm realizing the camera is old and I can't expect it to be perfect. I just hope the tightening of the screws won't mess up the infinity focus too much.

Tell me about it, these old rangefinders are giving me a headache 😉

I bought an old Nikon M rangefinder 10-15 years back. I had the camera, and 50/2.0 lens, CLA'd and it came back looking and operating like new. Over the years, the lens has developed a slight wobble. Part of me says "get it fixed, your focus will be off." The other part of me say's "no big deal, live with it." The "no big deal" side is right, in reality, all of my pictures are sharp, and the lens focuses just fine (wobble or not).

Jim B.

 

[Forest_rain]

Sorry to beat a dead horse. Well, I'm thinking that I may be splitting hairs here. I just got my roll back. I don't think that such a small change as tightening the screws on the flange will change much... But I did an infinity focus test on a tripod using self timer on a distant object.



Focus point is the house with the red roof in the distance. *The 50mm images are cropped so resolution won't be as good as the 100mm images* All set at infinity. First picture is the worst, its wide open at 50mm @ F1.8. I'm thinking that the fungus/haze on my lens is at fault here and not the infinity focus. House is pretty soft. Rest of the images show the distant house to be in focus at infinity. 100mm has no fungus.


Look OK to you guys? Infinity focus intact, now just re-callibrate the rangefinder with this point at infinity?



50mm @ 1.8. Pretty bad, but my lens has haze/fungus.

50mm @ 5.6. Much better this time. Red house is in focus and less soft. Still softer than the 100mm though.

100mm @ 3.5. Sharper but I cropped the 50mm image, so the resolution will be better here, that might be the reason the red house appears sharper.

100mm @ 5.6

Infinity @ 100mm 5.6

 

[Phil_F_NM]

You're into the territory of focus shift according to the aperture at this point. No lens performs well wide open at infinity, aside from those atop Mauna kea and similar optics designed to do so. Your 50mm Canon is not one of those optics. Keep it dry and protected from bumps. Get it and your camera CLAd when you can, but until then don't stress, just use it.
Phil Forrest

 

[Forest_rain]

Thanks for your advice Phil as always, useful as this is like buying your first used car. You must be up pretty late considering I'm usually the only one around in Hawaii hours at night 😉


Just got a 135mm 3.5 with perfect glass in the mail, looking forward to trying it out.

You're into the territory of focus shift according to the aperture at this point. No lens performs well wide open at infinity, aside from those atop Mauna kea and similar optics designed to do so. Your 50mm Canon is not one of those optics. Keep it dry and protected from bumps. Get it and your camera CLAd when you can, but until then don't stress, just use it.
Phil Forrest