Leica M4 vs Canon 7 shutter and rangefinder design details

[mooge]

A few photos showing the some differences between the Leica M4 and Canon 7. Both are 1960s designs and both evolved from the Leica... uhh, whatever the original Leica was called.



1. Both cameras have similar layout. The only big difference is the placement of the slow speeds escapement, which is under the rangefinder on the Leica and at the bottom of the lens cavity on the Canon 7.


2. Top view.



3. Bottom view. Both cameras have a long flat spring for the shutter release button like on the Barnack Leicas.



4. Rangefinder/viewfinder units - front. The RF/VF design is completely different between the two cameras - the canon 7 RF/VF has two beamsplitters - one for the RF and one for the frame lines - while the Leica has one. I wrote a bit about the Canon 7 RF/VF here.




5. RF/VF - top view. On the Canon 7's RF/VF you can see the rangefinder mirror (far left) and frame line selector cam and lever (top of photo; five sided cam with slot in it).



6. RF/VF - back view. The Canon 7's viewfinder has a bigger exit pupil, higher magnification (0,8x vs Leica's 0,72x) and better eye relief (I can see the full 35mm frame with glasses vs on the Leica, it's a stretch). Overall the Canon 7's rangefinder is excellent, but not as good as the Leica's in a few respects.




7. RF/VF - bottom view. The roller is missing on the M4 rangefinder.




8. M4 rewind coupling. I'm not sure what this kind of coupling is called. You can also see the eccentrics for adjusting the lean of the shutter pulleys. This is supposedly to adjust for parallelism between the two curtains (so that the gap between the shutter curtains is even so you have an even exposure) but I didn't find that it does anything.




9. M4 high speed control and low speed escapement stuff. The low speed escapement pivots to change speeds, which is pretty unusual.




10. Canon 7 high speed control, counter and stuff. To my eye the canon 7 and Leica M4 high speed controls are completely different in layout, despite having similar (the same?) working principles and descending from the same design.




11. Leica M4 shutter brake (to the right of shutter drum) and X sync contact (copper bar on shutter brake). At the bottom of the shutter drum and to its left you can kind of see the gear with the missing teeth that winds the shutter drum. This gear is what makes the 'click' at the end of the winding stroke.
The canon 7 has a gear which is pushed out of mesh (along its axis of rotation) to decouple the shutter drum from the winding mechanism.




12. Leica M4 - thing to catch the closing curtain and prevent it from bouncing.




13. Canon 7 slow speeds escapement. It's in the same place on the Canon FTb (1974 SLR). The Canon 7 has device to prevent the closing curtain from bouncing as well, and to disconnect the slow speeds escapement pallets, but it's been removed on this camera.



14. Canon 7 vs Leica M4 size. Wow why isn't this photo sharp.





So, uh, yeah. If there's anything in particular you'd like to see, let me know because the cameras are both still open (well, the Canon 7 not for long)...

 

[retinax]

Very interesting stuff, thanks for sharing! Have you gone deeper into the shutter on either camera? I suspect that my Canon 7 would be grateful for a bit of cleaning and re-lubing, but haven't found any resources except the official repair manual which you probably know is pretty much only exploded diagrams... but I reckon the shutter functions pretty much the same as any Leica style horizontally running focal plane shutter and one could take instructions for any such shutter on where to lubricate?

 

[f16sunshine]

Excellent contribution!
Interesting to say the very least!
Great work.

I always loved the Canon 7.
My only complaint and it’s a deal breaker for me, the contrast spot in the viewfinder was often distracting.
Could probably get over it I had to but the M5 arrived at my door🙂

Cheers

 

[mooge]

Retinax - I've been deeper on both shutters; the Canon 7 recently and my M2 a while ago. I had to pull the shutter pulleys out of the Canon 7; that was a pain. Lubrication wise, basically you look at what it is and how fast it moves and lubricate accordingly.

But hey, if your Canon 7 works fine I'd say don't touch it.


Andy -
My only complaint with the Canon 7 (and why I didn't buy one before I got my M2) is that it's not M-mount and it doesn't have a shoe. The finder is pretty damn good in my opinion - but then again I've haven't used the Canon 7 much at all (I bought this one and immediately chopped it up...)




Oh, here's a top view of the Canon 7 escapement.

 

[retinax]

But hey, if your Canon 7 works fine I'd say don't touch it.

(...)

Oh, here's a top view of the Canon 7 escapement.

You're right, I certainly won't rip the shutter open completely, it seems to be tapering a little bit, but I'm not done testing how bad it is (when I want to up the contrast in post), I think I can get away with it for now. If there are places where a tiny bit of oil or grease won't hurt and can be applied with minor disassembly, I might just do that. We'll see, It'll be a while until I get around to tackle it anyway (should spend less time on the internet, then I could be sooner...).
That's a very simple escapement compared to that from a Compur shutter I cleaned recently, sweet.

 

[mooge]

A few more:


16. Top view of Canon 7 with shutter speed dial module thing removed




17. Shutter speed cam module, side view. There are six layers to the cam stack. from top to bottom (top in this view is bottom right):
1. Flash X or M sync
2. Slow speeds escapement deflection
3. Click stops
4. Escapement pallets on/off
5. 'T'
6. High speeds




18. A look at the bottom most cam, which I think is for high speeds only but maybe I'm wrong





19. Now on to my Leica M2 which is filled with dirt. Here we can see four gears - one out of focus to the far left, two in the center and one on the right, fixed to the shutter drum. The upper center gear meshes with the gear on the left and the lower center gear is what arms the shutter. The lower center gear has missing teeth so that the wind stroke can cock the shutter, and then leave room for the shutter drum gear to rotate so the shutter can fire. The 'click' you feel at the end of the winding stroke of a Leica M camera is this gear pushing the shutter drum far enough so that it can be caught by a latch, and then snapping into position so that the missing teeth clear the shutter drum gear. Kind of confusing to describe.

Maybe to put it another way - The shutter drum needs to mesh with the winding gear train for the shutter to be cocked when the film is moved. But if the shutter is to be fired, the shutter needs to be disconnected with the rest of the gear train. In the M-Leicas this is done with this gear with missing teeth; in the Barnack Leicas, this is done with a dog clutch on the takeup sprocket shaft which is pushed out of engagement by the shutter release button.





20. Another view of the gear with the missing teeth; this time partially wound so that the missing teeth are visible. Also visible immediately below the shutter drum gear is the lever that the missing tooth gear pushes against to push the drum past the latch.




21. Close up of M2 takeup shaft and casting mark on chassis. The casting mark indicates that the chassis casting was not produced at Leitz, but rather at a specialist casting facility - presumably the 'VDM' mark refers to Vereinigte Deutesche Metallwerke AG, which is now VDM Metals today.





22. Back to the Canon 7. Close up of the top of the shutter drum. The black cam with three slots with only one screw in it can be rotated relative to the shutter drum to adjust the shutter high speeds. The C-shaped lever below the shutter drum is what releases the second curtain when the shutter is set to a high speed.





23. Frame line selector cam on Canon 7. The positions are 35 (9 o'clock), 50 (6 o'clock), 85/100 (4 o'clock), 135 (2:30 o'clock).





24. Canon 7 self timer. The crossed slotted cylinder that connects the self timer to the lever on the body is called an Oldham coupling, and allows for some misalignment between the body and the lever.

 

[mooge]

Diving deeper into the M4...


25. Shutter speed cam module removed. in the fuzz of the background you can see the screwdriver I had to grind because one of the screws was obscenely tight, and I didn't have a screwdriver of that size with a big enough handle. That makes two screwdrivers I've had to grind especially for this camera, on top of the two sockets I made. And then there's the flex clamps.




26. Top view of shutter drum. The levers around it are for M-sync (2 o'clock), locking wind lever (I think, 3 o'clock), holding second curtain open (high speeds, 6 o'clock).




27. Bottom of shutter speeds cam module. The slots on the bottom-most cam (top in this view) is for the slow speeds and has slots in it to adjust individual speeds within the range. The cam surfaces at 12 and 11 o'clock have been pushed in. This adjustability is great, but then intermediate speeds are not accurate and adjusting the speeds this way is not easy since the entire module has to be removed, adjusted, reassembled and then checked - not simple or quick!




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28. Speeds cam module side (front) view.



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29. Slow speeds-escapement. The screw in between the fork tines in the center of the escapement is an eccentric and is used to adjust the slow speeds overall. This means that there are three variables in adjusting the slow speeds: Shutter tension, slow speed cam, escapement eccentric.
Other notable features left to right: hole for escapement pivot (the whole escapement rotates to adjust the shutter delay), to the left of the fork: slow speeds pallet lever and eccentric to adjust depth, far right: slow speeds cam follower (silver, top) and second curtain delay lever (black, bottom) which moves the geartrain of the escapement (producing that buzzing sound).



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30. Slow speeds escapement, bottom.



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31. Slow speeds escapement, side (rear) view.






32. Shutter brake. It's rather large and complicated (unnecessarily so?)- compare to the Canon 7's, center of camera, photo no.3.

The shutter brake serves to slow the shutter as the curtains reach the end of their travel. This damps the shutter vibration and prevents curtain bounce (closing curtain reaching the end of travel and bouncing back to overexpose part of the frame).

The plastic nub on the brake is for the X-sync contact - the X-sync is tripped when the shutter button is pressed and the first curtain is fully open.





33. Shutter brake, bottom. The screw is to turn a cam to adjust the preload on the shutter brake shoe; refer to the top view.




34. Shutter brake, exploded. The thing on the far right isn't even fully disassembled; it's at least 4 individual components.





Looking at this sort of stuff makes me wonder about the M camera today - what's been changed, and why? It seems like some things are unnecessarily overbuilt.
(anyone have a M6 or MP in need of a varsol overhaul? hahaha)

 

[mooge]

Just two more (for this session anyway, I need to get the M4 back in action)



35. Casting mark on the M4. It's different than the M2's, which is kind of interesting (to me anyway). No idea of which company it could be. If I recall the Leicaflex SL2 I worked on had the same casting mark (which would only make sense).




36. Shutter control cam stack. From top to bottom, they control:
1. M-sync
2. slow speed escapement pallets
3. ??? I forgot
4. High speeds
5. Slow speeds escapement



Oh by the way, I'd advise against removing the shutter speed cam module (photo 25) if you don't have to. On reassembly I got stuck on a couple of things (lost a spring, got a washer stack incorrect... somehow) and it took me something ridiculous to get back together (6-7 hours?). Lots of little bits that have to be exactly right and a bit of contortion required to get everything in order upon reassembly. The slow speeds escapement can come out without removing the cam module - unhook the spring and undo the screw.

 

[maddoc]

The best documented Leica M repair I have ever come across. Most excellent job in doing this. 🙂

 

[ForestCap]

mooge deserves a medal.

 

[mooge]

Thanks guys. Thought someone would find it interesting.


Oh yeah, I started an instagram account for this sort of stuff, where you can find a video of the slow speeds escapement in action, and not much else at the moment.

 

[mooge]

I cracked open an M4-P yesterday to clean the VF a little bit - didn't dive too deep but some of the changes between the M4/M4-P can be illustrated.



36. Top plate off. Pretty much identical to the M4, but with two phillips screws and a different shoe design (hot shoe). There's still the stack-o-washers under the rewind crank.





37. Front view. The body shell is fastened with phillips screws. The screws are accessible without removing the body covering (thankfully), which were then buried from the M6 until the M-A.





38. Top view. Note the hot shoe, and how the shutter speed dial is held on with a phillips screw, but nothing else is. I wonder why.





39. Vertical RF adjustment point - note that there's no eccentric here. Vertical alignment from the M4-P onwards (except early M4-Ps??? this is a 1981 example - 1 562 xxx) require a special tool to make the adjustment; basically the eccentric that would be here on an older Leica, with a screwdriver handle. The blue stuff is some sort of adhesive (like Loctite) which then locks the optical module in place.

I wonder how you're supposed to adjust the vertical alignment with the top plate on, since as soon as the optical module is moved, the adhesive bond is broken and there's not enough room to apply more adhesive through the access hole.

Special tools? NOT COOL. Overall, I'm not too enthused with this design change... although vertical RF alignment on my M2 and M4 is a pain in the derriere because the eccentric can be very tight and the eccentrics slots are somewhat rounded because of that. Rangefinder adjustment is the bane of my existence.





40. Frame line mask. Aside from there being 6 frame lines, the frame line mask is now (as of the M4-2???) etched metal instead of being photographic emulsion sandwiched between two thin glass sheets. This is great because the old glass sandwich style frame line masks could deteriorate (showing lines in the RF patch or frame lines viewed through the finder) or separate (like the old M3 finders), there's nothing for dust to stick to to be in focus through the finder, and having no glass in the optical path improves contrast. There used to be a small negative element on the RF patch aperture of the frame line mask and this is absent on the M4-P as well.





41. Naturally, I don't have any photos like No. 39 or 40 to show what the earlier M2/4 frame line mask and vertical RF adjustment point look like; so this quick and dirty shot of my M4 will have to suffice. You can see the eccentric screw for vertical adjustment; and sort of see the negative element on the RF aperture.

Interestingly enough, Cameraworks UK offers a 'free to air' frameline mask upgrade for the M2/M4 and it is like the M4-P frame line mask - etched metal, with no negative element. So what does the negative element do?





42. And a screen grab from the KS-15(4) repair manual, illustrating the frame line mask (6). The arrow points to the negative element I'm talking about.



I didn't dive any deeper than this, but the M4-P looks and feels as good / smooth / well finished as my M4 or M2. Sure, the design of the camera was changed (or some would say, cheapened), but none of the changes amount to anything that makes the camera worse in the hand of the user. And I think this camera's never been serviced before and it's running very well - not something that can be said too often about the pre-Midland cameras...

 

[lxmike]

thanks for giving us such a fascinating insight in to these wonderful cameras

 

[Jake Mongey]

This is fascinating! I have no personal knowledge or opinions to shed on the topic however, when I handed my canon 7 in for service the repairer said he loves repairing canon 7`s as they were "designed with the repairer in mind" he then stated that the leicas are fantastic but parts were crammed in without the repairer in mind.

Would you find that to be the case?

 

[ForestCap]

"when putting the top plate back on, the Canon engineers were thoughtful enough to provide this little shelf for the one side of the frame counter ring to rest on as the other side is in the slot in the side of the plate."

http://tunnel13.com/blog/1957-canon-l2-top-plate-removal/

Not 7 but an earlier model VL2. I used this article as guide when cleaning my L2.

I've seen some videos or picture-rich articles of Japanese repairmen changing Canon RF shutter curtains (V series and later). They simply removed the body shell (like a clam) and changed the curtains, without removing any additional parts. Not sure if it's do-able with Leica M.

 

[mooge]

This is fascinating! I have no personal knowledge or opinions to shed on the topic however, when I handed my canon 7 in for service the repairer said he loves repairing canon 7`s as they were "designed with the repairer in mind" he then stated that the leicas are fantastic but parts were crammed in without the repairer in mind.

Well... I guess. There's a few things much easier on the Canon 7; to name a few:

1. Body shell comes off with 10 screws and no special tools (awesome)
2. RF horizontal zero adjustment is easy peasy (RF rate... needs a special tool)
3. Top plate needs no special tools to remove other than a pin spanner
4. Slow speeds escapement easily accessed and removed
5. RF/VF assembly can be removed without messing up RF alignment (in theory)

compared to the Leica:

1. Body shell is... actually, not that bad to remove. Body screws, frame line preview lever (M4 style), loading diagram plate and a bit of wiggling. But then once the body's off you need to remove other stuff to actually get at anything.
2. needs screwdrivering at an angle to just any of the 3 rangefinder adjustment points
3. Needs two special spanners (!) and 3 different flexiclamps
4. Need to remove the slow speeds escapement? Gotta remove the RF/VF first
5. Gotta remove the RF roller arm to remove the RF/VF; which then requires major re-alignment upon reassembly

But there's things still a pain in the butt to do on the Canon 7. Taking the shutter speed dial off is confusing if you don't know what to set it to (for the record: ASA 400 and X; remove long setscrew at 6 o'clock and just loosen the others). Rangefinder alignment? Yeah, that'll generally be annoying; and the vertical takes time to "settle" as well (I've worked on two Canon 7s and both had to be re-aligned after about a week; then they were fine). But nothing's really especially annoying.

Yeah the Canon 7 is easier to work on, but I suppose the bigger difference is nothing really goes wrong with them; and what does isn't that bad to fix. Slow speeds is easy - remove the body shell, base plate and it's two screws to take the slow speeds out. Curtains don't really go bad because they're metal; and if they do you don't really need to remove the pulleys. RF alignment is annoying which is about normal.

I guess as a more concrete example - I got a Canon 7 and a Leica M4 this year, both with sticky slow speeds. The Canon 7 took less than an hour to get running again, and would have been serviceable if the RF wasn't off (and if I didn't put it aside to convert to M mount). The Leica M4 took something ridiculous - 5 hours of messing around? And I had to make custom tools that I didn't even need for my Leica M2. Sure, if I knew not to remove the shutter speed bridge it would have taken less time but it's much more involved than for the Canon 7.


The Leica Ms were certainly designed with elegance in mind - I imagine that the designer made the shape of the camera, and told the engineers to make the mechanisms to fit within this shape - and that's why things are sort of crammed in. I'm not sure I'd say it wasn't designed with service and repair in mind - the Leica is designed to last a long time, so serviceability must have been a consideration. I'll have to think a bit more about the differences in camera design philosophy at Canon vs Leitz were though - it's a very interesting question....

While I'm kind of ranting here, I'll complain about Leitz some more. The Leica M3/2 are brilliant cameras, no doubt. But I'm a bit disappointed that Leitz stopped trying to improve the M camera after the M5/CL - we're stuck with the M2 shape, and consequently the M2 finder, and shutter. Leica could make an M camera that is lighter, smaller (or not) and with a bigger viewfinder, but they won't because they're stuck with the M2 form factor. Their newest film camera, the M-A is basically a fancier M4-P, which is a slightly modified M2. This is great, if you like the M2, but the 1950s design of the M-A drives up the cost of the camera - 60 years on and it's still expensive to manufacture and difficult to repair.
Compare this with Nikon, who had the SPx designed as a successor to the SP (but never sold it due to the success of the Nikon F )- they kept improving the rangefinder camera. I'm sure Canon would have, as well. Leitz, and Leica... not so much.
(but mooge - there's no money in film cameras, especially rangefinders; the Leica is Mechanical Perfection™ yadda yadda yadda...)


Nukecoke - I did one of the curtains on my M2. Remove body shell, but then you have to remove a light baffle to get at the curtains - which requires removal of the rangefinder arm - which then means that you need to re-align the RF upon reassembly. So not horrendous but not as easy as the Canons.

cheers, thanks for the questions.

 

[kiemchacsu]

just pop up this thread again to ask mods if this one should be sticked on top.
thank you OP for putting the effort to record all these things.

 

[mikejd80]

Hi Mooge, come back again, working on my canon 7s now, and the shutter now stucks, film advance wont advance the film, any idea where to start, already took the top cover and body shell off, thanks.

 

[ForestCap]

https://www.rangefinderforum.com/forums/showthread.php?t=150721

Might help.

 

[mooge]

Hi Mooge, come back again, working on my canon 7s now, and the shutter now stucks, film advance wont advance the film, any idea where to start, already took the top cover and body shell off, thanks.

uhh well what state is the shutter in? wound or unwound? maybe poke at the interlocks around the shutter release rod - one blocks the shutter button when the camera is not fully wound and there is a latch at the bottom of the shutter drum that releases the shutter. I think. It's been a while.




RANDOM FACT: VDM, the company that made the casting of my M2's chassis (photo #21) was "the leading manufacturer of variable pitch propellers for the Luftwaffe, before and during WWII". You can see the VDM in a triangle logo on this pranged BF-109 B, for example.