Canon 7sz top cover removal and cleaning

[Daimon]

Following my GAS ordered another LTM camera - this time Canon 7sz.

Wanted to disassemble the top cover to clean optics.

Haven't started unscrewing anything but already noticed that flash sync port does not have slots like in most online photos



How it should be unscrewed? By looking at some online guides, internal brass looking part is the one holding the outer ring and not the other way around

 

[Mackinaw]

Looking at my 7sZ and at my 7s repair manual, the inner flash terminal has to be removed to remove the top cover. The outer chrome trim ring also screws into the body. I'm guessing you have to remove the outer chrome ring, then remove the inner flash terminal.

Jim B.

Addendum: This discussion on Photrio may be of help:

Canon 7sZ top cover removal

I have a Canon 7sZ rangefinder camera that I would like to work on, specifically removing its top cover to clean up the rangefinder mirror/prism assembly. I have the service manual for the 7s, but the 7s vs. 7sZ flash syn are different. The 7s simply unthreads, but I can’t figure out how to...

www.photrio.com

 

[Daimon]

Yep saw that thread on photrio but other than mention of the same problem I don't think there was any conclusion about actual working solution there.

Only thing which was actually mentioned is that it was not possible to unscrew the outer ring first 🙁

 

[santino]

A custom built tool might come in handy that grabs the ring from the inside of the flash socket but who knows how tight it is. Other option would be some sort of friction tool or to cut a small slot in the brass ring. Either way the ring is small and probably not easy to remove.

 

[GMOG]

Could the sync port come off with the top plate, unlike the other Canon models that are similar?

 

[Sonnar Brian]

Following my GAS ordered another LTM camera - this time Canon 7sz.

Wanted to disassemble the top cover to clean optics.

Haven't started unscrewing anything but already noticed that flash sync port does not have slots like in most online photos

View attachment 4828805

How it should be unscrewed? By looking at some online guides, internal brass looking part is the one holding the outer ring and not the other way around

I had one that looked like this, someone had replaced the flanged ring with one like this- was not a Canon 7s or 7sz.
I used a hollow rubber grommet to get around it, squeeze, and unscrew it. I probably squirted is with some ronsonol (lighter fluid) to lube first. Was more than 10 years ago.
When putting the top plate back on, make sure the frame line selector correctly positions in the mechanism. The plate will look tight, but will be slightly raised. Make sure the framelines can be changed before putting all back together.

 

[Daimon]

@Sonnar Brian I checked several "7sz" listings on eBay and it looks that they all have this kind of port without notches.

Just to be clear about your approach - you unscrewed outer chrome ring first or managed to unscrew inner brass port first?

 

[Sonnar Brian]

@Sonnar Brian I checked several "7sz" listings on eBay and it looks that they all have this kind of port without notches.

Just to be clear about your approach - you unscrewed outer chrome ring first or managed to unscrew inner brass port first?

This was done years ago: I remember the outer ring coming off, but no longer have the camera.

Looking at the Canon 7s: At some point the design was changed. The Canon 7 and early 7s have slots to unscrew the inner connection first. This mechanism was replaced. You would not be able to unscrew the inner section first without the slots. The outer ring- can be gripped and unscrewed.

 

[Daimon]

Managed to grip outer ring with a flexi clamp and get it moving - but now it just rotates without any friction - same as in "photrio" thread which was linked here

 

[Mackinaw]

Just a guess, maybe it's pressed in, not screwed. Maybe you have to "walk" it off.

Jim B.

 

[Daimon]

Hard to tell - don't want to risk irreversible damage if I try to force pry it - that's why i'm looking for some examples which actually did work.

Grabbing outer ring and moving it in CCW direction it definitely created a bit of loose space between chrome ring and brass part - "maybe" just by friction between the too, brass port unscrewed a bit during process. But when I take a sneak peak there I don't think that chrome ring could go off without the brass port first.

 

[dxq.canada]

I think the outer ring is just a decor ring that is pressured on by the inner part.
The inner part is actually screwed onto the inner body shell.
Use a friction tool to turn the inside part.

 

[Daimon]

Ok got it out. First clarification - brass port is the part which needs to be unscrewed. Chrome ring is only decorative as mentioned above and is held by brass port.



Eventually it took 2 steps.

I first used flexi clamp on chrome ring but it was not getting enough friction. Had to use trick I know from a different hobby (rifle scope mounting). Added a bit of powdered resin which greatly increases friction. Grabbed chrome ring with a clamp covered in resin and managed to move it. It itself because of friction unscrewed brass port a bit.



Then I 3d printed PETG insert with very tight measuring so it had to be pushed inside brass port. Then used pliers on insert and managed to unscrew the port.





Ideal tool would be "outer grabbing flexi clamp" so I could catch brass port from the inside but unfortunately don't have those. 3d printed insert would not work from the beginning as significant torque was required to start it moving (that was achieved with a clamp on chrome ring)

 

[dxq.canada]

I could envision that Canon would have make a custom tool for their Tech's to clamp the inside outward to be able to grip it and turn.

 

[Mackinaw]

I've been trying to figure out why Canon used an ordinary flash synch (most likely from their SLR parts bin) instead of the slotted flash synch used on the Canon 7 and early 7s cameras. I'm guessing with 7sZ production winding down, they ran out of the slotted synch terminals and didn't feel like making anymore. Ditto with the SLR-style large rewind crank. They ran out of the small ones and used something out of the parts bin.

Jim B.

 

[Daimon]

Anyway 7s/7sz is actually very nice camera - both visually and feature wise. Had to fix slow speed mechanism (that's actually strange because camera looked like it was never opened but slow speed mechanism was not engaging at all) cleaned fungus from the inside (internal rotating RF window is interesting concept 😉 ) and ended up with perfectly bright framelines, good rangefinder (better than Canon P) + fully working meter (after aligning gives the same readings as my modern flash shoe meter). Price wise is cheaper than Bessa R (eBay)

 

[Daimon]

Some additional hints in case someone else takes this route in future:
- viewfinder eyepiece looks to be same like in Canon 7
- main prism and vertical adjustement RF window are installed differently - in my case main prism was clean so just had to clean the internal RF window which was easily accessible after top cover removal



- RF mirror looks to be just a silvered glass (coated layer is not protected by anything) - cleaned it very gently with Zeiss lense cleaner but as silvering is not protected special caution is required



- light meter window has to be in "low sensitivity" (covered by iris) position for top cover to lift off and install back - it's not required to remove it



- top cover rangefinder window is masked from inside by black paint - be very careful there when cleaning. In my case paint looked to be water soluble and started to go off with a touch of cotton pad slightly rinsed by zeiss lense cleaner and ended up with slight repaint job

On same photo it's also visible that mirror itself has a very unclean cut. It does not affect function in any way but does not look solid



- when I tried to unscrew rewind knob it did not unscrew from the top. Film casette "link" unscrewed from the bottom of rewind shaft. Had to remove knob together with rewind shaft. Camera keeps shaft with a spring but it looks to be a tensioned wire instead of detent ball - it was not possible to put shaft back in as it was blocked by the wire. Had to 3d print a pilot and managed to install it back this way

 

[Duofold RF]

Excellent work, kind of tricky to remove the flash socket

 

[Mackinaw]

Yes, really, a great writeup and pics. I thought about cleaning the viewfinder of my 7sZ but, after reading all you went through, I think I'll just leave good enough alone.

Jim B.

 

[Duofold RF]

I think use a good firm rubber block can unscrew the flash socket too