Seeking Canon EF Camera Information

[jim_bielecki1]

4 hours ago, PO911 said:

I am still wondering, how the f-stop-metering (position of needle in viewfinder) is transformed into the correct aperture setting on the lens? Has to be some sort of delicate mechanics. Anybody here can explain this?

Thanks, Arno

Thinking back I'm pretty sure Canon used the "trap needle" system.  Once the meter needle stops moving and is set at a particular F-stop, an arm gently moves down and "senses" its position.  Through a series of linkages, etc. that position is transferred to the lens, so when you hit the shutter button, the F-stop you see in the finder is what the lens stops down to.  

[steven_endo]

The "A" or "○" position on the lens aperture ring is the magic. On the back of the fd lens, there is the aperture signal/control arm located on the side, in a long slot. As you turn the aperture ring, the arm rises or falls with the aperture. This arm couples with a lever at the side of a manual, match-needle metering  camera's mirror box that moves the circle that indicates the f-stop in the viewfinder.

When the lens is set to "A" or "○" on the EF, New F-1, F-1 with Servo EE Finder, and AE-1, the signaling arm becomes a control arm. A tiny little pin in the lens pushes a button in the camera's lens mount ring area which signals the camera to go into auto mode. When the shutter is fired, the camera closes the aperture and the control arm drops as usual. But the corresponding arm on the side of the mirror box stops and locks at a level that corresponds to the f-stop recommended by the meter. The arm in the mirror box thus stops the lens' control arm at the correct f-stop. Until the lens is set to "A" or "○", the arm in the mirror box is unused. That is why there is no manual match-metering in the auto exposure camera bodies besides the New F-1.

It is amazing to me that Canon was able to convert the R/FL mount into the FD mount.

Edited January 13, 2023 by steven_endo

[jim_bielecki1]

1 hour ago, steven_endo said:

It is amazing to me that Canon was able to convert the R/FL mount into the FD mount.

Well, don't confuse the actual breechlock mount with the R/FL/FD aperture mechanisms.  The mount just attaches the lens to the camera and is identical among the three, but the aperture actuating mechanisms are different, especially for the R-mount lenses, which share nothing with their FL/FD cousins.  

[steven_endo]

Oh, I realize that. But to go from nothing (?) in the R, to one auto stop down lever in the FL, to the various controls on the FD (including one "reserved" pin that was never used) is fascinating.

Makes me wonder if Canon was planning the FD mount when they designed the R or FL mounts (possible or probable?) or if they just found a way to stuff all the extra pins inside the mount.

And then, of course, dumping everything to make the EF mount which was a sad day for me...

Edited January 14, 2023 by steven_endo

[PO911]

Thank you Steven, Jim, for the good explanations! Good to see that there are some more EF enthusiasts here.

It is fascinating to see how the meter-needle position is transfered into the correct corresponding aperture-setting. All without electronics, just pure precise mechanics. I spent at least one hour last night just to examine all those levers...

Next thing, I will remove the galvanometer, since the aperture scale in the viewfinder seems to be stuck or disengaged. The more I deal with my "for parts only" EF, the more I am reaching out to get her back to life again 🙂 Fortunately the PO didn´t break anything as far as I can see.

Have a great week.

Arno

[PO911]

An old Copal Square S shutter never fails. 😄

I got the shutter to work as intended. Initially the mirror stayed open and the shutter did not close. The closing blades were somehow stuck (like oily aperture blades). Probably someone had sprayed some sort of lubricant in the past.

Long story short. I gave the whole thing, shutter blades and the complete shutter mechanism a good rinse with cleaning solvent for electronic circuits (Kontakt 601) that leaves no residue and does not harm any materials. After that, the shutter fired again with no problems. 

Only thing that does not work properly is the self timer. There are two tiny (very tiny) hair-springs that cock two small levers in this clockwork and those are missing. Does not affect the rest though. Anyone has a close up shot in high resolution of the shutter by any chance? Can´t find anything good on the net...

Thanks and stay tuned

Arno

 

 

 

[Lawrence Sheperd]

SN: 420890

Date Code: R732 (1977)

Split image/microprism

[gwhitegeog]

My EF is working beautifully still and I just put through it a roll of Fuji Velvia 50. Mine is 1976. The rear light seals need replacing, so that is the next job. 

[Bettendorf]

On 1/26/2023 at 11:43 AM, PO911 said:

An old Copal Square S shutter never fails. 😄

I got the shutter to work as intended. Initially the mirror stayed open and the shutter did not close. The closing blades were somehow stuck (like oily aperture blades). Probably someone had sprayed some sort of lubricant in the past.

Long story short. I gave the whole thing, shutter blades and the complete shutter mechanism a good rinse with cleaning solvent for electronic circuits (Kontakt 601) that leaves no residue and does not harm any materials. After that, the shutter fired again with no problems. 

Only thing that does not work properly is the self timer. There are two tiny (very tiny) hair-springs that cock two small levers in this clockwork and those are missing. Does not affect the rest though. Anyone has a close up shot in high resolution of the shutter by any chance? Can´t find anything good on the net...

Thanks and stay tuned

Arno

 

 

 

Let’s not forget that the data requested by the OP several years ago is to nail down the production history of the EF.

 

 

Edited April 11 by Bettendorf

[gwhitegeog]

Yes, it was a long series of posts, I wasn’t sure. Technically it was made ‘74 to ‘78. But did we want to know the production run? 

[Bettendorf]

13 hours ago, gwhitegeog said:

Yes, it was a long series of posts, I wasn’t sure. Technically it was made ‘74 to ‘78. But did we want to know the production run? 

Well, I tried to delete that post because it really doesn’t matter any more, but it timed out in the middle of it. 
Tim Witt was wanting to gather info on S/N, date of manufacture, and if yours had the newer focusing screen, in order to determine when that change occurred along with the number and date of the last one produced.

The post above yours by Sheperd is like what he was after.  It’s still a good read on a great camera!

[gwhitegeog]

Mine is P821 code and with split image / microprism focussing screen. 

[Bettendorf]

2 hours ago, gwhitegeog said:

Mine is P821 code and with split image / microprism focussing screen. 

Great!  Now if you just add your S/N to that info, you too can be a member of this 16 year old, Black Beauty thread Club.  😎

If you desire you can post it like this, 2793XX.

[gwhitegeog]

305917 ☺️