cmuseum

A chrome nose lens would have a silver breech-lock ring and this one does not look to have one. Given the reflection of the finger I'd think there is a filter on the lens.

Here are a few things you could try: * Dial in different aperture values and shutter speeds in Av and Tv mode and verify if the value displayed in the finder matches the dialed value. * Verify if the film speed and exposure compensation dial can be moved through the entire range. * Use another FD lens and check if that gets you significantly different exposure settings. * Use an external light meter (or estimate exposure settings by the sunny 16 rule) for a few shots and mix with automatic exposure settings on the same roll of film.

It's not just the mount that is different but the entire construction. With the New FD bayonet style mount almost the entire lens is rotated. Only the inner rear-most part of the mount remains in a static position. Breech-lock lenses are quite the opposite: The entire lens remains in a static position, except for the breech-lock ring. It is neither bolt-on nor a “conversion” which can be done with reasonable effort.

According to part numbers, for the very early line-up of chrome nose lenses there have been at least 2 different springs. I don't know for later S.C. and S.S.C. lenses. If I had to make a guess I'd say that more variants of the spring were added with the broadening lens line-up.

That's the positioning pin that ensures proper alignment of the lens with the mount. The mount has a slot matching this pin at the 12'o clock position.This pin has always been there since the early days of Canon R lenses and an adapter not having the slot is not a regular R/FLFD adapter.

Please note that the lower the aperture number is set the smaller is the movement of the ring. The movement is smallest at 1.2 or 1.4 and it is greatest at “A” (or green ring). The force that turns the breech-lock ring comes from a small spring inside the lens that also actuates the aperture signal lever. It's not a very strong spring as the camera has to overcome its force for transmitting the selected aperture number. The breech-lock rings are mildly lubricated and dirt can accumulate or the grease can get stiff. Cleaning and re-lubricating might help. Use very light grease. Theoretically, a mechnical issue with the aperture signal lever could also be the cause. But you already mentioned that the aperture is working well and hence this should be less likely.

Did you check if there is a film in the camera? It might be wound all the way to its end and block film transport now.

Left-hand thread is correct. Putting the two tiny screws back in their place can be abit tricky. A longer screw of the same size comes in very handy. If you don't have one try holding overhead. Please note that the lens in the video is the very first, non-SSC “chrome nose” version and might not be entirely identical to your SSC lens. The mount part should be pretty much the same, though.

Converter A and B can be combined with M39 extension tubes for building R/FL/FD extension tubes: I'd agree that Converter A and B are not found as often as Converter P but they are not exactly rare. These are all more or less recent ebay finds: I think the least common ones are the Converter E (Exakta) and N (Nikon), with the N version clearly being found least often and selling for the highest prices:

I think that will help only to a degree. Which still is better than nothing, of course. This is a picture of a T90 shutter with the rear shell and the closing curtain removed: The opening curtain rests on this little damper when closed. The damper deteriorates (you can see that it already left some residue on the edge of the shutter blade) and finally the curtain will stick. Same shutter with the closing curtain and the separator plate in place: It's not easy to see but some residue also gets onto the bottom edges of the closing curtain blades. Can this be cured? Well, unless you know where to get a spare (or how to make one, you 3D printing geeks) the damper can only be removed. But I don't know if the potential overtravel will damage the curtain over time. I haven't tried that. Disassembly down to the shutter requires unsoldering more than 30 connections. And I haven't found the time to do the reassembly yet.

Position of the aperture signal lever matches the selected aperture value. That makes me think the mount was correctly assembled. My next step would be removing and inspecting the diaphragm unit (again).

Use a macro focusing rail and focus by altering subject distance. Don't use the lens for focusing. Use a magnifier or an angle finder with magnification. Close the eyepiece shutter when taking a picture. (This won't help with focus, though.)

The pin indeed looks a bit worn. This is a close-up of a used but good one: The pin height should be 0.8mm. When the ring rotates the pin needs some room to move down the notch. So for the two extreme positions I wouldn't be worried about this position.

Here are some images of a New FD 28mm 1:2.8 (S/N 56xxxx range) with the mount removed: Aperture ring set to 2.8: Aperture ring set to 11: Aperture ring set to 22: Aperture ring set to A: Incorrect setting (lug of inner aperture ring does not match notch of outer aperture ring), don't assemble this way: Try the same configurations with your lens and compare. Pay attention to the position of the outer aperture ring, the inner aperture ring, the cam ring and the small lever actuating the aperture blades (11 o'clock position). The outer and inner aperture rings are linked by a lug (3 o'clock position in first picture) that can slide up and down while the mount is removed. It tends to disengage, watch out for it. The inner aperture ring and the cam ring are unlinked while the mount is removed. Look at the inside of the mount and you will immediately see what part fits the lug of the cam ring. Make sure they are match properly when reinstalling the mount. The small lever should always be touching the cam ring. If it is not, check diaphragm unit (again).

When you do keep the release button pressed, does the camera deliver the selected shutter speed? Or does the shutter stay open as long as you keep the button pressed?