TenEleven
Well-known
The lens looked odd and an initial test on my Canon VI-L revealed that the rangefinder patch was offset by more than 2mm at infinity. I checked for mis-threaded helicals, but found none. Thus I considered it a "basket case" despite the relatively nice glass.
Today we're going to tackle this lens. It's most likely a one-off all brass custom job made by some machinist. My assumption is that when they found after all this work that the RF didn't read correct they gave up and left it as is. Or maybe it was never meant to give a correct RF reading? Interestingly the glass is correctly adjusted and tracks the focus scale perfectly. Also the focus scale ends up on the bottom of the camera.
(Image taken post repair)
The lens is relatively heavy at 230 grams. The optical block is made from alloy as per usual for a war-time lens - but the helical is an all brass construction. The lens also had a strong patina of use despite the misaligned RF - a bit of a riddle.
Taking it to bits we find a lot of very heavy duty brass screws securing both the optical block and the aperture. As well as the three brass parts that make up the mount for this lens. The lens innards are just your typical wartime Sonnar and thus I won't cover them in detail. I did the usual cleaning of the optics and aperture mechanism.
Better view of the helical and very thick set screws that hold the lens in place relative to the helical.
One strange and endearing detail was that the machinist had placed tiny cutouts for the three set-screws in the bit that slips over the aperture ring. They had also not tapped any holes into the aperture ring proper.
To fix the rangefinder displacement, I glued a thin brass ring to the rear of the helical. I found glue to be acceptable for this case as the part is very thin and not going to be under any mechanical (pull) stress.
Here's a closer view of the lip that has been created due to my brass ring being slightly broader than the base helical.
The lens is now all back together and has a nice shine of brass again.
Sadly it's not all smiles and sunshine....
When filing down the brass focus helical some of my polishing grease landed on the front lens. And I stupidly wiped it off instead of flushing it off, resulting in the weirdly "bacteria looking" bald spot in the coating you see above. Normally I keep the optics well away from my workbench when doing other work, but stupidly broke my own rule this time.
While I do not think it will affect imaging, I'm sure to get mad at myself all over again every time I see it...
Today we're going to tackle this lens. It's most likely a one-off all brass custom job made by some machinist. My assumption is that when they found after all this work that the RF didn't read correct they gave up and left it as is. Or maybe it was never meant to give a correct RF reading? Interestingly the glass is correctly adjusted and tracks the focus scale perfectly. Also the focus scale ends up on the bottom of the camera.
(Image taken post repair)
The lens is relatively heavy at 230 grams. The optical block is made from alloy as per usual for a war-time lens - but the helical is an all brass construction. The lens also had a strong patina of use despite the misaligned RF - a bit of a riddle.
Taking it to bits we find a lot of very heavy duty brass screws securing both the optical block and the aperture. As well as the three brass parts that make up the mount for this lens. The lens innards are just your typical wartime Sonnar and thus I won't cover them in detail. I did the usual cleaning of the optics and aperture mechanism.
Better view of the helical and very thick set screws that hold the lens in place relative to the helical.
One strange and endearing detail was that the machinist had placed tiny cutouts for the three set-screws in the bit that slips over the aperture ring. They had also not tapped any holes into the aperture ring proper.
To fix the rangefinder displacement, I glued a thin brass ring to the rear of the helical. I found glue to be acceptable for this case as the part is very thin and not going to be under any mechanical (pull) stress.
Here's a closer view of the lip that has been created due to my brass ring being slightly broader than the base helical.
The lens is now all back together and has a nice shine of brass again.
Sadly it's not all smiles and sunshine....
When filing down the brass focus helical some of my polishing grease landed on the front lens. And I stupidly wiped it off instead of flushing it off, resulting in the weirdly "bacteria looking" bald spot in the coating you see above. Normally I keep the optics well away from my workbench when doing other work, but stupidly broke my own rule this time.
While I do not think it will affect imaging, I'm sure to get mad at myself all over again every time I see it...
