nick_zima said:
Jay
Thanks for this very full explanation: I can see what you mean about the top part of the lens mount being indented on the reverse at the top.
The camera is marked NKVD-SSSR Khar'kovskii Kombinat im. FEDzerzhinskogo (is that a 1-d model?)
Would it be more realistic to disassemble both lenses and 'transfer' the uncorroded diaphragm to the lens which belongs to the body? Perhaps I should say 'get someone else to' as I'm not sure how realistic it would be for me to tackle the job!
best wishes Nick
Nick
What you've got is a pre-war FED "NKVD". These are rather difficult to work with. To begin with, the NKVD FEDs had a lot of variations in the FED line in terms of lens mount and register. All the NKVD are found (unless the mount's been changed) with non-Leitz standard thread mount pitches. Leitz' mount thread used M39X1 inch , whilst the NKVD thread was M39X1, metric. The FED mount adopted the Leica standard after WWII.
Like the pre-O Leica cameras, the focal registers (lens flange-focal plane) of the prewar and early post war FED varied. Leica had standardised their focal registers (in soviet literature, termed as
'working distance') at 28,8mm. The early FED averaged at 28.5mm, with variations as high as 0.05mm. When their lenses were produced, their back focus lengths were not standard so the cameras they went into had to be individually adjusted to suit these lenses.
Lenses from different NKVD cameras would not even readily interchange. A lens from one NKVD whose focus tab parks in an ideal position in that camera will likely have this tab park over the viewfinder in another NKVD camera. Such had been my observation amongst the NKVD FEDs I have.
Another issue with swapping lenses on NKVD FED is that the actual focal register distance of the lens is hard to determine. You would have to determine first what the actual focal register- exactly to 0.02mm- of your replacement lens before you can establish the new focal register adjusments for your camera.
Transferring lens components between lenses is also not recommended. The more original the components you have, the better the performance of your device is. Many of the parts were custom-fitted to the devices they were found in. Are the diaphragm blades deterioated beyond repair? Can't they be cleaned anymore?
You have two options here: replace the original lens and get a 1950s FED-50 or Industar-50. Replace the lens mount with one from a later FED-1 or Zorki-1. The lens mount from Zorki-C or Zorki-2C will fit on the FED NKVD. Recalibrate the camera's focal register, as well as its rangefinder, to suit the replacement lens. Recalibration in this case is easier since these lenses have 28,8mm registers and the camera needs only to be adjusted for this value. In the end, you'll get a fully functioning FED-1. However, authenticity, historical value, and considerations like shooting with an uncoated vintage lens are all lost.
Second option is to have the lens diaphragm repaired, taking care that the lens adjustments are not disturbed during the process. You need not touch the camera anymore, assuming that it has retained its original calibrations. This option will probably cost more than replacing the parts to make the camera functional. But the working FED NKVD you get in the end will allow you to shoot through a camera the way it was in the 1930s.
Click on the link below my signature (FED Zorki Survival site) for more FED info.
Jay