Operations carried out
Cameras and lenses
Summarit 50mm f/2,5
When Leica gives up…
This lens had the focus ring almost blocked. By forcing a lot, it barely moved.
Too recent for frozen grease, its owner admitted that it may have received a shock (not good).
He also told me the astonishing story of Leica who told him “not repairable, trash” (it makes you think a little).
There is also a shift of the diaphragm mark in relation to the center of the distance mark.
Disassembly is a bit unusual, no unscrewing of the optical block like the Summicron, a rear ring that does not unlock anything…
To separate the helical ramps, you have to disassemble the bayonet, remove the depth of field ring, disassemble the two guides, and unscrew the helicals (of course by taking separation marks)
First intervention:
Degreasing and reassembly of the helicals to find the hard points and the braking more precisely.
The only solution is lapping as for the valves, using the finest granularity.
You have to proceed very gradually, without loading too much material at the beginning, then increase according to the result, but never stuff the ramps and force like a brute.
Little by little, the ramps are freed and end up returning to normal rotation!
It’s long; very long, I spent 1h30 and 12 reloads of material to arrive at a correct result.
It is then imperative to clean the ramps very well to prevent the residue of the lapping paste from polluting the grease when lubricating.
If this is the case, when rotating the ramps there will be small creaking noises as if there was sand…
In the video, you will notice, at the beginning, that the focus ramp and the rear turn freely, because there are no more guides, this is normal.
The following shows the optical block ramp at the last treatment.
Lubrication
In most cases, lubrication of helical ramps requires a thin film of grease.
After running-in, since metal has been removed, it is preferable to be more generous for the first pre-assembly.
Since the focusing ring is originally very fluid, it is the lubrication of the optical group ramp that will determine the smoothness of operation.
If it is too firm, remove a little grease and vice versa if it is too fluid.
For pre-assembly and grease dosage tests, it is not necessary for the ramps to be screwed in taking into account the separation marks mentioned above, the important thing is to determine the fluidity of rotation.
The rear part and the front part must be placed directly opposite each other.
Without forcing, you have to rotate the front part in the opposite direction of screwing (which is from left to right) in order to hear a small “click” which indicates that the ramps are in place for screwing.
You must then screw the ramps one into the other and make several rotations to properly distribute the grease.
Depending on the flexibility of the rotation, this determines whether the lubrication is sufficient.
You must carry out a focus check.
You just have to temporarily reassemble the bayonet with 2 or 3 screws and check on a device.
There was still a small problem, that of the position of the diaphragm indicator.
By its design, the optical block ramp is held by a ring at the rear and a locking point screw behind the aperture ring.
This screw had already been forced and it was unremovable.
As the position of the aperture marker does not pose a problem in use, it has been kept as is.
Reassembly is carried out, logically, in the opposite way to disassembly..
LEICA the legendary brand
I disclaim all responsibility if you damage your toys!!! There are also professionals to do this job!
