Bolex Kern Switar 5.5mm f1.6 Stiff Focus and Bent Stop Down Lever

ic-racer · Mar 9, 2024

Kern Switart 5.5mm f1.6 H8 RX lens has a very stiff focus. Also, someone buggered the stop-down levers. Maybe dropping the lens in the past. The levers were both bent.

For years I lived with the bent levers, imagining they would break off if bent back. However, during the repair of the stiff focus, I realized the lever was not actually bent. It was the ring to which the lever is part of, that was bent. So I was able to bend the surronding ring back to shape and the lever came back to position.

ic-racer · Mar 9, 2024

As with many of these lenses, by removing the perimeter screws on the foucus ring, the lens comes apart.

To be safe for re-assembly, make some marks and measure the length of the lens.

ic-racer · Mar 9, 2024

There is a single pin and slot for re-alignment of the focus helicoid during re-assembly.

After removing the fous helicoid, it was clear that the focus ring (still attached to the body of the lens) was the culprit. Very hard to turn.

ic-racer · Mar 9, 2024

The focus ring is held in place by this soft aluminum retaining ring. It was very tight.

ic-racer · Mar 9, 2024

Cleaning this took almost an hour. In the past I had buggered up the outer finish of the lens with alcohol (my favorite cleaning solution). Seems the paint on these lenses will come off easily.

So, I had to be real careful no cleaning solution dirpped on to the barrel of the lens. It was not like I could just plop this whole thing in solvent.
Neither alcohol or acetone were all that great on removing the solidified grease. It was very slow going.

After getting it as clean as I could, I put it back togeter and it was still stiff with grease.

Eventually I got it 'better than it was' and left it at that.

ic-racer · Mar 9, 2024

I marked the focus helicoid 'start' location and measured the length before unscrewing it.

The mounting threads on these lenses spin freely on the barrel so the lens can be attached without spinning the whole body of the lens. Otherwise the stop-down levers would hit the adjacent lenses.

To keep the mounting threads and that knurled ring from spinning, I screwed the rear cap on. The friction there keeps everything in place, so my marks won't move.

ic-racer · Mar 9, 2024

ic-racer · Mar 9, 2024

ic-racer · Mar 9, 2024

After cleaning, I re-greased it. Everyone has their favorite grease.

When replacing the 3 screws on the focus ring, one can look inside and see the indentations were the screws were to make sure the ring is back in the same place. Otherwise the lens will need recollimation for infinity. Not something I wanted to do with this lens as this is so hard to focus. This is a 5.5mm lens so, with the lens wide open, the marks on the barrel indicate depth of field from infinity to 2 feet. This is much shorter lens than Minox, which is 15mm.

ic-racer · Mar 9, 2024

Lens is much improved. The stop down levers are no longer bent down and the focus is much easier.

awty · Mar 9, 2024

Nice work. My 5.5mm Pizar has combined focus and aperture, not sure how that works, I don't have a Reflex 8mm to test it out.

BAC1967 · Mar 9, 2024

I was just looking at a 5.5 Switar in D mount that has the same problem. Hopefully it comes apart the same way.

ic-racer · Mar 10, 2024

awty said:
Nice work. My 5.5mm Pizar has combined focus and aperture, not sure how that works, I don't have a Reflex 8mm to test it out.

It is fixed focus. It "focuses" based on depth of field.
The main reason the Switar has a focus ring is for macro; it goes down to 4 inches.
Otherwise zone focusing is good for both lenses for distant scenes.

Bolex Kern Switar 5.5mm f1.6 Stiff Focus and Bent Stop Down Lever

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