Don H Marks

Good as new!

Re-assembled to the correct orientation for the H8 with new grease.

The focus ring was cleaned and re-greased. Not it is nice and smooth.

The focus ring was still stuck. Under the thick grease is a locking screw that needs to be removed to get to the focus ring.

The focus mechanism came apart with exactly two turns. It was not that bad, but it was cleaned and re-greased. This one appeared to be simple threads with a single start location, not really a helicoid.

The grease had turned into something resembling wax.

Mark the focus mechanism before sliding the lens apart.

Three screws around the perimeter can be removed to access the frozen focus mechanism. If I plan on re-assembling in the exact same way, I remove the screws all the way, so the indentations can be seen to aid re-assemble. In this case, I will rotate the lens when I re-assemble it, so the index marks are in the correct place for the H8.

I picked up this mint condition Yvar 75mm lens for my H8 Bolex. The optics are perfect, but the focus ring is frozen.

I found a 75mm Yvar and it works great on my H8 non-REX with the adapter I got off e-bay. For those that don't use 8mm, the lens is useable on that camera because the H8 Octameter has a 75mm setting. After servicing the helicoid, it was easy to re-assemble the lens so the index marks were in the correct positon with the adapter in place. For this camera I want the index marks of all the lenses on the left side.

That is very nice, thank you for the link. I built mine to try time-laps to see if I like it before buying gear I might not use much.

A short video of the intervalometer in action:

The servo cycles back and forth and pushes the frame release forward via a spring-loaded lever.

I put together a simple intervalometer for one of my Bolex cameras. The design uses a Radio Control Vehicle servo and a simple 'servo tester' box that cycles the servo at various speeds.