Bolex Eye-Level Focus Finder Restoration -- This Is What I Found...

My beloved Bolex non-Reflex camera came to me in 1990 with a broken eye-level focus eyepiece (yellow circle). Apparently the camera was dropped at one time and landed on the eyepiece. That drop tore out the screws and when it fell apart, the lenses in the eyepiece fell out so it could no longer focus. I cobbled together some parts and got it to kind of focus but it is not a clear image.

For many years I have been looking for the eyepiece, or the whole assembly. I even considered buying a whole non-working camera just for the eyepiece, but prices on these cameras have gone up recently.

For those of you not familiar, on the top of the camera is a window that shows the view of the lens in the upper-most pisition. This is NOT the taking lens position. But it allows you to focus that lens, then swing the lens to the taking position for filming. That is how one focuses these cameras.

In practice, especially with neutral density filters (like in the image below), I focus with the 35mm long lens. Then transfer the distance to the scale on the taking lens. The 35mm always has a finer focus scale than the shorter lenses. For example the 35mm lens might focus on the subject indicating 30 feet. That is then easily transferred to the 5.5mm lens which has marks at 15 feet and infinity 1mm apart and a depth of field scale showing 3 feet to infinity in focus at f 1.8 !

What the Eye-Level Focus Finder does is allow one to view the little ground glass focusing image from the back of the camera, rather than the top. At first, it was an accessory for $37.75 in 1952 ($437 today!!) , but eventually all the non-Reflex cameras came with it standard.

So, after years of searching, I did find a wiewfinder on the internet.

It looks reasonably clean on the outside, but...

...the optics are pretty much opaque.

So, I will disassemble this and see if these lenses can be cleaned. Maybe, maybe not.

First step in disassembly is to remove the eyepiece. The first screw head broke off when I just touched a screwdriver to it. Maybe this eyepiece has had a crash landing too, causing it to fracture? There is some damage to the eyepiece rim.

These are in pretty bad shape. Good news is that this viewfinder has never been disassembled, so no one has yet tried to clean them. I found that if a lens has already been taken apart, and someone tries already to clean the glass, and they don't come clean, I don't have any special treatment for that.

I was surprised! These cleaned up very nicely. Just some rubbing and some alcohol. One lens is convexo-convex with two different curvatures and the other is plano-concave. I marked their orientation in my notecards. They touch and form a doublet, but they were not ever cemented together.

At the end of the device there is a cap, under which lives an adjustable 90 degree prism. The adjustment will be fine-tuned later.

There are three tiny countersunk machine screws holding the prism assembly in place.

With the prism out of the way, the next potential disaster awaits. This lens actually looks fractured.

There is a larger slotted head screw holding the middle lens assembly in place. It is adjustable. I noted the adjustment position (red arrow).

Removing that screw allows the central lens block to come out.

It turns out these lenses are not broken. I soaked the assembly in alcohol to loosen the retaining ring. I did not want to break the glass, trying to remove the retaining ring.
As it turns out, some firm pressure on the glass from the back was able to push the retaining ring out.

Again, rubbing with microfiber cloth and alcohol removed all the dirt. There was no, or at least only minimal damage to the lens surfaces.
Make careful notation of the orientation as neither lens is symmetric and there would be eight different ways to re-assemble them if they got mixed up.

More evidence that this finder had been dropped at some point. The front attachment clip is clearly bent. (orange arrows)

I was able to squeeze it back into its proper shape with a table vice.

At the eyepiece end, there is a diopter correction assembly. It was frozen in place. Some light oil freed it up so it could be removed.

Again the lens looks nearly opaque.

This moving assembly has a single non-symmetric glass element, held with a retaining ring. Gentle pressure from the rear allows the ring to pop out from the front.
Thankfully, this lens, like the others came clean!

That is it. Next step is to re-assemble all the cleaned parts.

Last step is to confirm the image is in the center of the optical path. The three adjustment screws on the prism assembly allow fine tuning of the position of the image.

Nice job!

Here it is ready to go. Wow, so much easier to use. Because the lenses in the eyepiece had fallen out, I had to take off my glasses and squint to try and focus. Now I can see a bright, large and in-focus view through the focusing lens.

The astute observer may have seen that the Eyelevel Focuser I got was for H-16 and my camera is H-8. The focusers are different, but only in two pieces.
The diopter adjustment is different and the middle lens block is shifted forward with a bracket and a spring. So I was able to take the best parts from both and make one good functioning H-8 focuser.

Those that are interested, this camera wears a 13mm f0.9 Switar Visifocus, 36mm f1.8 Switar Visifocus and 5.5mm f1.8 Switar lenses.
This is my low light camera. It has the f0.9 lens and slower effective shutter speed, due to no light loss from the reflex prism in the REX models.
I shoot 18fps which is about 1/50th second exposure with this camera.

Full adjustment instructions from the manual:

That project went well, so I went ahead and did a CLA on the reflex viewing system of my early REX camera. However, the results were not as expected. Although the prism needed alignment, some of the lens surfaces had a very light permanent damage that was not easily removed. Still about 98% of what it probably was when new seeing as none of the optics in the viewfinder are coated. So, in the end, better alignment (I had noticed a few tilted horizons, attributed to the prism slightly askew), but the tiny bit of flare was still there. Of course this does not show on the film.
Maybe in another lifetime someone might try to polish the surfaces seeing as none of the surfaces are coated. Though, with such tiny optics, it would be so easy for the polishing to alter the refraction properties of the various elements and maybe make it harder to focus.

I had already done a CLA of the entire camera and the Non-Rex camera too. It was some time ago; before digital cameras were readily available and I don't have any written notes. As I recall, getting the two halfs of the inner frame together required like 4 hands, so I have not been too keen on doing it again. Though I wonder if I'm smarter now and it might be easier.

Very nice work, thank you for the comprehensive report