Kuribayashi 35mm f3.5 Lens

[colinbm]

Yes, I would be very careful if I were to open a Kyoei or Kuri 35mm.

[dabateman]

Colin, the main question I have about the Kyoei/Kuri 35mm elements, pertains to the second element from the front, the element that is domed on both sides.

The element looks like it has identical domes, like you could reverse its direction and it would work the same either way, but will it or not? Is that element the same if it is installed in reverse?

Because unless you are extremely careful, you will loose track of which way it was installed if you take it out. Even with close examination, I see no difference in the front and back of that element.

Something to remember or investigate if you take the lens apart...

 

Cadmium,

It will "work" in that you can put it back together. But you will have changed the optical formula and you will get a non designed effect. This could be closer focusing distance, or odd light bubbles on the sides, or beyond infinity focus. Many different things could happen.

You can do the same with a Wollensak 25mm f1.5 lens, some of the elements will fit in either orientation.

When I made a S-mount (m12) lens to work for UV, I changed the element spacing and flipped one element to gain larger back focusing distance. These are super cheap web camera lenses. But you have to be careful with mount adapters for M12 lenses. As my new to me Olympus Em5mk2 has slightly closer dust shaking filter and I scratched the surface slightly. It hasn't affected anything yet, but now I don't both with the 3.6mm f2.5 M12 lens I made. Its not worth the camera damage.

 

[Cadmium]

Perhaps, but the questions is IF the element is the same in both directions, because both sides look identical, so they may be, but I can't say for sure.

 

The element in question is called a biconvex element.

 

Here is an illustration of a typical retrofocus wide angle lens, which looks very similar to the design of the Kyoei/Kuri 35mm lens.

https://en.wikipedia...e:Angenieux.png

 

In this illustration the second element from the front has the double domed design (like I show in my drawing), except it is not the same dome curve on each side.

This doesn't mean that the one in the Kyoei/Kuri 35mm is not the same done on each. I see no difference in either side, but that doesn't mean there isn't any difference.

It could be the same either way, or not.