Collimating 1960's/1970's Asahi Pentax binos (1 Viewer)

[sssboa]

Hi,

So I have a few pairs now of those Asahi Pentax binoculars with yellow or gold tinted oculars. I had to clean 2 pairs inside. When you fit in the prisms they kind of fall into place, there's no options how to put them back. Then you brace them up with a piece of metal. Having put together everything I tried to align them. I turned the front lenses. There are 2 non-concentric/asymetrical rings around either glass. All to no avail. I don't even see the image getting considerably better no matter what I do.

As a contrast. I also did the same thing to Yashica binos from the same era. All those Japanese binoculars are constructed very similar like made in the same factory. Here too, the prisms fell into sockets and are kept in place with same braces. Then the turning of front glasses. Here there was one concentric/symmetrical ring around each lens, then one asymetrical/non-concentric. I turned the glass until the image converged into one. Success! So why not the Pentax binoculars, what's significantly different?

P.S. there are no collimating screws in these binos, not that class.
P.S. By turning the front glasses I really mean I mostly turned the non-concentric/asymetrical ring around the lens as I understand the lenses are the same and you differentiate between them by moving them within the sockets by moving the non-concentric rings?

Thanks for reading and appreciate any help,
Andy

 

[richard866945]

Hi,

So I have a few pairs now of those Asahi Pentax binoculars with yellow or gold tinted oculars. I had to clean 2 pairs inside. When you fit in the prisms they kind of fall into place, there's no options how to put them back. Then you brace them up with a piece of metal. Having put together everything I tried to align them. I turned the front lenses. There are 2 non-concentric/asymetrical rings around either glass. All to no avail. I don't even see the image getting considerably better no matter what I do.

As a contrast. I also did the same thing to Yashica binos from the same era. All those Japanese binoculars are constructed very similar like made in the same factory. Here too, the prisms fell into sockets and are kept in place with same braces. Then the turning of front glasses. Here there was one concentric/symmetrical ring around each lens, then one asymetrical/non-concentric. I turned the glass until the image converged into one. Success! So why not the Pentax binoculars, what's significantly different?

P.S. there are no collimating screws in these binos, not that class.
P.S. By turning the front glasses I really mean I mostly turned the non-concentric/asymetrical ring around the lens as I understand the lenses are the same and you differentiate between them by moving them within the sockets by moving the non-concentric rings?

Thanks for reading and appreciate any help,
Andy

Hello Andy
When you changed the positions of the rings, did the images move at all?
I suspect they might have but one or more of the prisms is/are out of place so I would check
they are all seated back correctly.
Regards Richard (the optical guy in The Repair Shop )

 

[sssboa]

Yeah, you're probably right. There is no much wriggling space though for the prisms. They just fall into place, a plastic niche and are clamped down with springy metal straps.

 

[Patudo]

It might be worth your obtaining one of the books authored by one of this forum's most prominent members. He is/was an experienced optics technician and collimation is a regular topic in his posts. If you do, please keep us updated with your progress.

 

[sssboa]

It might be worth your obtaining one of the books authored by one of this forum's most prominent members. He is/was an experienced optics technician and collimation is a regular topic in his posts. If you do, please keep us updated with your progress.

I have bought "Porro Prism Binoculars Overhaul" and "A Concise Guide to Collimating and Restoring Vintage Binoculars", both by Alberto Roberts. You meant this author?