One big difference between porro and roof prisms. Roof prism systems must include a phase correction coating.
So inexpensive porros will always give a better image compared with inexpensive roof prism systems that
don't have phase correction.
Yes, those little pieces of rubber 'o' ring material are what gives the friction.
I have about 30 different sizes in my workshop as the smallest difference in diameter.
will mean the eyecups are too loose or jam. If you can accurately measure one of
the existing pieces , I will see if I have...
Your binocular was made in 1979 and was a close copy of the C Zeiss Jena Jenoptem 8x30. Many parts are interchangeable especially the prisms.
The covers were sealed with a heavy black wax and the gaps around the eyepieces were fitted with greased green felt so they are virtually
water proof and...
Maybe you don't realise that the front lenses are in eccentric rings.
Having got the prisms roughly in place, you can unscrew the covers around the lenses; release the lock ring
and rotate the eccentric ring and or the mount that contains the object glass.
It's not quite that straight forward...
Definitely 7x50. The eyepieces were fixed focus but could be altered by a technician if required. However as the young fit men
who used these, had 20/20 vision, they are rarely changed form the factory set up.
The repair was carried out over 4 days as I kept having to wait for my turn with the...
with patience and practice it is possible to get perfect alignment without a collimator.
I am however pleasantly surprised when I adjust a binocular using a distant object
and find the alignment is absolutely correct when checked on a collimator.
It's only taken about 57 years.
As you are not so very far away, do you fancy bringing your binocular to my workshop and using one of my collimators?
I'm on the outskirts of Hythe, Southampton. I'm around this coming week then off for a break.
You can see me and my portable collimator on The Repair Shop on Tuesday at 4.30...