Have just been handed a pair of old 8x30 Jenoptems with serious double image. Having correcded this on the front concentric rings I find that I have a twisted image. the l/h eye is very slightly clockwise and r/h eye is way out anticlockwise. They are in very good condition with no aparent damage from being droped. The twist was there before I adjusted the double image. Any help from you experienced guys woul be appreceated.
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Twisted image (1 Viewer)
- Thread starter hebog
- Start date
Otto McDiesel
Well-known member
uh, take them to a repair shop?
solentbirder
Well-known member
hebog said:
Sounds like the prisms need to be adjusted. In my experience this is tricky for a non-professional to fix.
Otto McDiesel
Well-known member
hebog said:
From what you describe, it sounds like they are worth 0.99, but i understand.
Don't move the 4 prisms, you'll never put them back properly. Maybe turn that thing into two monoculars of sorts?
henry link
Well-known member
This condition is called "lean" or rotational error. It happens when the long axes of the two halves of the Porro cluster are not at a perfect 90 degree angle. Possibly the prisms were jarred loose at some point. Fixing it requires removing the eyepieces and objectives. Presumably at least one part of the prism cluster will have come unglued so that only the metal strap is holding it in place. The prisms need to be repositioned by sighting a reference vertical like the edge of a door through the prisms. Then the cluster needs to be reglued with epoxy. You'll then need to recollimate the objectives. Piece of cake. 
)
)Like you said a piece of cake, will have 6 or 7 beers before I start, will go and get the hamer and chisel right now.henry link said:This condition is called "lean" or rotational error. It happens when the long axes of the two halves of the Porro cluster are not at a perfect 90 degree angle. Possibly the prisms were jarred loose at some point. Fixing it requires removing the eyepieces and objectives. Presumably at least one part of the prism cluster will have come unglued so that only the metal strap is holding it in place. The prisms need to be repositioned by sighting a reference vertical like the edge of a door through the prisms. Then the cluster needs to be reglued with epoxy. You'll then need to recollimate the objectives. Piece of cake.
