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mark22c
sage
Reged: 08/12/07
Posts: 343
Loc: cornwall UK
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high folks
i just bought two piars of those cheap bresser/meade 10x50 bins. allthough at first they seemed to be very good one pair had a distinct "fogging" in the prisms of both sides
after dissasembly and cleaning they're clear now, the problem i have now is they're not lined up. not sure how to explain it but here goes.
trough one ep while veiwing somthing long and strait ie a telegraph pole one side the view is tilted and the other not, obviously this makes collimation with the adjustment screws imposible
any help would be great with this especially if there is a technique to doing this that would make it easier 
thanks in advance mark
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opticron "imagic" BGA SE 8x42 roof's
10x42 roof's
meade/bresser (lidl) 10x50 porro's
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sftonkin
sage
Reged: 02/25/04
Posts: 395
Loc: Kent, UK
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If there is a tilt (usually called "lean"), then the prisms on that side are not mutually orthogonal. Specifically, the long edges of the hypotenuses of the prisms must be exactly perpendicular to each other.
Edit:
It may be useful for you to know that the angle of lean is double the angle of misalignment and opposite in sense. i.e if the image is rotated 10 deg clockwise, then the prisms are misaligned by 5 deg anticlockwise.
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Stephen
Hindsight: The only truly diffraction-limited system
Edited by sftonkin (08/27/07 04:42 AM)
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mark22c
sage
Reged: 08/12/07
Posts: 343
Loc: cornwall UK
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thanks steve at least i now know what its called, i did get it lined up useing the hit and miss method and managed to collimate them, ha ha... but now i have to clean the prisms on the other side seems they had somthing smeared on them or some kind of residue
just a thought maybe i could correct the "lean" without the ep's or main objectives fitted then fix with epoxy putty using an x marked out on a piece of graph paper to align
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opticron "imagic" BGA SE 8x42 roof's
10x42 roof's
meade/bresser (lidl) 10x50 porro's
Edited by mark22c (08/27/07 05:03 AM)
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mark22c
sage
Reged: 08/12/07
Posts: 343
Loc: cornwall UK
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i see what you mean, if you tilt or "lean" the prism 90 degrees the image moves 180 deg.
i supose that makes fine adjustment even harder. ha love it
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opticron "imagic" BGA SE 8x42 roof's
10x42 roof's
meade/bresser (lidl) 10x50 porro's
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Gordon Rayner
professor emeritus
Reged: 03/24/07
Posts: 506
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Try grid paper or Moire pairs(very sensitive). I have not yet tried Moire pairs, but just found a set. Next time I face a leaning situation, I intend to develop a method . Comparators help fix lean, but you will likely not think them worthwhile for a one-off situation. A low power weapon sight with cross hairs , focused on a target or target collimator with a similar line(s), with the prisms between the sight and the target, is another method. Verticalize the setup to let gravity help in positioning the moving prism. UV cured , or MS polymer, I prefer to epoxy, but all will work.
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mark22c
sage
Reged: 08/12/07
Posts: 343
Loc: cornwall UK
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thanks guys
i think i got it nailed, i dont think they're quite perfect but they're close enough to be comfortable.
after all this collimating, boy are my eyes are tired, i noticed that my revelation 25x100's are very slightly out of coll. had a look inside and there seems to be 3 adjustment points top and both sides in each tube that i can see, not sure wether these only adjust the one or both prisms at a time cant quite see how it works for the front ones.unless the plate holds both prisms and you move em together? any clue's
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opticron "imagic" BGA SE 8x42 roof's
10x42 roof's
meade/bresser (lidl) 10x50 porro's
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mark22c
sage
Reged: 08/12/07
Posts: 343
Loc: cornwall UK
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no its fine there spot on (the bressers i mean) after giving my eyes a rest.
still none the wiser with the revs though any help on that would be nice
thanks guys mark
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opticron "imagic" BGA SE 8x42 roof's
10x42 roof's
meade/bresser (lidl) 10x50 porro's
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