Quote:
Originally Posted by Roger Davis
Firstly there are two types of collimation. One is "Conditional Collimation" the other is "tail of arc".
The first is as it sounds, it is conditional in the fact that it good for the person who has done the collimation and is only good for the one interpupilary distance.
The second is a bit harder to do, but not overly so. Assuming that the prisms have been made orthogonal, it requires the alignment of the central hinge to the right or left hand side. This can be done using an auxiliary telescope of about 4X mag that has a rhomboidal prism over the objective that enables a view over the top of the binocular at the same time as looking through the binocular at an infinite target. Viewing through that side adjustments can be made to the eccentric ring to eliminate parallex error. Once one side has been done, then the rotation of the other side's eccentric to bring the image coincident can be done. This enables the use of the binocular by a wide range of interpupilary distances.
For the collimating device you can use an 200mm Newtonian or SCT telescope in reverse with an illuminated crosshair in the eyepiece. This will of course provide you with an infinite target with the light rays being parallel. All you have to do is make a rhomboidal prism! :-)
I recommend two books on this, one is Basic Optics and Optical Instruments SBN 486-22291-8 or Understandig and Attaining 3-Axis Binocular Collimation by my mate William Cook ISBN 9781790983780 (Editor for the no longer published Amateur Telescope Making Journal [for which I was a contributing editor])
Or you can wait until I finish writing my book, which will be a while yet before being published.
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Hi Roger ,
Thanks for the excellent advice !
Shame your book is not yet for sale
I have had some luck just resetting the front objective but know this is not good enough , I do admit to stuffing up sets & thus have left them for the future if I ever know what I'm doing
I've even mucked up some just trying to do an internal clean , even lost those tiny grub screws .
Checked out a Rhomboidal prism you mentioned ( used to shift an incident beam without angular deviation or orientation change ) don't have one yet .
Maybe it would be better to just pay an expert ? What do you think please
Best Regards
Bobby .