ATM Re:Binocular Collimation

["Bill Cook" <atmj1@conceptsnet.com>]

There seems to be a bit more heat on the list lately. I hope my thoughts
will be taken in the spirit of trying to be helpful. I am assuming that
"Most regular binos" refers to binoculars rather than binocular telescopes.
Either way I feel my comments are sound.

Dwight Elvey Wrote:

>>>Collimating exit pupils only solves half of the bino collimation issue.
When the exit pupils are collimated, it only means that the illuminated
fields of view will be overlapped.<<<

If the fields overlap without the need for headache causing muscular
activity.the bino IS collimated. Correcting an error in collimation can be
made at the objective, prism, EP, or body (if it is a Zeiss style).
Collimation is collimation regardless of which convention - or combination
of conventions - is used. Please do not take this to mean that all methods
will have the same effect on aberrations WITHIN that collimated field. There
is a difference.

>>>Most regular binos also allow some tilting of the primaries to do the
final fusing of the images<<<

If this comment refers to binoculars, then I must say that in the many
thousands of instruments I have repaired and collimated, I have never seen
such an arrangement. On I have had to shim instruments of the Jason, Tasco,
Bushnell league. However, that was to move the whole lens laterally so as
not to induce coma or astigmatism.

(usually the primaries are wedged a little so that rotating will fine tune).
In a bino telescope, one can tolerate a little non-overlap of the fields as
long as the images fuse well.

This is true. But why would anyone want to cause eyestrain and headaches to
accomplish it? The image in each telescope should correspond for comfort. If
the edges of the field of view are not aligned, then you can only view a
single image in the center of the field by forcing the eyes, via the
muscles, to compensate. If I am missing something here, please let me know.

Just a thought.

William J. Cook, Opticalman Chief, USNR-Ret.
Manager, Precision Instruments & Optics, Captain's Nautical Supplies,
Seattle
Editor / Publisher, Amateur Telescope Making Journal
yata, yata, yata
www.atmjournal.com
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