Re: [ATM] front surface mirrors for binoculars

["Stuart-ATM" <stuart-atm@earthlink.net>]

Dave,

I  have heard in other binocular(telescope) disussions that most eyes can
adjust up to 1/2 degree vertically and much more horizontally between left
and right images.  This is consistent with my experience using my 7x50s and
varying the interpupillary spacing.  But the eyes seem definitely more
relaxed for long periods when I get it as close as possible.

Suggestion:  Get a piece of reasonably flat substrate like 3/4 inch particle
board, MDF, or the white hard coated stuff.  It will be flat to much closer
than a fraction of a degree. Put it on a table, put your mirrors on it and
look through the binoculars.  Just see how it looks and feels, and whether
the image is deteriorated from normal up-viewing before you go the trouble
to build something.

If it works, then use a small piece of it to align both of your mirrors in
the same plane, and mount the assembly to your binocs.

Cheers,

Stuart

----- Original Message ----- 
From: "David Margrave" <david.margrave@gmail.com>
To: <atm@atmlist.net>
Sent: Saturday, March 04, 2006 3:45 PM
Subject: [ATM] front surface mirrors for binoculars


>I like binocular viewing but hate having my neck craned at abnormal angles.
> I know that one option is to get a reclining lawnchair and parallelogram
> binocular mount, but I was thinking of another scheme.  I got a couple
> front
> surface mirrors salvaged from overhead projectors.  I'm thinking that I'll
> make an arrangement to hold these mirrors in front of the objectives,
> rigidly at a 45 degree angle to the optical axis of the binos.  I'm
> envisioning something that could still be mounted on a normal tripod, sort
> of like a standard bino tripod mount with another 'leg' extending out
> infront of the objectives and holding the mirrors.   I'm comfortable with
> mechanical part of this (threaded mounts, etc).  No problem, as opposed to
> the optical aspects.
>
> I'm wondering about the variables and how critical they are?  IF the
> planes
> of the two front surface mirrors are not perfectly parallel is this going
> to
> work?  How much can the human brain accomodate to merge separate images
> that
> may be slightly off-axis?  Am I going to have to painstakingly ensure
> perfect parallelism, or make provisions for having one of the mirrors
> adjustable?   It would be nice to have just one large front surface mirror
> that would span both objectives, but I haven't come across one yet.  I
> know
> there are commercial products, but I am a  cheapskate and I'm trying not
> to
> spend real any money on this.
>
> thanks,
>
> dave
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