Re: making my own telescope type magnifiers?
- From: vj@xxxxxxxxxxxxxxxxxxxxxxx
- Date: Wed, 09 Aug 2006 11:42:18 +0100
On Tue, 08 Aug 2006 07:59:33 -0700, Eric R Snow
<etpm@xxxxxxxxxxx> wrote:
I've been looking to buy head worn telescope type magnifiers because
the Opti-Visor and their ilk all bug my eyes. The optometrist said
this is because of two reasons in my case. First is that they don't
correct my astigmatism and second because the spacing of the lenses
doesn't match the spacing of my eyes. The least expensive of the head
worn magnifiers I have found so far is close to $400.00 US. And there
appears to be no upper limit in price. So, I'm thinking that by using
the Edmunds book "Popular Optics" for the math and design ideas, and
buying surplus coated lenses I can make my own. Any suggestions?
Thanks,
Eric R Snow
A bit heavy for eye worn but take the smallest pair of prism
binoculars that you can find. Remove one object glass (the big
front lens) carefully noting which is the inside side.
Mount this lens just in front but not touching the other
object glass. What was the inside face of this extra lens should
this time face outwards.
You've now got a well corrected telescopic magnifier. The
two object glasses make a 1:1 image at the eyepiece focal plane.
The magnification will depend on the eyepiece fitted - usually
about 10:1. The working distance depends on the size of the
parent binocular - about 3" for a small binocular, about 7" for a
larger one.
You can do the same trick with opera glasses but the
magnification will be low and the field of view small.
Jim
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