[photo-3d] Laser surgery for myopic stereoscopists ?!

["Abram Klooswyk" <abram.klooswyk@xxxxxx>]

When you are a stereoscopist and have a built-in stereoscope, 
obviously the most silly thing you can do is to have it surgically 
removed.

Actually, laser correction of  myopia _is_ removing a built-in 
stereoscope.
When you have a prescription of, say, 5 diopter negative glasses, 
taking them off has the same optical effect as using 5 diopter 
positive lenses by a "normal" sighted person (called emmetrope 
by the ophthalmic people).

The focal length of Holmes stereoscope lenses is about 20 cm
(8 inch), which _is_ 5 diopter (the diopter value of a lens is 
1 divided by its focal length in meter).

So when the separation of the homologues points of a 
stereopicture doesn't exceed his/her interpupillary distance too 
much, the 5 diopter myopic doesn't need lenses at all for 
stereoviewing (needless to say that vision can be better than 
with any lenses :-)). 

Unfortunately most vintage views have larger separations than 
most interpupillaries (except for example some tissues, some 
German about 1920s views and some French views), but learning a 
little divergence helps.

And what about reading glasses (getting of topic here) ?
After myopia surgery you need them from middle age, like all 
emmetropes, but as a mild myopic you don't. Putting your normal  
negative glasses at the point of your nose has the same effect as 
using (positive) reading glasses by emmetropes. (The "negative 
effect" get less moving the glasses from the eyes away - this can be 
optically proved, but just try it.)

If that doesn't work anymore, just take of your glasses and read 
at 20 cm (8") without any glasses, as my mother did until her death
at 
the age of 93.

And if you are NOT myopic? Consider laser surgery to become it.

Abram Klooswyk