[photo-3d] On achromatic stereoscopes....

["Dr. George A. Themelis" <drt-3d@xxxxxxx>]

Boris writes:

>Now that I have started making more cards, there is another thing that I've
>discovered that I don't like about (print) cards.  But this will be related
>to the quality of my viewer, and to color prints only.  Members of this
>list, please enlighten me if this is a problem with all viewers:

All non-achromatic viewers, which is the vast majority of
viewers.

>Of course it serves me right.  I should be shooting for and making images
>for the "classic" format in B+W, right, Bill?   The effect does not appear
>in B+W views, naturally, even though chromatic aberration may be apparent
>along contrasty edges.

Chromatic aberration is present in B&W images and it is
equally irritating for me because you see colors where
you are not supposed to see colors.

>Is this problem solved in the so-called achromatic lorgnette?

Yes, and also with the achromatic Visual Survey Telebinocular
viewers.  (I have a dozen of them for sale BTW :))  For more
information on these viewers, please see here:

http://home.att.net/~drt-3d/toys/KeystoneVS/index.htm

Here is what I wrote in photo-3d when I got one of these
viewers:

"I remember how I got my first Keystone Visual Survey 
stereoscope. A friend from photo-3d, M. S., offered to 
sell me this stereoscope for a little over $100. I 
accepted but felt that I was doing him a favor and 
wasting my money because I already had some very nice 
stereoscopes at home. Perhaps I could sell it and break 
even, I thought. The stereoscope arrived, I opened the 
box and took a look. "Ugly duck" was my first thought. 
I decided to give it a try. Grabbed a few stereo views 
and took a look. 

Wait!!! Just a minute!!! What is going on here??? There 
is something in the quality of the image that I have not 
seen before. Are my eyes being fooled? I run into the 
basement and pulled out all my stereoscopes. I checked 
the same view with every stereoscope I owned, plus the 
Visual Survey. No, my eyes were not being fooled. The 
image through the VS looked better than anything else!!! 
No sign of chromatic aberration (I could see false colors 
in every other scope I tried). Sharper images. More details, 
especially at infinity. Easier to my eyes. I could be 
viewing for hours with no fatigue.

WOW! This baby is here to stay! I gave it a good TLC cleaning 
and have it in my basement ever since. Whenever I want to 
enjoy stereo views, this is the scope I use. Later, from 
discussions in photo-3d and input from Alan Lewis, I 
realized the secret behind the optical quality of this 
instrument: It has achromatic lenses! While every other 
scope has simple wedge lenses, this baby has achromatic 
lenses. I know from my slide viewer experience what 
difference achromatic lenses can make. The large size of 
the lenses and large FL makes this difference lens 
significant, but it is still there. And a trained eye 
can pick it up very easily.

The bottom line: I sold all my other stereoscopes and kept 
this one. I bought another (smaller) stereoscope with 
achromatic lenses from Alan Lewis. And now I actively 
search, buy and sell these Keystone Visual Survey 
Stereoscopes. "

Another testimony:  I recently interviewed a club member
who has done a lot of work in stereo views. He told me
that when he got his Keystone Visual Survey viewer he
stayed up all night long looking at his stereo views.
It was like he is seeing them for the first time.
"Wow!  Look at this one!  Wow!  Looks how BAD this one
is!"

So, Boris, it looks like you NEED an achromatic stereoscope!

George Themelis