3Discover inter-ocular adjustments

[P3D Gabriel Jacob <jacob@xxxxxxxxxxxxxx>]

The real (I think it is.;-))Dr. George A. Themelis writes

>Note:  There are 2 positions in each lens but the different spacings are
>only 3, as follows:  Wide (both out), Medium (one out, one in, depending
>which one is out and which one is in this will shift the image but will 
>not change the spacing) and Short (both in).

Yes you are quite right. My mistake. There are 3 spacings as you mention.
I should have said 4 combinations.
 
>Now, I think (will have to double-check this) that only the short position
>matches the infinity separation of the images which is smaller than usual. 
>Use this setting for a child.  When adults use this setting then have a
>slight problem because their eyespacing is larger and the lenses are 
>rather small.

Yes the short position does seem to match the infinity separation of the 
images as you mention. In your previous post you surmise if the infinity
spacing is 55mm. I measured 58mm, so I guess close enough. The short
position on the 3Discover is 55mm. The next 2 wider positions are 60mm and
65mm. 

>Using the wide spacing will match the adult's eyespacing but now the
>lenses are not centered with the chips.  Hence the complains by Gabriel
>that he cannot see the entire frame.  Your best chances to see the entire
>frame is to use the small spacing and push your eyes closer together ;)
Again yes this is a problem with my viewing the images but is not the real
problem. I can solve this problem as I mentioned before and elaborate below
by adjusting the ocular position of the viewer in between the two preset
positions. Even with one eye and the lens centered over the image, I cannot
see the corners of the images. The reason is because the way the 3Discover 
is designed, one cannot bring the eyes close enough to the lenses. With a
VM viewer this is not a problem and you can bring your eyes right up to the
lenses. I can bring my right eye up to the left lens and then I do see the
whole image but cannot do that with both eyes due to the design.
 
>I believe most adults will chose the medium setting.  I am not sure where
>Gabriel drilled his third notch and why.

Yes again I agree to a point that most adults will chose the medium setting
,but the problem with that is, at the medium setting the lenses are not
centered over the images. At the medium setting, the lenses are either
postioned to the left of the images or to the right. This should pose no
problem I imagine if you can get your eyes close enough to the lenses, but
as I can't, I only see the left part of the image or right accordingly. So
therefore I found that by putting a third notch, I have the same ocular
spacing as the medium setting which is 60mm but the lenses are positioned
more to the center of the images. 
As to how it's done you might remember I mentioned this off line. Here is
the message for P3D.
>When you take out the cassette you can see where the interocular
adjustment snaps into the one of the two v shape slots. All you have to do
is dremel out another slot between them. Do the same with other lens. But
you don't have any problems with yours as you mention, so you won't have to
go thru the trouble. :-)<

>For the motor, I assume?  This is a fine portable viewer and a pair of AA
>batteries seems to be lasting for a long time.  Why would you want to
>immobilize yourself to save a few pennies?  And how many cassettes do you
>own that you use it so often yourself?  Once you looked at each a couple
>of times you are done.  Am I missing something?

Your right about the immoblization of the viewer with an adaptor. You don't
save that much but the purpose is when you don't have batteries lying 
around and another reason which I didn't mention because this feature is
not ready yet. So yes in effect you did miss something that I didn't
mention. What I didn't mention is that I am planning on putting a 6V
portable fluorescent lamp on the viewer. I have tried a 115mm fluorescent
tube which runs the full length of the cassette. I haven't built a mount to
unify the lamp housing to the viewer yet but holding it up to the viewer,
it works well. So this is the other reason for the adaptor.  

In a subsequent post you mention

>Wollensak lenses are fine for 7p but stretching if for 8p but so are the
>3Discover lenses.  At this point, and given the quality of the 3Discover
>images, I don't think a better pair of lenses would make sense in this
>viewer.  If you were to look at higher quality original images then we
>could discuss it.

The reason I asked if they could accommodate 7p or 8p is not necessarily
for the quality but rather on the interocular problem. If the lenses had
a large enough diameter that would have been a better solution. Also if
they were larger that would solve the other problem with the design 
limitation where you can't bring the eyes close enough to the lenses.

Sincerely yours
Gabriel, cut and dry, going to check out alt.shenanigans. ;-)





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