In short - Pentax 5.5x SMC 4-element viewing loupes...

The diameter of this giant chunk of glass almost stretches a 6x6 area.

They're made for comfortable viewing of full frame 35mm slides with incredible eye relief. A Realist slide can be practically, and proportionately, viewed in stereo inches away from the lens! While they're rated as 5.5x, I found that the virtual size of a 5p stereo realist image is no larger than that in my Kodaslide II viewer

My 100 asa Spuddy slides look intense and totally grainless thru these thangs. You can only see the side borders if you look hard enough. Yeah, it pincushions, but it also has that unbelievable eye relief So interior & architectural subjects will suffer proportionately to the extent you "immerse" you face into the glass. Organic stuff is not so noticeable.

The hold-up for me is heavy aluminum base for the fine-threaded lens. When I put my pair together, the width of these barrels make the interocular wider than the stereo pair centers! Actually, the rubber-rims of ocular ends need to be brought closer - practically "kissing" - to get the right spacing. But, they can't screw free from the bases. I suspect it is the thin, bottom retaining ring that holds them (and the bottom lens?) in. But the rings notches are too small for my spindly spanner wrench to really try it successfully.

John - if you - or another handy, established name on this list, wants to try and free these lens and test my pair in a prototype viewer, let me hear from you. They're so wide and heavy, I don't think the thin, narrow, plastic 3D World viewer could brace them. I think the most practical solution might be an alternate Saturn Viewer lens box.

http://www.bhphotovideo.com/c/product/158272-REG/Pentax_60051.html#specifications

Format
35mm

Magnification
5x

Lens Construction
4 elements, 4 groups

Linear Field of View
Not specified

Dioptric Correction Range
Not specified

Eyepiece
40mm; Aperture: 49mm

Dimensions
Outside Diameter: 67mm (2.6"); Height: 75mm (3")

Weight
320g (11.4 oz)

lattie_smart wrote:

> In short - Pentax 5.5x SMC 4-element viewing loupes...
>
> The diameter of this giant chunk of glass almost stretches
> a 6x6 area.

- snip -

> The hold-up for me is heavy aluminum base for the
> fine-threaded lens. When I put my pair together, the width
> of these barrels make the interocular wider than the
> stereo pair centers! Actually, the rubber-rims of ocular
> ends need to be brought closer - practically "kissing" -
> to get the right spacing. But, they can't screw free from
> the bases. I suspect it is the thin, bottom retaining ring
> that holds them (and the bottom lens?) in. But the rings
> notches are too small for my spindly spanner wrench to
> really try it successfully.

For cases such as this, I suggest going to the hardware or
paint store. Find a _stiff_ putty-knife or paint scraper of
about the right width to span your lens. Then take it home
and attack it with a hacksaw (to shorten it and make it
stiffer). Once it's down to an acceptable length, hit it with
a file and a grinder to bring it down the correct width and
relieve it to clear the glass. For somewhere less than $10,
you can often make the perfect tool for the job.

Another option, if you think it may fit, is to ask someone
(hint, hint) for the loan of a beefier spanner:
http://www.skgrimes.com/span/index.htm

> John - if you - or another handy, established name on this
> list, wants to try and free these lens and test my pair in
> a prototype viewer, let me hear from you. . . .

Thanks for thinking of me, Lattie, but I've got so many
projects in front of me that any attempt to add another would
simply push something off the table and on to the floor.

________________________________________
John Thurston
Juneau, Alaska
http://stereo.thurstons.us