Large Field of View
No lens-based viewer can equal the human experience of seeing. The insurmountable obstacle is FIELD OF VISION. We see almost an entire hemisphere, although most of that is very low resolution. Compared to this 180 degrees, a viewing lens that maintains good sharpness can manage little more than 40 degrees. It is within this fundamental constraint that stereo viewers must exist, at least for the foreseeable future. The lenses used in the above viewer present an apparent field of vision of 35 degrees, equivalent to a 13" x 20" image at arms length. For comparison, the View Master image is about 11 degrees, or 5" x 6" at arms length - less than 1/10 the area.
The outstanding sharpness seen in this viewer is the result of a no-compromise policy throughout the chain: tripod if needed, good camera lenses, generally high depth of field , fine grain film, use of original slides (not dupes), and finally, good double achromat lenses on viewer. It is also critical, and designed into the viewer, that the slides are precisely orthogonal to the lens axes.
Bright, Even Illumination
This simple but crucial need has been well met by 25W "globe vanity" bulbs. The top surface has even brightness and is just big enough to cover a 35mm slide. A dimmer allows the output to be adjusted appropriately to the ambient lighting conditions.
Variable Inter Eye distance
Human eyes are often said to be 2 1/2" apart, but the actual value varies. The lenses on these viewers are adjustable to match any viewer's interpupillary distance. This ensures optimal lens sharpness and full image visibility.
Quick Access to Multiple Views
10-view magazines are used with this viewer (left above). Any 10 view cartidges can be attached to a magazine blank, and full magazines can be swapped in a few seconds.
Proper alignment of the 2 slides that constitute a stereo pair is crucial to viewer comfort. This issue is addressed by special tools and techniques for slide alignment and mounting (left) . Also crucial, is correct lens separation and good photographic technique. This viewer is designed for table top use, and the the entire structure tilts to best suit the viewer.
Protection of Content
Slides should never be touched or exposed to UV light, therefore in this system they reside in Gepe glass slide mounts. A pair of these mounts are epoxied onto a holding blank made of polycarbonate. The slides are further protected in the viewers plexiglass drum when being used. The viewing lenses are sufficiently recessed to avoid fingerprints. The entire viewer can by bolted down and its door locked , making a good system for public exhibition.