Lens specifications:
36 mm dia x 82 mm focal length coated achromats
Edmund Scientific #E44,075 (about $35 US each)
Focus adjustment:
fixed at infinity
Interocular adjustment:
fixed at 66 mm
Type of illumination:
Diffuser at rear for ambient light or can attach light box which has two 2.5V@0.8A frosted
halogen bulbs. Light box powered by external 4 C-cell nicad pack.
Materials:
Milled hard maple side pieces and 3/16" 5 ply plywood for top and bottom. White 2mm
thick plexiglas diffuser and rubber grommet lens holders.
Formats supported:
Slides in King Inn format mounts only. (80 mm high x 132 mm wide)
Description of viewer:
I wanted to build a viewer that was as small as possible to be easy to hold. The removable
light box allows me to use the viewer alone with sunlight outdoors or to have a smaller
package to take along with me. The battery pack connected via 18 ga speaker wire keeps the
weight of the viewer down.
The left photo shows the viewer with light box attached and a slide installed (difficult to see). The Pentax soft lens case contains 4 C-cell nicads which power the two halogen bulbs.
The right photo shows the viewer with top removed and light box tipped upwards. You can see the black light block in front of the slide and the center divider and other surfaces covered with the black flocked paper (sold by Edmund Scientific). The plexiglas diffuser is visible at the rear. It is far enough away from the slide that dust specks on it are well out of focus.
The light box has two bulbs on holders centered behind each film chip for very even lighting. Visible on the bottom is a setdown switch that extends battery life whenever the viewer is placed on a flat surface. It is held on by the brass screws that are visible.
Construction comments:
This prototype viewer was my first router project. I used the router to make grooves to
hold the plexiglas, slide and light block. Also used it to make the shoulders that the
plywood fits in and to round over the outside corners of the maple.
The viewer was originally made for different lenses (glass magnifiers). When I got the achromats I made a new front that holds them in place with rubber grommets. The new front is shimmed into the right place (for focus at infinity) with rubber washers at the four corners.
Future plans:
I plan to build a final viewer that has focusing and possibly adjustable interocular
spacing. I will probably retain the thick sides plus plywood top and bottom construction
method.
I also plan to retain the removable light box idea. I plan on having it attached by rare earth magnets for quick removal and attachment.
The final one will get some stain and varnish. I promise :)
Are these viewers for sale?:
No
Availability of plans:
No. More details available via email.
Please visit my website at http://www.angelfire.com/ca/erker/
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