Geoscope Standard mirror stereoscope
The Geoscope Standard model is a mirror stereoscope for viewing side-by-side prints in the parallel format such as aerial photographs and supports images separated by around 9 inches. A 1.2x magnification eyepiece is included and when viewing through this eyepiece the coverage is around 8 inches high and up to 5.9 inches wide which covers the full 60% overlap of aerial photographs. The Geoscope features chrome plated first surface glass mirrors that present very clear images without ghost reflections or chromatic aberration (color fringing). The mirrors are set at a fixed angle around 46 degrees and are parallel. The Geoscope has a clever folding design in which the large mirrors rotate and fold into the body of the viewer for compact storage in the supplied plastic carry case. A parallax wedge is also included along with instructions on its use. The viewer is made from tough and durable ABS plastic.
Geoscope Standard StereoScope
The Geoscope Standard model by Stereo Aids in Australia has a relatively wide separation between the mirrors making it suitable for viewing images with a separation of between 8.25 to 10.25 inches and thus supports images up to 10.25 inches wide and is also a good viewer for smaller images so long as the left and right halves can be separated. High quality first surface chrome mirrors are used that provide crystal clear images. The coverage is an impressive 8 inches high. The coverage width is up to 5.9 inches when viewed through the magnifying eyepiece. The coverage width does decrease when the eyes are further back from the lenses and mirrors and for the widest view the eyes should be placed close to the eyepiece and mirrors. If you are wearing glasses then your eyes may be a little further back and the coverage width will decrease a little. With the magnifying lenses the eyes need to focus from around 2 meters to infinity, so people who are short sighted may need to wear corrective glasses. The Geoscope Standard does not have an adjustment for eye separation but the separation of the images being viewed can often be varied to compensate and in this case the Geoscope maintains a respectable coverage width over a wide range of eye separation from 55mm to 75mm - please see our coverage tests of the Geoscope for more information. This coverage makes the Geoscope ideal for the inspection of large images and it is possible to pan the viewer around to inspect the wider image. A 1.2x magnification eyepiece is included with the Geoscope Standard model, and a 3x magnification binocular eyepiece is included with the Geoscope Pro models. The Geoscope does not include baffles to block secondary images, and with a little experience you can learn to ignore them, but if you are presenting stereoscopic photographs to novices then it may help to add baffles to the Geoscope. The Geoscope has a compact design and is supplied in a convenient and relatively small 360x220x65mm carry case made from tough and durable ABS plastic.
The carry case is held closed by a latch built into the case. The latch itself does not move and the case is opened by pushing the top and bottom halves of the case inwards slightly, twisting the case and clearing the latch. There are 'PUSH' signs on the edge of the case.
The Geoscope has a clever folding design in which the large outer mirrors rotate and slide inwards for storage.
The large outer mirrors are unpacked by firstly sliding them outwards and then rotating them into position. The mirrors a packed by reversing this operation, rotating them and then sliding them inwards - note that the mirrors slide in independent slots at different heights.
The outer mirrors are held in position by the weight of the stereoscope and they rest on seats built into the body. The legs should rest on a flat surface to prevent the body twisting and causing misalignment of the mirrors. The design works well for its intended purpose of viewing prints on a flat surface.
With some care it is possible to lift the stereoscope and even tilt it to view a vertical monitor or print, however it was not designed for this and the mirrors will swing out of position unless held and the body is not rigid enough to maintain good alignment of the mirrors when not sitting on a flat surface - and also take care not to tilt the Geoscope with the eyepiece installed as it will fall off and may be damaged.
For a good field of view it is necessary for the eyes to be close to the first mirrors and the body has a hole to fit the nose enabling the eyes to be very close and the body is open for ventilation. The Geoscope may be used without the eyepiece installed but the first mirrors are exposed and can become dirty from the touch of the face and the oil can be hard to clean off.
A 1.2x magnification eyepiece is included with the Geoscope Standard model. The eyepiece fits into four small holes in the stereoscope, and while this prevents the eyepiece sliding horizontally it is held in purely by its own weight and will fall out if the stereoscope is tilted. There appear to be other mounting holes and these may be designed for use with 3X binocular eyepiece included in the Geoscope Pro model. The optical path length is around 11.2 inches and the eyes need to focus in the distance with these lenses - rough testing suggests the eyes are focused at a distance from around 1 to 2 meters to infinity when using this eyepiece.
A parallax wedge is included along with instructions for using it. The back came with a protective plastic cover which although scratched is intended to be removed before use.
