The Leitz Vario-Orthomat was a film based automatic camera system which included a camera head which attached to a microscope photoport plus a separate electronic controller which automated the exposure process. These cameras either with or without the controller appear from time to time on Ebay and Lab surplus websites. At the heart of the system is a rather interesting zoom photoeyepiece which is readily separated from the body of the camera and which can then be adapted to work with modern digital cameras.
The lower part of the eyepiece is designed to fit into a standard Leitz 38mm photoport. At the top it offers a rather unusual M45 screw thread where it originally screwed into the shutter/ exposure control part of the camera. The diameter of the upper optic of the eyepiece is 20mm, compared with 14mm on a standard Periplan GF eyepiece. As the accompanying picture shows, the film plane would have originally sat some considerable distance above the photoeyepiece. Reducing this distance significantly, affects the quality of the projected image rather little, considering how far outside its original design parameters it must be operating. To adapt the unit for digital camera use I had an M45 to standard T-thread adapter made so that I could mount a range of different cameras via appropriate T-thread adapters.
The barrel of the photoeyepiece incorporates a zoom mechanism which is calibrated with the range X5 to X12.5. The whole item is solid and heavy and gives the impression of high quality engineering. I have mounted four different cameras to this eyepiece mounted on the 38mm phototube of a Leitz Ortholux 1 with a trinocular head. Two Canon dSLRs the 400D and 40D via a T-thread to EOS chipped adapter and two zoom compacts, a Canon G9 and a Nikon 5100 via threaded adapter tubes. The Canon dSLRs showed only marginal vignetting at the lowest zoom setting of X5. The two compacts showed significant vignetting at all zoom settings as might be expected, and 75%-100% optical zoom was necessary on these cameras to remove the vignetting leading in some cases to undesirable increases in magnification of the subject.
Image quality is good, especially with the dSLRS. Chromatic aberration is generally well controlled with objectives of the same manufacturer and vintage as the eyepiece such as Leitz NPlans and NPlanfluotars. With other objectives including those of the Leitz Ultropak incident light system, chromatic aberration can be more noticeable, but not so as to make the eyepiece unusable. Parfocality between the camera and eyepiece image is not quite perfect, but only small focussing adjustment is necessary. It is possible this could be modified by placing some extension between the Vario-Orthomat and camera. Once set at a fixed zoom setting, focus is quite well maintained with Leitz NPL objectives in the range X6.3 to X40, but focus across the zoom range with a single objective is not so well maintained and some refocusing is necessary. It would be interesting to see how bellows mounting the camera and reproducing the designed 300mm or so distance between the top of the eyepiece and the film plane would affect these parameters, but I do not have the facilities to do this.
The biggest advantage of this eyepiece is it’s wide zoom range from ‘wide angle’ at X5 to ‘telephoto’ at X12.5 with little loss of resolution. As forumite Hindpool has illustrated this offers significant flexibility in framing subjects and zooming into objects of interest.
To increase its flexibility Leitz (as Leica) produced a X0.1 C-mount adapter to allow the Orthomat camera to be replaced by a video camera with retention of the widefield view at low zoom. I have seen some very good results from such a setup owned by a fellow microscopist.
The accompanying pictures illustrate the original camera (courtesy of Hindpool) and the eyepiece itself.
). So for a regular eyepiece, you have to have another lens system in the path to get a parfocal image. You change the scope focus to compensate, but as you point out, this is using the objective/eyepiece combination outside of its usual design focal condition, and brings in spherical and other aberrations, to some degree. A photoeyepiece is designed differently. I will try to find the prescription information for the 83 mm / 0.3X lens, and maybe play with the optics simulator. We should be able to make a similar lens combination with some commercially available lenses. The vario is such a useful eyepiece its worth a try.
