Konica Domirex (1963)

To the best of my knowledge, the Domirex if the only leaf-shutter SLR Konica ever made. Many makers made leaf-shutter SLRs in the early 1960s, but what made the Domirex something of an oddity is that it had no movable mirror. Instead, it had two small fixed mirrors placed at a 45º angle in front of the shutter. They deflected light upwards to the viewfinder thanks to a prism situated above the lens barrel. 

Early version of the Domirex with a selenium light meter, showing the shutter speed dial and the
meter readout on the top deck and the aperture dial with the AE setting on the front of the body.
Photo: Kamera Rebyu: Kurashikku Kamera Senka, No. 10, Sept. 1987, p. 13. (M)

Since the little mirrors were installed in front of the shutter, the prism was placed on top of the lens, in front of the camera body proper, something that gives the camera an appearance different from all other cameras. The mirrors deflected about 20% of the light penetrating into the lens towards the prism, while the remainder was used to expose the film.

The idea behind this arrangement was the elimination of the swinging mirror and, thus, of the vibrations proper to SLR cameras. Another advantage was the possibility of observing the scene while the picture was being taken.

This system had a couple of serious drawbacks, however: As the viewfinder only showed 20% of the light entering the lens, focusing was rather difficult. This is an issue which Canon had to deal with as well with its Pellix model, also released in 1963. Also, the camera’s two small round fixed mirrors caused serious vignetting issues. Ten little reflective dots were added around each of the small mirrors to help alleviate the situation, but they failed to resolve the problem and often caused images characterized by doughnut-shaped blurred areas in the corners.

Later version of the Domirex with a CdS light meter, shown here with a dedicated wide angle converter.
Photo: Kamera Rebyu: Kurashikku Kamera Senka, No. 10, Sept. 1987, p. 82. (M)

The Domirex was a fixed-lens SLR and this lens was a Hexanon 57/f2.4, made of 4 elements in 4 groups, with a minimum focusing distance of 1m. A wide and tele-converter were also produced for use with the Domirex. One occasionally hears speculations that Konica may also have made a version of the Domirex with interchangeable lenses using the Konica F mount. Given the placement of the mirror and film to flange issues, I suspect such rumors are unwarranted.

The shutter on this camera was made by Seiko. It had only four speeds – 1/30, 1/60, 1/125, and 1/250, plus the B setting. The Domirex had shutter-priority based automatic exposure relying, initially, on a selenium cell, but some of the last versions of the camera were provided with a Cds cell. The camera’s metering range was 5.7 to 17 EV with film speed settings going from ISO 6 to 400. The viewfinder had 1:1 magnification ratio with the lens set at infinity and automatic parallax correction. The camera weighed 790g.

Although the prototype was announced, perhaps a bit hastily, at the 1963 Photokina, in the end the camera was not marketed. This was largely due to the company’s failure to resolve the camera’s vignetting and dark viewfinder problems.

I obtained much of the above information in December 2007 from Henry Froehlich, who also told me Konica had lent him one of the prototypes of the Domirex so he could try it out and gather feedback from American photo industry leaders. He in turn lent it to one of the most famous photo equipment reviewers at the time and while that person had it, the prototype was stolen and never seen again.