The brilliant box camera: Zeiss Ikon Box Tengor

The last thing missing in my collection of film camera's was a box camera. I was lucky enough to get this beauty for free. It is a Box Tengor made by Zeiss Ikon. According to the camerapedia, my camera is the 55/2 version, one of the latest.

It's actually pretty advanced, featuring a shutter interlock and a lock button to avoid accidental exposure when the shutter is armed. Actually, I lost 1 frame on my testfilm because I was pushing in the shutter release very slowly. Halfway through, I changed my mind and did let go of the shutter release to reframe the image, but the interlock had already engaged. The consequence was that I could't release the shutter anymore without winding on the film. My mistake.

The lens only has 1 element. I managed to clean it by keeping the shutter open with the bulb switch. When you want to focus closer, there are 2 auxiliary lenses which can be pulled into place: one should focus between 2 and 8 meters, the other one between 1 and 2 meters.

In the picture below the focus setting was 2-8 meters and the front wheel of the motorcycle was at a distance of 3 meters. The f11 diaphragm didn't give enough DOF. Only the front of the front tyre is in focus.

The picture below was also taken at the 2-8m setting, with the window at approximately 4 meters away. The f16 diaphragm gave more DOF this time, but the focal distance seems to be somewhere around 2.5 to 3 meters instead of 4 meters (=hyperfocal distance if DOF from 2 to 8 meters is to be achieved).

The 1-2 meter setting shows a similar result. The picture below was taken at f16 with the headlight at 1.5 meters from the camera. It is already slightly unsharp. The front shock absorber is still in focus, so I guess the real focal distance will be around 1m20.

The best image quality is clearly achieved without the auxiliary lenses, at the infinity setting. The picture below is taken at f16.

The camera is giving a pretty sharp image, but only in the center. Towards the edges there is quite some light falloff and a bit of unsharpness. In the image below I moved the diaphragm to f22. This increases the DOF (obviously) but it seems to give slightly less sharpness and contrast at infinity. Probably this is due to diffraction kicking in.

At f11 the image deterioration towards the edges is much more severe. Note that the image below was also taken with a yellow filter, causing a weird flare issue at the top.

I also tried to provoke lens flare by including the sun in the frame, but nothing happend. I guess flare is more of an issue with lenses with multiple elements.

I love the simplicity of this camera. It's a great experience to use one. The mirror-and-lens reflective viewfinders seem impossible to use in indoor lighting, but they are quite usable outside. The best results are achieved at f16 and infinity, although subjects can also be positioned at 1m20 or 3 meters. If you open up to f11, be prepared to use the edge unsharpness as a creative tool. f22 gives you more 'normal' images without too much darkening or unsharpness in the corners.

The shutter speed of the camera is fixed at 1/25th of a second. I measured my shutter at 33ms, so this is a more convenient 1/30th of a second.

High-res 40 Mb images are available in this Google Plus album.