Who give advice about stereo tailboard cameras?

[Steven Tribe]

My latest "final acquisition" is a tailboard german 13x18" reisekamera. Bought mainly for the universal iris mount that was attached. Underneath the grime was the delightful name Curt Bentzin Görlitz. I have just finished cleaning the brass and repairing the bellows when I noticed two central fixing slots in the back of the front standard (in the middle - top and bottom) and two matching slots at the back of the camera on the wood frame - just before the ground glass. These have obviously been there from day one as they are reinforced with brass.

I very much doubt wheither anyone here has the same camera - but this possibility for mounting a stereo adaptor may be common for other 5x7, 5x8 and 13x18cm tailboard plate cameras? Perhaps even the same system? I imagine that the front separating baffle must go quite deep into the bellows (length depending on lens image circle I suppose) - whilst the rear baffle can be quite a bit shorter. Or do they, perhaps overlap?

Any comments would be welcome.

[Ty G]

I am gonna hop in as an expert with stereo cameras. Yes, what you are saying about the slots in the front and the rear standards sound like they were for a middle "bellowed" septum. Most of the time, they were made just like the bellows. If it has the capabilities to do 5x7, 5x8, 4 1/2" x 6 1/2" then yes it most likely had stereo option. The only thing you didn't say was how big the lensboard is; as stereo cameras need a lensboard big enough (most of the time rectangle) to fit two lenses side by side usually at 3 1/2" or 4" apart depending upon the size of the plate.

[Steven Tribe]

Thanks for the info. I was afraid that stereo specialists had their own website somewhere else!

I enclose a few rough photographs. The total width of the "hole" on the lens board is 5". The slots have brass edges in towards the bellows so that it looks as is if there must have been compression in the central portion to keep it in place in use. The lens board is the slide across type - so perhaps it could use a single lens for landscape stereo photographs if there were accurate markings on the standard and board.

[Peter K]

The lens board is the slide across type - so perhaps it could use a single lens for landscape stereo photographs if there were accurate markings on the standard and board.

For stereo photographs the two optical axes - of the one or two lenses - should be only 65mm apart. So 5" is sufficient also for bigger lenses.

[Steven Tribe]

Thanks Peter. Curt Bentzin certainly knew how to make cameras - the brasswork details are tiny but wonderfully finished both front and back surfaces.

I forgot to mention that the brass reinforced cut out (one of four) can be seen in the 3rd photo.

[Steven Tribe]

Here is a very basic illustration of how I think the stereo accessory might have looked like! If would have been quite folded up when not mounted. The elasticated "ribbon" must be only be fixed to the folding edges - otherwise it won't contract and expand properly. Elasticated things don't last many decades so there not much chance of thesurvival of the genuine article.

[Ty G]

Peter, the 65mm measurement is important for the viewers, not the cameras. Yes, that number is supposed to be the average distance between eye centers, so this is important when making a stereo viewer. However, for the camera, distances can vary, depending upon the size of the plate. The more distance, the more stereo effect when viewed.

Steven, yes the sliding lensboard would allow a single lens to be used for the two sides of the plate (2 images). But, they weren't used for stereo images so much as they were used as multiplying cameras in a studio setting. If you have more than one person wanting an image or one person wanting more than one image, it is a lot easier and faster to process and expose one plate, then cut it in half.

[Peter K]

Ty, if the stereo pictures should have a "natural look" the distance between the lenses should have the same distance as the the eyes, 65mm. With bigger distances you will get an effect called "lilliputism", the subject appears nearer, and the relief is exaggerated. This was often used for table-top scenes etc. Also with "flat scenes" like arial images.

This is only valid for taking stereo-pairs with a "normal" focal-lenght, diameter of the image equal to focal-lengt. With longer taking-lenses the basis, normaly 65mm should be smallerto get the "natural look" too.

For big stereo-pictures, often used in photogrammetry, one needs a stereo-viewer equipped with mirrors or prisms to attanuate the long distances between the two centers of the two pictures to the eye-distance of 65mm.

[Steven Tribe]

As stereo lens sets are a pricey item (even the meniscus landscape sets), I'll think and try and use a single lens/sliding board system when the separation section has been constructed. The front standard has a lever release rather than a screw-in lock for the lens board. I do appreciate the response, Ty.

[Ty G]

You should have a blast and get very creative images. You can simply put a cardboard or wood solid septum attached to the rear standard. Make it so that when the camera is at min. focal length, the septum just comes short of touching the front. On the stereos I build, I do something similar using a solid septum about 4 1/2" long.