Some Information about Dimensions

Many decades ago ANSI (American National Standard Institute) established dimension standards for double film holders of the lock-rib type. The sizes covered are 2X3, 3X4, 4X5, 5X7, 8X10, 11X14 and 14X17. This gave film holder manufacturers and camera manufacturers the critical dimensions needed to insure compatibility. Unfortunately ANSI standards were never adopted for any of the banquet and panoramic cameras in sizes such as 5X12, 7X11, 7X17, 12X20, nor for a number of other sizes such as 16X20 and 20X24. The result was that the manufacturers of cameras, such as Deardorff, Folmer & Schwing, Korona, and B&J, built cameras and holders to their own standard without regard to the dimensions of other camera manufacturers. This means that the holders of one company will often not fit a camera manufactured by another. In fact, one observes significant size difference even in Korona backs and holders, both in terms of width and in the position of the rib-lock. In some cases the differences are relatively small and adaptation of one brand holder to another camera is sometimes possible. F&S cameras, for example, can easily be adapted d to take Korona type holders, though the reverse is not true.

As we know the manufacture of banquet and panoramic cameras ceased in the 1940s and these type cameras fell out of use for several decades. In the late 1970s and early 1980s banquet and panoramic cameras, especially the 7X17, 8X20 and 12X20 formats, were resurrected because of the emerging popularity of palladium and platinum printing, which of course requires a same size negative for contact printing. Since many of the existing holders were in poor condition, and hard to come by, a few companies began restoring and building new holders. Most of the new holders were built to Korona standard, based on an existing model. Unfortunately, since there was considerable difference in dimensions between the existing models of Korona backs and holders, new ULF holders were not built to any common standard, and that fact continues until this day.

What this means is that unless you have a thorough understanding of the issues involved in a good holder to camera back fit you should seek advice from someone with expertise in the use of ULF equipment before purchasing ULF holders for a given camera. In most cases it is possible to adapt either the holder or the camera for a good fit. Adapting the camera back is usually the best course of action since it involves only one change for all holders.

The following considerations are offered to give some idea of the major issues involved. There are five critical measurements.

A. Width of loading end flap. The loading end flap is the part that you lift to load the film.
B. Distance from end of holder at the flap end to the "beginning" of the rib-lock. This distance is measured from the very end of the holder to the "beginning" of the raised rib-lock.
C. Width of holder. This measurement is taken across the short dimension of the film holder. It determines if the holder can be inserted into the camera back.
D. Width of rib-lock. This distance determines how wide the routed groove in the camera back needs to be for the rib-lock on the camera to fit into it and form a light baffle at the side of the holder where the film is inserted.
T. Distance from septum to outside of frame. This distance should equal ground glass displacement minus the width of the film. This distance varies on holders of different make from a minimum of about 0.030" to a maximum of about 0.060". On S&S holders the T-dimension is 0.035" on the 14X17" holders and 0.350" on all other sizes.

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