Edward A. Hoover © 2002 for largeformatphotography.info
As my interest in photography and large format in particular has evolved, I have become aware of several things about the hobby in general that have led me down the path of simplified large format camera design. My initial interest was aroused by the incredible detail that is visible in the photographs taken by many of the pioneering photographers from earlier eras. After a number of years of casual observation I decided to see what design features these earlier cameras had in common with there modern counterparts and began to collect available examples of various types such as the folding view, tailboard, box and early large roll cameras.
The first thing that became apparent was the high price of collecting usable samples and secondly the rather advanced stage of deterioration that was common to the frames and bellows of these cameras. I then began a quest for information on early fabrication and manufacturing techniques. The information that I found consisted almost entirely of repairing them and very little about design or building them so I began to develop my own methods of construction based on readily available materials and low tech tooling that most craftsman are likely to have available to them or own personally.
The bellows being the most commonly dilapidated item I concentrated my efforts in this direction first. All techniques for fabrication that I could locate involved the rather imprecise method of adhering the ribs or stiffeners directly to the pre-cut covering with little or no method of precise control of intersecting dimensions or angles. After dissecting various models, I developed the method of temporarily adhering the stiffeners to a precise layout and then transferring them to a precision matching form wrapped in the base or inside layer of the covering. After application of the outside layer of the covering the bellows is then slipped off of the form and the end rings are fixed in place. With this simple method I was able to design and complete a bellows with no error in very little time.
I next focused my efforts on the camera back and immediately became aware of the diversity of the existing designs and the differing setbacks to the film plane of the various film and plate holders of these early cameras. These designs seemed to consolidate to somewhat of a standard in later years but when measuring them I observed noticeable differences from the face of the film holder to the film plane that in some cases would most likely be covered by the lens depth of field but in others the difference such a divergence from the norm that I began to wonder if it was intentional. After studying the setback of the ground glass on various cameras I found it to be true that manufacturers of the time did produce film holders and camera backs that were compatible only with there own equipment and were not the least interchangeable as far as focus but to the casual observer the mechanical fit was perfect. I can't help but wonder how many countless hours were spent by early technicians in there darkrooms trying in vain to figure out where thy went wrong!
The design feature that seemed to exist on all these backs was the rather heavy spring pressures that resulted as the film or plate holder was inserted after focusing was achieved and the difficulty encountered when removing the film holder after the shot was taken. To say it is a two handed operation is perhaps putting it to mildly in my opinion!
Keeping these observations in mind I decided to design a back that could interchangeably accommodate various film or plate holders and incorporate matching ground glass setbacks for whatever brand or type the user would be inclined to experiment with. The solution I developed to work around these problems was to create a focusing glass that is removed before the film holder is inserted. If the side rails that support the ground glass are fabricated to match the film or plate holder focal plane setback and are machined to the same thickness as the sides of the film holder that is utilized, an exact focal distance match can be obtained and the film holder can be inserted and removed quite easily without disturbing the position of the camera.
For the frame of the camera I decided to utilize all friction stop adjustment to remove the stumbling block, for the average experimenter, of successfully fabricating a geared drive actuating mechanism while still incorporating all movements required for focusing or offsets. The method of fabrication I devised utilizes commonly available aluminum channel and standard dimension hardwood that can be purchased from the local home supply store and needs only to be cut to the proper length before construction can begin.
I believe that my design will allow the casual experimenter to enter the world of large format photography at a time when its utilization is becoming completely overshadowed by high priced products a rapid drift toward digital media as the only low cost option with pleasing results. The availability of low cost salvageable components such as lenses, film holders and complete darkroom systems has never been higher and not allowing these fine items to go waste when they can be easily obtained and utilized in the extension of an extremely valuable and satisfying art form is my reasoning for developing this low cost, simple, yet precise method of camera chassis construction.
http://home.earthlink.net/~eahoo/camera.html
Edward A. Hoover
5345 East Ohio Ave.
Sanford FL 32771
(407) 321.5128