Topic – A Falling Plate Camera

Some background

In the early days of camera the technology of the day ordered glass plates for carrying the film emulsion. Usually the camera was of the bellows type, and usually they required the use of an individual film plate holder or cassette for the glass plate. That is exactly how todays large format cameras work, well, except for the glass plate, we now use sheet film with the emulsion on polyester base.

The lenses were simple by todays standards and were corrected only for the most rudimentary optical aberrations. The simplest ones were made of two lenses cemented together into one unit. Due to the manufacturing process and glass quality the focal lengths were quite long, which is probably good as wide angle lenses require more optical design and consideration in the first place. Despite these shortcomings photographers took photos with these.

The traditional glass plate holder contains one glass plate on each side of the holder and covering dark slide on each side. One holder so holds two negatives. It was, and is, fiddly at best and cumbersome to use. So as a response to the glass plate holder inconvenience some cameras were loaded with a magazine of glass sheets with a significantly simple holder. Then a lever on the outside of the camera allowed changing to a new plate.

The camera

A few days ago I was given one of these old so called falling plate cameras. It is of swedish origin and manufactured by Hugo Svensson & Co, Kamerafabrik, Göteborg. The type of camera is “Svensk Express 4B”. This individiual is #260 as is stamped inside of it in at least three places. There is not much on the net about these old boxes but I have found that the falling plate camera business started back in 1893 and continued a decade or so into the 20th century. Given the scarceness of information of course this one has to be studied more in detail. Mind you this comes from some hundred years back!

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The box measures 209x104x162 mm (roughly 8x4x6 in). On its front are its controls: distance, shutter speed, aperture, mode (normal, T or B in todays parlance) and shutter release itself. In the upper left of the picture is the “next plate please”-lever.

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The back opens after releasing two latches and reveals the plate changing mechanism as well as the film plate counter in the lower part of the back door. The spring in the door serves the double purpose of keeping the plates in place as well as pushing the entire stack forward when so required by manoeuvering the lever on the outer upper right side.

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The glass plate holders are simply metal sheets bent so as to hold the glass in place. There are six of them in this camera and they accept 9×12 cm plates.

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This picture illustrates the plate holders in place. The vertical ones are yet to be exposed while the two lying on the bottom of the camera are already used. Of course normally the plates would be kept in complete darkness and the entire loading-unloading routine would have to be carried out in a darkroom.

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This is a sketch of how a falling plate is dislocated and falls down, out of the way for the next plate in the magazine. In the upper left there is a little semicircular hook that moves down and stop the next plate from falling while allowing the front one to release and fall. The mechanism works surprisingly well (an euphemism for “so-and-so”:) and with perhaps a slight nudge or two one can clearly hear the metal flapping inside when it falls down. If it does not work, then it has turned into a failing plate camera…

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The humanoid like front has all the controls! From the top are two viewfinders (the “eyes”), a distance setting (the “nose”), the lens and aperture itself (the “mouth”) below which it is getting increasingly hard to find human counterparts. The large knob below the lens is for cocking the shutter and the lever sets the aperture. The aperture has a full selection of f/11, “S”,  f/14, f/22 and f/32. The “S” simply sets a blind before the lens, unknown why. The shutter release is the round knob to the left, it goes inwards. At the bottom are two controls: the “T”, “B” or normal (“Ö”, “T” and “M” just to confuse) and in the center one can select shutter time (1s, 1/3s, 1/10s, 1/25, 1/50, 1/100, 1/150 or 1/200). Note you can select a shutter time, it does not obey the setting – nor did it ever methinks. The mechanism is so crude I could have invented it myself! There is a small shutter adjuster screw below the selector which does just that “adjusts” the shutter. God only knows into what though!

A peek inside of the shutter and lens

Removing four wooden screws releases the front. This is not the ordinary use of the camera but for servicing, better left to the camera technician (or motor mechanic in town more likely…)

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Anyway the front comes off easily (which reminds me of this gem http://youtu.be/3m5qxZm_JqM).

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The entire lens/shutter assembly. The number “260” is seen to the right and one cannot miss the huge lens in the middle. The lens is 37 mm in diameter  and is held in place via a screw that presses the upper slit together. The brass screw on the right of the lens connects to the distance setting rod. Lets remove the lens to see better how the mechanism works.

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Here the shutter is uncocked. The upper left spring is contracted and in rest. The arm at the bottom controls the “T”, “B” or normal setting. Shown above it is in the normal mode.

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Here the shutter is cocked. It is cocked by rotating the disc CCW until the lower arm’s peg catches the disc’s rest as above. Note that the spring is now pulling the arm from the brass hinge to left. The arm centered on the pinion is clamped between some cork (?) that is supposed to slow down the pulling movement (yeah, dream on!).

With the scene set like this, a push on the shutter release lifts the lower arm to let the peg slip over the disc’s rest. The spring then pulls the arm and the disc’s circular movement completes. If you look closely there is a sector of the disc missing between the disc’s rest and the right long claw, this is what opens the shutter as the front hole and aperture is below the center of the lens (now removed). Anyway, the sector sweeps over the aperture hole and the exposure is done!

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In the “T”-setting above the lower arm is moved more to the center of the disc. When cocked, the peg rests as before, but the shutter release only releases the disc for a 1/8th turn as it rests again on the second, next (slightly higher) rest of the disc. Here the exposure starts.

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Now the shutter opens and is kept open. I had to simulate pressing the shutter by pulling the lower arm in the picture above.

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Releasing the shutter now keeps the shutter open as the peg now rests on the smaller, slightly to the left of the rest used in the above picture. Next press of the shutter release actually lets the spring pull and the disc completes the revolution as before.

If you have followed the description this far it will come as no surprise that a lower arm in a middle position will work exactly as in the “T”-setting above but just slightly miss the last rest, thus working as a “B”-setting.

Aperture and distance setting

Drawn somewhat to scale one can deduce a focal length of 120 mm for this camera.

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It is however odd that the aperture is place in front of the lens. The largest diameter of the disc is a mere 12 mm effectively avoiding using the lens’s full aperture. Strange, but perhaps wise as optical distortions would grow into hilarious proportions full open?

A quick gauging of the apertures gave f/11 – 12 mm, f/14 – 10.5 mm, f/22 – 6.5 mm and f/32 – 3.8 mm. These numbers are not quite consistent with a fixed focal length but close for all practical purposes. I was initially suspicious to these numbers but common apertures seems the most likely after measuring them.

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The distance setting is the smallest control on the camera but apparently is awarded the biggest picture in this review. The scale is in meter and a full stroke is some 10 mm. This pushes the lens to and fro by the same amount. Of course the scale relies on the lens being mounted correctly. It took some turns of trial and error before the lens was seated at the proper location in its rather generous holder.

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With the camera propped up I  shot this view through the living room window. The image is projected on a piece of ground glass I had around. It only needed trimming on the edges to fit.

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The picture does not win any awards (the pot-plant effectively stops that) but proves that the camera has some potential. With a black cloth the image appears much brighter as well as contrastier. The extra stray light from the window into the capturing camera really messes this one up.

Now I cannot wait to put some film in this one!

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5 Responses to Topic – A Falling Plate Camera

  1. stawastawa says:

    so much fun! nice run through!

  2. opobs says:

    Fascinating – I’m just in the process of writing a blog about my own falling plate camera, do you mind if I place a link to this page please? The shutter mechanism on mine is even more primitive than yours.

  3. Pingback: Falling-plate camera | opobs

  4. Thomas says:

    Hi!
    Thanks for a interesting description. I have one myself and would like
    to make it work with film. Did you try it with film and if so what kind you use?
    I havn’t figure it out how to attach the film to the plates.
    /Thomas

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