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THE CELLULOID IMAGE


CONVERTING THE 16MM
EX-GOVERNMENT G.G.S. CAMERA
FOR ORDINARY FILMING
(C.G. Edwards - A.C.W. August 17th 1961)


Two or three twist drills,
a file and a switch: a few
hours' work with these
and a useful (if oddly
shaped) 16mm camera
can be made from the ex-
government G.G.S. Mk3

 

After conversion, the G.G.S. Mk.3 is in some ways a more versatile 16mm. camera than the better-known G.45. It has an f/1.9 lens stopping down to f/16, taking speeds of 16 and 2 frames per second, and a variable shutter giving exposure times of 1/50, 1/100, and 1/300 second, the exposures being the same whether the camera is running at 16 or 2 f.p.s. What these features would cost in a production model on sale directly to the public hardly bears thinking about! Yet the G.G.S. was available at around £3 for used models and £5 for unused, while spare 25ft. magazines cost about 50p each.(in 1961!) These prices include a cable assembly complete with a special, and indispensable, jack. Incidentally, the camera is usually packed in a wooden case which makes a first-class box for slides.

Because of the right-angled optical path in the G.G.S., films made on it have to be projected with the emulsion opposite to the usual position (i.e. facing lamp). However, with double-perforated l6mm. this is of no consequence, provided the shots do not have to be inter-cut with film from other cameras.

Converting is done in four stages: viewfinder hole, wiring, filling in the open front with wood, and fitting a tripod bush.

Viewfinder ~ This is simply a rectangular opening in the main plate immediately below the lens, plus a round spy-hole in the metal cover. Both must be carefully positioned. With the mechanism plate side upwards, and the electrical inputs away from you, mark the centre line of the lens immediately above the lens carrier (Fig. 1). The exact centre can be found quite easily by revolving the orange filter and making a mark where the edge of the half-circle cut-out comes; turn the filter through its full circle and again mark the edge of the cut-out. You will now have two marks 1 /l6inch apart, and between them is the centre line (A) of the lens. Now scnbe vertical lines 3/l6inch to either side of the centre line, and also two horizontal lines (squared off from the edge of the camera) at l/8 inch and 3/8 inch away from the filter recess around the lens. The result is a scribed rectangle 3/8 inch wide x 1/4 inch high (B), which, being the front end of the viewfinder, should be marked out as accurately as possible.

Next, diagonal lines are scribed across the rectangle to give the centre for drilling. Use a 1/4 inch diameter drill for this and be ready to stop drilling when it just breaks through. Remove the camera's outer cover - held by five screws (C) round ihe edge, plus two (D) in the cover on either side of the nameplate - and complete drilling of the hole from the inside of the panel; this is to prevent bits of swarf getting into the works.

Keep the four green wires clear of the hole, and replace the cover by the two screws through its face. Then, putting the drill through from the original side, lower it until - guided by the hole in the mechanism panel - it just meets the angled part of the cover. (Only mark the inside of the cover with the drill, or the angled side will pull the drill over out of line.) Again remove the cover and carefully drill the hole straight down through it, taking care to keep the drill vertical despite the angle of the case. This makes the spy-hole for the finder, and it can be cleaned up with a file if necessary.

Returning to the front hole, file out the 1/4 inch hole first drilled to make the 3/8 x 1/4 inch rectangular opening marked out by the scribed lines (Fig. 2), again taking great care to keep the filings out of the works. The viewfinder is now complete.

Fig.2 Viewfinder rectangle
(arrowed) filed out. Note
that one edge corresponds
with the outer edge of the
cast partition dividing the
camera mechanism from
the power input compartment
(from which one of the two
shrouded jacks has been
removed).

Wiring.- The G.G.S. is electrically operated and needs a direct current supply of 24-28 volts. The cable to the battery normally has three wires - positive feed to motor, positive feed to solenoid, and common negative - but for ordinary filming it is not necessary to feed the motor and solenoid independently.

From the standard cable assembly, remove the metal braiding. The red (motor feed) and green (solenoid feed) wires can now be joined together at the battery end, ready for connection to the positive terminal. The blue wire goes to battery negative. Note that if the battery is already connected there will be a momentary short-circuit across it as the plug is pushed into the camera, so it is better to fit to the battery box either a switch or some sort of connecter which can be plugged in after the camera plug is home.

The female jack socket at the end of the cable fits either of the two four-pole jack plugs in the camera. As the view-finder hole is close to one of them, however, I found it convenient to unwire and remove this jack and use as a power input only the one on the other side (Fig.2).

For starting, the camera can be fitted with a press-button on the mechanism-plate side (Figs. 1 and 4) or, as an alternative, a switch of the press-on/ press-again - for-off type. The press-button is mounted just behind the wires to the plug. Cut the black wire just after the jack terminal, add extra wire to each end and insulate the joins with tape. Then (Fig. 3) drill a 1/8 inch hole in the panel, smooth its edges and thread both the extended black wires through it to the press-button terminals.

Fig.3 Magazine in place,
but magazine cover removed
to show threading. Arrow
points to hole drilled to take
leads to and from push-
button on the front panel.

Filling In - The appearance of the camera is enhanced by closing in the front (lens) side of the mechanism plate with a piece of hardwood 5 3/8 x 5 x 5/8 inch thick, shaped to match the slope of the sides of the body (Fig. 4).

Fig. 4. Front view of converted
camera after space between side
plates has been filled in with the
hardwood panel. Parts lettered
are: X: push-button; Y: keyhole
-shaped cut-out for lens and
viewfinder; Z: tripod bush.

The original mounting clips can be removed. The wood is cut away to fit round the press-button, and a 1 3/8 inch hole is bored (before fitting, of course) to correspond with the lens position. The hole is then extended downwards, like a keyhole, to give ample clearance round the viewfinder rectangle. The wood should not be fitted until completion of the next stage.

Tripod Bush - For this I used a metal plate 3/16 inch thick and about 1 inch in diameter (though it could he rectangular). A 1/4 inch Whitworth hole is drilled and tapped in the plate, and two holes are made, on about 11/16 inch centres, for countersunk wood screws. Before screwing the plate into position (Fig. 4), cut down the wood and the narrow metal ridge on the camera to the level of the side of the body, in order to give a good seating. The overhanging edge of the tripod bush plate can be cut off and filed flush with the edge of the wood and camera.

Finally the wood is blacked all over and polished before being attached to the G.G.S. by means of countersunk screws through the side plates.

Power Supply - Cycle or handlamp batteries can be connected in series to make up the voltage, or a pack of the small Nife cells now available from the ex-Govemment stores can be used. Due to the fairly heavy current consumption of the camera motor and solenoid, there is an appreciable voltage drop in the batteries. For example, with four new 6v. square handlamp batteries (e.g., Ever Ready No.996) in series, the nominal 24v. drops to 20v. on load. It is advisable to use five of these cells to keep the running voltage within the range 24-28v.

Operation -When trying out the camera, note that the claw will not engage the film until the camera's magazine door (which depresses the small plunger at the top of the magazine compartment) has been closed. Then, after a few revolutions of the motor, a change in pitch indicates that the film has begun to move.

The ex-Govemment film that is likely to be used with the G.G.S. comes in 25 foot lengths, wound emulsion out. One roll should he brought out into the light (close the rest up first!) for practice in loading the magazine. This sacrifice is well worth while.

The magazine has an indicator for FULL and EMPTY. If the film is going through properly, the pointer - which can he watched through the transparent window in the door of the magazine compartment - will pulsate. When loading, make sure that the roll of film lies quite flat, and that its ends are not sticking up where they may rub between the sides of the magazine and possibly jam.

When confident that you can load a length of film in total darkness, put in a roll for testing. Once its cover is on, and locked in place by screwing in the captive star screw, the magazine can be brought out into white light; only the frames of film actually in the gate will be fogged.

I find the most comfortable position for holding the camera is against the forehead with the left eye to the viewfinder. This must be at the bottom; you will get reverse action if the camera is used the other way up. The orange filter is not used for normal filming.

The films can he processed to a negative (for printing at home or by a laboratory) or to reversal (though not all ex-Government films suit reversal processing), and must be projected with the emulsion side to lamp (reversal), or emulsion to screen (negative-positive).

The lens is a fixed-focus type. After trying three of these cameras I can report that on them all the lenses were so set that reasonable sharpness extended from about 10 feet to infinity at f/1.9. The depth is much greater - from about 3 feet. to infinity - at f/16. It is simple to set up a scale and make a focus test from various distances.

My films have been processed by Microfilms Ltd. of Dundee (usual disclaimer from a satisfied customer!). The G.G.S. has given results which considering the outlay - and considering that the camera was designed for very different applications - are surprisingly good.


Sadly these cameras seldom appear for sale these days; cheap 16mm ex-government black & white filmstock is no longer advertised and generally we must rely on home processing for black and white work or pay high prices at a professional lab. However Kodak still supply 16mm black & white filmstock - check the internet for suppliers. I wonder how many people did use a converted G.G.S. or G.45 for filming, rather than strip them for the various motors, solenoids and gears etc.? (editor)


 


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First published March 2004 ........ Last updated: 19 October 2012 ........ cel06.htm .......... İMM1X-G.L. Newnham