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The Pathé 28mm Film Gauge

In the Beginning

Right from the invention of moving pictures around 1895, amateurs as well as commercial concerns had experimented with cinematography. However there were a number of major snags for amateurs attempting to use the 35mm film size - the cost; the sheer size and weight of the equipment and the fact that the film stock (nitrate) was highly inflammable! A few systems aimed at amateur use came and went, but around 1910 there was a major development - Pathé in France and Eastman Kodak in the USA introduced a non-inflammable acetate film base. In the USA Edison used this new film stock to launch a 22mm amateur film size, with three 6mm x 4mm pictures across the film - but not being really mechanically practical, it died without trace. However in France the giant Pathé concern (probably at the time the largest film entertainment company in the world) launched another new film size - 28mm. With 28mm, Pathé-Frères turned their attention to cinema in the upper class domestic environment. Around 1910 Arthur Roussel was commissioned to develop the equipment. On a non-flam. base, the 28mm wide film had 1 sprocket hole per frame on one edge of the film, 3 on the other; the large image size of 19mm x 14mm (not much smaller than 35mm) enabled a good quality projected picture.

The 28mm Pathé KOK cine projector

As few houses had mains electricity, a big feature of the KOK projector, patented in 1911, was dynamo lighting. Illumination was provided by a 6 volt 0.75 amp lamp contained in a lamphouse similar in design to the later 9.5mm Pathé Baby. The dynamo was belt driven from a large flywheel connected to the main shaft. Turning the handle at a steady pace gave a well illuminated 30 inch picture. In the UK the machine sold for £15 including two printed films, screen, metal carry case & cleaning outfit. A battery was available for an extra 35/- so still frames could be projected.

Construction was based on a cast alloy central frame to which the mechanism was fixed and this frame was mounted on a large wooden baseboard over which the metal cover was clipped. Extensive use was made of castings in the KOK and the aluminium alloy used gave stability without excessive weight, to allow portability. Spool capacity was about 400 feet (around 7 inch diameter) giving up to 8 minutes running time at 16 frames per second. A single sprocket was used to feed the film to and from the wide opening gate. Intermittent motion was provided by a claw which rode back gently on the surface of the film on its return stroke. A single shutter blade rotated in front of the gate, enclosed in a front casing. Flicker was visible though not unpleasant, because of the low level illumination.

A later version of the KOK used a dropper resistance, so that the lamp could be operated from AC or DC mains electricity. These mains versions could also be supplied with a motor (fitted in the dynamo position). The lamphouse on the mains version was larger with a cooling vent on top.

28mm Printed Films

In addition to safety, another advantage of 28mm film was that it contained 20.5 frames per foot, compared to 16 frames on 35mm film. A 400ft reel of 28mm is equal to over 500ft of standard 35mm film.

The 28mm printed films were optically reduced from 35mm originals. Unlike the later 9.5mm practice of editing the narrow gauge versions to a convenient length, the 28mm versions were usually issued in their entirety - many films produced from 1905-1914 now only survive in this gauge. The first catalogue offered 48 films from 45 to 90 metres long. By 1920 the catalogue offered 2,000 reels. Films were sold at 2d a foot and a library service was also available with 12 subjects a week offered for a subscription of 10 guineas a year. Full length films were issued, and included films from most of the film producing countries. Douglas Fairbanks and Broncho Billy Anderson appeared on this gauge plus some of the spectacular Italian religious silents. The 28mm films were beautifully clear & the projected picture quality was very good indeed.

The 28mm Pathé KOK Cine Camera

In the same year (1912) came the KOK 28mm camera; quoting from the manual:- "No elaborate directions are needed. There is even an automatic indicator showing just the right speed at which to turn the crank. It is equipped with a fixed focus Zeiss anastigmat lens of 1.75 inch equivalent (45mm focal length), with a speed of f4.5. It has lens cap, sunshade, iris diaphragm, spirit level, view finder, film length indicator, perforator for marking end of each subject, and contains two film magazines with the unusual capacity of 400ft of 28mm film. Spools of 100, 200 and 300ft length are supplied. Size 12 inches long, 6 inches wide, 10 inches high, weight 12 pounds". The advertised price of £21 included a sturdy tripod, an essential accessory for this rather heavy, bulky hand-turned cine camera. At the time, the reversal process had not been introduced, so negative (advertised as non-inflammable) 28mm film stock was offered at 2d per foot - a 120 metre (394 foot) spool was 66/- (£3.30). The exposed spool of film was returned to Pathéscope for processing and production of a positive projection print - again at a cost of 2d per foot.

The KOK 28mm cine camera was similar to the Pathé 35mm camera, designed to be hand-cranked on a tripod, like most movie cameras of that period. On the side was a visual indicator which showed when the correct turning speed was achieved. The camera body was made of leather covered wood with a hinged front panel for access to the lens and a rear cover which opened upwards for full access to the entire film compartment. The supply and take-up spools were in enclosed metal drums to permit daylight loading. The main mechanism was mounted on a cast aluminium-alloy centre plate which divided the film compartment from the front mechanism section. Velvet covered pads held the film in engagement with the chain-driven sprockets, which unlike the projector, were symmetrical with three teeth per frame on each edge. The 28mm negative film had perforations at 5mm pitch on each edge, whilst as already mentioned, the print stock had three perforations on one side and one on the other per frame. (Incorrect threading didn't apply with the camera). It is thought that the 28mm negative camera film was in fact nitrate stock, but only the positive print on safety acetate stock was returned to the user.

The side-by-side film loading arrangement required a partly twisted lower loop and a velvet covered guide started the film in this loop as it left the gate. Intermittent motion was provided by a claw pull-down with a single claw on either side of the film. A double cam oscillated the claw frame on its vertical guides, extending the claws on pull-down stroke and withdrawing them on the return stroke.

In the front section of the camera the driving shaft was geared to the claw and shutter mechanism and to the chain drive for the sprockets. A supplementary gear train operated both the footage counter and the centrifugal actuator of the speed indicator. A punch for marking the film was operated by a knob on the side of the front section. On top of the camera the viewfinder comprised a front diverging element with cross-lines and a rear peep sight. Near the front finder lens was a red bubble level. The camera lens, a 45mm f4.5 anastigmat in a helical mount, carried no focussing scale. Set at its hyperfocal distance for normal use, it could be critically focussed if a screen was applied to the film gate from the film compartment.

Pathé Frères (France), Pathéscope (UK & USA) and the 28mm Filmsize

The Pathéscope company was formed in the UK in December 1912 as the agents for the Pathé Frères 28mm KOK projector and the hand turned 28mm camera. Effectively the UK company was what we would now call a franchise - being set up with UK money, but with 10% of the issued share capital value being immediately paid in cash to the French Pathé Frères company who also retained 100,000 one shilling special 'participation' shares - the other 100,000 ordinary £1 shares being purchased by the UK shareholders. This meant that the French parent company also received half of the future profits. In turn, the UK Pathéscope company made Houghton's Limited of High Holborn, their main UK distributors. Exports soon began to other overseas countries like the USA.

The 28mm KOK system proved a commercial success - not only in the home, but in schools, churches and clubs. It was claimed that by 1918 over 10,000 machines had been sold and over 25,000,000 feet of positive film had been produced. However with the worsening of World War 1, production of 28mm equipment in France ceased. In the USA and Canada other 28mm projectors appeared together with new 28mm film releases. When supplies of the French made KOK (sold as "The Pathescope" in the USA) ran out, the American Pathéscope franchise designed a newer model - the Pathéscope Premier. Soon another company launched the Victor 28mm projector. But with the introduction of small, lightweight, true amateur equipment in both 9.5mm and 16mm sizes, the writing was on the wall for 28mm. Already phased out in Europe, it struggled on up to the late 1920s in the USA and into the early 1930s in Canada. Today it's a forgotten film gauge, but highly sought after by specialist collectors around the world. Both films and equipment, now almost 100 years old seem to have survived rather well - sadly today's electronic devices are lucky to survive for even five years and rapidly changing formats mean that even now, many early electronic formats are unplayable - so much for progress!

Further reading - The History of Movie Photography by Brian Coe - ISBN 0-89860-067-7
Further 28mm info at www.cinerdistan.co.uk .......(Martyn Stevens)
Further 28mm info at www.pathefilm.uk ...............(me - Grahame Newnham)


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Created Febt2010 .. Last updated 01 December 2014 ......... 28notes.htm ......... © MMX Grahame L. Newnham