17.5 MM

 In the process of recovering from the Great Software Diaster of 2015, I am trying to reorganise the 17.5 pages once again, especiaaly by eliminating the two Big Brother chapters. I've done some other pages, eg the Rex, but there is still alot of work to do.

Click Here for Big Brother 1

In one of my attacks of guilt about not contributing to the hobby, I wrote up my 17.5 experiences. The article appeared in ACE Magazine, butI wanted better photo's. Grahame Newnham later put it on his website. It then turned into a continuing story in:-

Click Here for Big Brother 2

I have decided to re-cast what were Big Brother 3&4 and split things up by projector, leaving Big Brother 1&2 as a general introduction. This will, I think, make things clearer for the future as I add material. So:-

Click Here for Pathé Rural - how the small cinema network in France operated and a translated article on its history.

Click Here for Rex (the UK name for the original French Rural)

Click Here for Home Talkie and Natan 175

Click Here for Rural Sonore

Click Here for Super Rural

Click Here for Publicity - I couldn't resist the image of Seymour Hicks, then I found some others worth reproducing.

Further down this page you will see some frame enlargements from both silent and sound 17.5 films, and the story of my efforts to make 17.5 leader.


Nov 2012

My friend Mikael down the road has acquired some 17.5 fillums. He is capable of lifting where I am not, so we dug out the late John Collinson's conversion of a Gebescope Model A which hav huge feed and hold-back sprockets and an intermittent sprocket. This reduces the risk of showing films for the first time that would come with using a Home Talkie. Here are some pix.

17-5 17-5 17-5 17-5 17-5

Those of you who know the Gebescope Model A will note that the conversion is nearer a rebuild. Note that the sound is read on a thing that is not a flywheel, which I have marked. The back is a maze of electronic stuff, but it all seems to work. We are not yet clear how much wow is printed into the films and how much is due to the projector - the pair of rollers below and to the left of the flywheel rotate in a circular direction against a spring. I think the spring may be too strong as the rollers don't move as you would expect. We also found that the machine ran very hot - unsurprising as there seems to be no fan of any sort. As an experiment, I have fitted a 120mm mains extract fan, left over from playing about with cooling a Home Talkie. We shall see if this helps. Finally, note the take-up has its own motor.


Terry Vacani has sent an interesting link to a video of a man threading a clearly damaged piece of 17.5 into a projector I cannot identify. ?cina 17.5mm Emotions?? - YouTube



This is about the only time Pathcope in the UK ever referred to 17.5 silent films........ It's from the Pathescope Monthly for August/September 1932.


Some ads and extracts from Pathescope Monthly dredged up by David Richardson.

17-5 17-5 17-5 17-5


A comparison of the standard 9.5mm Motocamera with the Rural 17.5mm Motocamera. It seem that precisely the same mech was used, all the extra thickness going to the opposite side.

17-5 17-5 17-5


I think these two sketches relate to one of the Home Talkies I have and how it was modified.

17-5 17-5


Below are some frames from 17.5 silent films, sent to me some time ago by Rene Villareal. These illustrate just how superior 17.5 was to the (already-established) 16mm, with a larger image size, aided by those rounded corners that are so characteristic of the gauge. And how much more obvious to start from 35mm and halve it, despite the risk of the unscrupulous splitting nitrate rather than safety stock. Whatever gloss was put on it, the success of 16mm was due to it being introduced years before 17.5 (1923 plays 1926, maybe even 1927) and of course the industrial and commercial might of the Americans and the Germans who came out on their side.

The first set is labelled Chinoiseries, the second Marriage. If anyone can offer info and suggest an order for the pix........

17-5 17-5 17-5 17-5 17-5


17-5 17-5 17-5 17-5

17-5 17-5 17-5


I'm not as good at frames as Rene, but these show some points of interest.

17-5 17-5 17-5

17-5 17-5

17-5 17-5 17-5

The first row is one of the very few silents that seem to have been released in the UK, with what seems to have been standard dual-language titles - other UK releases I have seen are the same.

The two sets of frames from Uncle Tom's Cabin (Le Casbah de l'Oncle Tom in French) show how much of the total area was lost to sound, and I am not sure why. Pathclaimed 17.5 delivered a track the same width as 35mm but, as the Avenger frames show, this could have occupied a bit less space than seems to have been allocated (see the additional margin outside the variable density track which already has its own margin). And finally, we have The Curse of 17.5, the enlarged sprocket hole, here shown enlarged. You can see by the shadow sprocket hole that has printed thru on the left of the sprocket hole the sort of size they should actually be. I have entire reels of film with these, and I have found no way of dealing with that.

You'd better settle down and make yourselves comfortable as this one is going to take some time. The observant may recall that I have admitted to a flirtation with 17.5 when I was a mere nerdling and too young to know better. I had not the skills, or experience, or money, or knowledge, to make anything of 17.5 which, even in those far-off days, suffered all the disadvantages of projectors that were dangerous in the hands of the unskilled or unwary, and which damaged films. I gave it up shortly after I married, passing all of it I had to John Burgoyne-Johnson.

Many years later, when I was old enough and wise enough to know better, and had the time, resources and (nearly) enough money to indulge myself, I once more plunged foolishly into the murky depths of 17.5. As with 9.5, tho' maybe even more so, many 17.5 films (at least those that escaped the dreaded sprocket hole enlargement) had lost their leaders. I have described to you elsewhere (BB1 and BB2) the shifts and contrivances I have been put to to create a workable solution, including dyeing defunct film. However, I have in recent years acquired a number of silent films, and my contrivances failed, basically because the twin-perf sprockets and claw of the Rural/Rex do not accept sound film.

When I first started back into 17.5, I contacted a number of other collectors, partly to see if I could buy films but also for info, much of which I have passed to Grahame Newnham for his list of known copies of 17.5 films. In particular, I corresponded with and met John Cunningham, a very keen 17.5-er and a highly-skilled engineer. He had converted at least two GBL 516 machines to 17.5, plus a Gebescope Model A, a machine with an intermittent sprocket. This offered the hope of projecting 17.5 films that would not pass thru a conventional claw machine. Alongside this, I was making progress in repair techniques, using a tape splicer I designed and had made and later a couple of 16mm CIR conversions. I see CIR now offer one that costs nearly as much as mine did.

Several years later, John sadly passed away, and his 17.5 films and projectors were dispersed among his circle of fellow enthusiasts. Then after another couple of years, I got out of the blue an offer from one such enthusiast who was no longer able to cope with 17.5, for me to purchase everything he had.

He told me that John Cunningham had asked him specifically to offer the stuff to me when he felt it time to let it go. I was flattered and delighted,

and became the proud owner of many 17.5 films but, even more important, of one of the converted GBL 516 projectors AND the converted Gebescope Model A, which I had come to view as the Holy Grail of 17.5 projection.

What was also among the collection I purchased was a perforator, designed and built by John. I believe it may have been used to create some Duplex camera stock which Grahame Newnham used to film. I believe also that John and his friends also had in mind to re-perforate 17.5 films that had all their perfs damaged, and the machine as I got it was set up to cope with film 17.25mm wide, to reflect the shrinkage of film over time. I particularly wanted to use it to make opaque leader, from unperforated 35mm stock, of which I acquired a small amount from Tony Scott, for both sound and silent films. This sort of thing is well beyond my engineering capabilities, so I had a new punch made by an engineer, which could be used for either single or double perforations. He also adjusted the machine to accept 17.5 film, rather than 17.25. I believe the machine is capable of adjustment to suit all sorts of gauges, but this goes into mathematical regions far beyond my ken. It is extremely clever; as well as the punch synchronising with the little claw that pulls the film thru (using the newly punched perfs) there is a registration pin which descends to fit in a perf just before the punch itself descends, thus holding the film steady. It will be obvious from the pix following that this is an engineer's machine - parts have been adjusted, re-modelled and re-used with no regard for the appearance of the final result; function is all.

The original motor was from an Ace (see separate pix), giving a nice steady throughput, but with the changes it seemed to lack the strength. I experimented therefore with the motor shown fitted, a 110v jobbie from a defunct Ensign machine. I tried using a standard household lighting dimmer control for the speed, but the adjustment doesn't work well - seem to be flat out or stuck. Anyone know of a circuit for controlling such motors?

17-5     17-5     17-5     17-5     17-5     17-5     17-5

So far, so good but, given my approach to cine (which the uncharitable would describe as dilettante at best), any particular topic tends to receive only intermittent attention and it has taken a long time to get back to this. The first thing I found out was you do have to have accurately slit film. The only slitter I have ever come across before is the triple 9.5 from 35mm one, when it was being used by Novascope; a ferocious and terrifying beast, all rotating cutters, running at immense speed. Some years ago I tried making one out of Meccano(TM) and rotary cutter blades, but I was way too ambitious, wanting it to do 28mm as well. It took all my strength just to pull film thru this over-complicated labyrinth, and accurate it was not. Then one came with the perforator; essentially just a channel with a pencil sharpener blade for the cutting. Trouble is, it was set up for 17.25mm. I subsequently purchased one, I think via eBay or maybe direct, it was just a small block with a razor blade inset, and a top to hold the film down (the earlier one had a wooden block to insert in the channel for the same job). The trouble with both of these was it seemed almost impossible to pull straight enuff to get a constant width. The channel one in particular delivered the film nice and straight, but the blade was right at the end of the channel and as I pulled, the film inevitably angled and threw the width off. This caused the perforator to jam. So I ended up with the set-up in the thin pix below, which actually seems to work. It just combines the two slitters to provide a follow-through which, like in sport (of which I happily know little), seems to be an essential part of performance.

17-5     17-5     17-5

My problem now is that I can't get the perforator to run correctly for more than a few feet at a time. What happens is that the punch seems to go very slightly out of alignment with the die plate and fails to punch out the perfs correctly, so the film stops and then the claw rips it. This problem I have yet to solve. I will tell you all about it one day.

This site was last updated 05/01/14