The inestimable Mike Taylor found this fascinating article, buried deep in his files, which came from a 1950s trade journal, Motion Picture Projectionist, February 1954.  It could quite accurately be described as the definitive guide for projectionists in setting up for a dual projector 3D presentation.  The author, Gary De Wan, was the Chief Projectionist at the Warner Theatre, London, where he had worked from 1938 until his retirement in 1966.

3D by G.J.J. De Wan

Now it is my personal opinion that, whether we like it or not, 3D is here with us now (and for at least some indeterminate period in the future).  Resulting from this ‘fait accompli’ by the Hollywood film producers it behoves us, in our own interests, to learn and digest all that we can about this new film technique, which has, as it were, descended upon us like ‘bolt from the blue’.

Firstly, let us take the case of what I term as ordinary 3D in its simplest form of presentation.  The minimum requirements here are two projectors, which can be mechanically or electrically interlocked in such a manner that when both projectors are set in motion, neither one of them can (barring accidents) possibly get out of step, or sync, with the other.  Having got this far we must now install four 24” film magazines on the projectors (two top and two bottom).  These in turn house 23” spools which, when fully loaded, are capable of taking 5,000 feet of film.  The reason for such large spools is obvious when it is estimated that the average length of feature films is usually somewhere in the vicinity of between 8,000 to 10,000 feet long.  Therefore, any exhibitor with those requirements is enabled to show (with one interval) any 3D film within those limits.  Next, we must procure a pair of polarised filters, which must be suspended at the same angle as the projection rake in front of the projectors.  Those filters, which must be handled with great care, are usually marked with red and green identification tabs placed upon the corners of them.  Looking at them from the operating position, the filter showing the red tab is placed in front of the number one, or left projector.  The other filter, marked in green, is placed in front of the number two, or right projector.  The correct positioning of these filters is of PARAMOUNT IMPORTANCE, because the viewers that are issued to the patrons are polarised in exactly the same manner.  Any deviation from this inflexible rule ruins the 3D effect and causes severe eyestrain and chaos [Mr. De-Wan really uses the word ‘chaos’ here – Ed.] amongst the patrons.

Where possible, suspend the polarised filters as far away from the projection lenses as practicable.  This will ensure that they will not be damaged by the heat from the concentrated projection beam, which in time will break down the crystal formation of the polarised filters.  If, for structural or mechanical reasons, this is found to be impossible, you will then have to introduce a forced-air draught, which must be constantly directed upon the filters whilst they are in use.  IMPORTANT!  NEVER THROW A NAKED PROJECTION BEAM UPON YOUR FILTERS.

Next, we must have a special screen installed.  Unlike the ordinary type with a matt finish, which unscrambles or de-polarises the projected images, this must be specially treated with a metallic coating, usually made up of an aluminium base.  Not mentioning other numerous technicalities for the moment, we are now basically equipped to show 3D films.  Now as to the method of actually projecting 3D, the following points of procedure MUST, REPEAT MUST, be adopted.

Both images on the screen must be as near as it is mechanically and optically possible to get them in perfect alignment, both vertically and horizontally.  For this purpose, a special lining-up or target film must be obtained.  This can be made up into two handy sized loops, which can be projected continuously and simultaneously on the screen until the proper results are obtained.  It would be as well for this purpose if one machine was first of all centred ‘dead on’, and then the other projector can be lined up in conformity with the master machine.  Having done this, it will now be advisable to securely lock the position of both projectors whilst both images are still being projected upon the screen.  In the interest of good presentation of 3D films, this positioning of both projectors should be carefully checked every morning before the start of the day’s showing.

Lacing up and Syncing.  Both projectors must, firstly, be ‘inched’ until the intermittent movement has just passed into the locked position.  It will now be noted that the flicker-blade of your shutter is about to enter into the vertical plane.  Carry on until this has reached top dead centre.  Having made absolutely certain such is the case in both machines, they must now be interlocked.  Both machines can now be laced up in the usual manner, making sure of the fact that the same start marks of both prints are dead in rack on both projectors.  The projectors are now ready to project a 3D film.

Now here are a few reminders for the projectionists who will be concerned in the showing of 3D films:

1. Make sure that your projectors are properly lined up.
2. Make sure that they are properly synced and interlocked before starting up.
3. Check and make sure that the same start marks of both prints are in rack on both projectors.  A quarter rack or less, even when rectified (after both mechanisms have started), has an irritating and in quite a number of cases, even painful result upon the patrons’ eyes and nerves.
4. Make sure that the light outputs of both projectors are matched as near as possible with the same light density and quality.
5. Make sure that both of your arcs have a sufficient trim of carbons in them to enable you to carry on for the length of the reels concerned.
6. Keep both projector mechanisms in good condition.  Any undue or extraneous picture movement, laterally or vertically, on the part of one or both projectors, will register a deleterious effect upon the extremely sensitive optical nerves of your patrons.
7. Get your focus on both machines correct in the opening stages of the credit titles.
8. Whatever else you do, always use the old and well-tried formula of check, check and counter check.  I cannot stress this point sufficiently strongly in the case of successful presentation of 3D films.  There is no margin or tolerance allowed in this kind of technique.  Either you are ‘DEAD IN OR DEAD OUT.’  In the latter case, you have no option but to shut down and start all over again.  This time, for the sake of your sanity and especially that of your paying patrons, let’s sincerely hope that both projectors and both prints are correctly phased and synced.

At the Warner Theatre, in addition to 3D, we have Warnerphonic stereophonic sound installed.  This has the result of further enhancing audience participation.  This requires an additional film, which carries three separate soundtracks magnetically recorded.  The magnetic reproducer has, of course, to be laced up and synchronised with the other two projectors.  This process, as you may well gather by now, entails the constant handling of quite a large amount of film.  For the statistically minded, here are a few interesting details:  Assuming that House of Wax is allowed to run at the Warner Theatre for 20 weeks, we can then arrive at the following data.  During this period of time, 19,200,000 feet, or 3,636 miles of film will have been shown – and remember that every foot of it has to be carefully rewound and examined.  Taking into consideration the operation involved in lifting this amount of film on and off projectors and on and off rewind benches, this represents a total lifting power of over 280 tons of film.  In so far as I am aware, this must surely constitute a world cinema or theatre record in this period.

There is a pretty severe strain involved, mentally and physically, in the continuous showing of 3D films.  In comparison with normal 2D showing, every operation is at least doubled. For this reason I would strongly advocate that, where possible, no projectionist should be called upon to more than 6 hours of screening 3D films per day.

In conclusion, I would like to remind projectionists that it is largely dependent upon them whether 3D is going to be the success it deserves or not.  There are, in my estimation, wonderful possibilities (carefully and properly exploited) in this new medium of entertainment.  I personally am all for it, and I firmly believe that if it is to be the means, or partly the means, of winning back those lost customers, we should give it our whole-hearted support.

In view of the fact that other equally if not more important revolutionary methods of film presentation are already on the way, we projectionists of today must be fully prepared to play our part.  Strengthened by the inescapable facts that each new technique will call for added responsibility and infinitely higher standards of technical knowledge, precision and skill, it behoves us as projectionists to be on the alert for all future developments, and see to it that this time we make it our business to ‘catch the bus’.

In conformity with the other new forms of film technique which are already looming largely on our horizon, and resulting from the inevitable demands for the attainment and operation of the higher technical standards attendant upon them, it is a foregone conclusion that in the very near future the professional and financial standing of the projectionists’ status will once more enter into the critical sphere, or a crucial crossroads.

Over two decades ago, a somewhat similar technical upheaval took place [sound], which, by reason of its revolutionary nature, presented the projectionists of that time with the necessary potential means whereby the perennial industrial problem of wages and working conditions could have been considerably resolved.  Unfortunately (in spite of the efforts of a gallant few), through lack of co-operation and organisation, the unique opportunity of that generation was apathetically discarded and ignominiously relegated to premature obscurity and eventual oblivion.

Today, we projectionists, with the solid ranks of N.A.T.K.E., are better organised and therefore better prepared to seize this generation’s golden opportunity and use it to its fullest justifiable extent in our constant endeavour to get within measurable distance of that ultimate goal of equitable wages, improved conditions and reasonable security for ALL WITHIN OUR TIME.