Amateur Photographer & Cinematographer (1933)

The AMATEUR PHOTOGRAPHER n 6 CINEMATOGRAPHER a October 25th, 1933 mateur NEWS, NOTES AND MATTERS OF IN¬ TEREST FOR ALL CINEMATOGRAPHERS USING AMATEUR CINfi APPARATUS. Cinematography Projector Efficiency S. E. L. MOIR. The cinematograph projector can stand up to a lot of rough usage, but sooner or later this has to be paid for. It is far better, however, to maintain the instrument at a high standard of efficiency and to remedy any defects before they can seriously interfere with displays. NO projector — not even the finest “ super ” ever heralded upon the market — will automatically give of its best for all time. After a while, the results of continual usage are certain to manifest themselves in the form of less brilliant pictures, heaviness and straining in the pro¬ jector mechanism, loss of film loops — sometimes accompanied by " chopping up ” of the film itself — and even more serious troubles. Most of the defects involved are quite recognisable and do not easily escape notice ; but the others are more insidious : they very gradually creep on, and may escape detection for a considerable period. Loss of brilliance in the screen picture — one of the “ slowly-progressive ” defects which affect the projector — is often tolerated for months without sus¬ picion, and this is only one of the defects referred to. Oiling. Usually, most of the mechanical troubles affecting projectors can be avoided by the periodical application of a suitable lubricant. The light mineral oil sold at Messrs. Singer’s sewing-machine shops is ideal for use with nearly all projectors. For the benefit of those in any doubt as to where to apply the oil, it may be remarked that generally the oiling ducts are marked by letters or indicated by a colour device — and generally an oiling chart can be obtained from the makers. Certainly, both sprockets require frequent oiling, and so does the shutter spindle. Other parts, including the intermittent action, also require oc¬ casional lubrication, but as they usually run in grease the need for this tractable addition is less frequent. Sometimes associated with the pro¬ jector (though not, of course, an integral part of it) is the motor. This, too, requires very frequent lubrication, but only at the bearings. No oil whatever should be allowed to come nto contact with the wound armature, or especially with the commutator. The latter, together with its twin carbon “ brushes,” should be carefully wiped with a dry cloth immediately after each application of oil to the bearings. Readers should particularly note that the value of any application of oil is almost entirely lost if stale and gritty deposits are not first cleared away. Time permitting, each bearing and duct should receive a preliminary cleansing with kerosene ; accessible parts should then be properly dried, and only when this has been done should the fresh lubricant be applied. Mechanical Play. Quite apart from the necessity for oiling, absence of sufficient “ play ” in the moving portions of the mech¬ anism is 'apt to lead to stiffness and thus to lower operating efficiency. In this connection, let us consider the motor itself. This can supply adequate power only when there is an almost complete absence of friction between the armature shaft and its bearings. Now these bearings are usually adjusted by means of the retaining screws, so that it is not a difficult matter to increase friction, i.e., to reduce the amount of power available for transmission. And not only will this reduce the speed of projection, but, in extreme cases, it may lead to overloading and a possible burning-out of motor windings. Then, of course, there should be ample play between the shutter and its protective casing. Any fouling of the sides may lead not only to un¬ wanted noise and friction, but also to some risk of damaging the blades of the shutter itself. For a similar reason, there should Fox Hunting starts on November 1st. A variety of fine action pictures for the amateur cini worker will then become available in all parts of the country. A pictorial setting is advisable for these subjects. 30 389