Amateur Photographer & Cinematographer (1933)

June 14th, 1933 iHi AMATEUR PHOTOGRAPHER ta 6 CIMEMATOGRAPHER a EFECTS in Roll-film With .he a..„os. 1\JP A TTX/P Q universal use of 1 1 V IHO roll film, the following article which deals with defects peculiar to this form of negative material may be helpful to many photographers. The older generation of photo¬ grapher regarded roll film as material for the snapshotter, and productive of results that were invariably inferior to those obtained upon plates. This is no longer the case. It is now realised that for almost every branch of photography the results will not suffer because roll film is the nega¬ tive medium, and with the modern product they may be even better. Camera Troubles. By reason of the fact that the film has to travel over a surface both before and after exposure, we have a possible cause of scratched negatives. Most modern roll-film cameras are fitted with rollers to assist in the smooth passage of the film. Care must be taken to see that these are not bent, and that they run smoothly. Some cameras have a spring plate fitted to the back with the object of keeping the film flat, and the pressure thus exercised must not be too great. When loading the camera it is important that the film should be evenly threaded, and will run smoothly ; this is especially the case with the modern cameras of very compact type. With regard to the latter,, the bellows when the camera is folded are often in contact with the film. Xo harm will result, but the film must not be wound on with the camera closed. Many scratched negatives I'esult from this practice. Scratched Negatives. Perhaps the most common of the defects met with in roll-film negatives is the series of scratches across the negatives resembling telephone wires. Winding the film with the camera closed will cause them, but a common cause is the presence of small sharp particles of grit in the camera. This is especially the case when working at the seaside. Slight roughness upon any part of the camera body where the film may be in con¬ tact will produce the same result. Another and oftqji unsuspected cause of scratches is the practice that some photographers have of twisting the film tighter upon its spool after removing it from the camera. This is quite unnecessary, and is certain to produce abrasion. Any well-designed camera will wind with sufficient tightness, and there is no need to improve matters. Fog. Many excellent negatives are spoiled by fog, either at the edges or ex¬ tending to the whole of the negative. The causes of this defect are many and varied. The most common is that of allowing the film to become partially unrolled, when loading or removing the exposed film from the camera. This operation should be conducted in subdued light, especially when dealing with super sensitive or panchromatic film. A loose-fitting back, or light leak¬ ing in at the winding-key, will cause fog, and if the latter results from this cause it may be recognised. A negative may be fogged, but the edges are clear. This points to fog in the camera, and not to an unsafe dark-room light. It may happen that some negatives are fogged, but not others, or the fog may differ in extent. This may mean that the photographer made several exposures rapidly in succession, and the film was wound into the protecting paper before the trouble had time to affect it. We have known cases where fog resulted only after pro¬ longed exposure in the camera to a thin spot in the bellows. Tracing the Cause. A good way of finding out exactly where the light enters a roll-film camera is to place a piece of bromide paper in the camera large enough to occupy the whole of the back normally taken by the film. The red window may be covered by an odd piece of black paper. The camera should be taken into the strongest light, with the shutter closed, and its position changed frequently, and allowed to remain for some hours. The bromide paper is then developed, fixed and washed. If fog is seen in any particular part of the paper the exact source of the trouble can be traced. Mechanical Defects. In the case of small negatives intended for enlargement these must be avoided. It is realised that a film is not as easy to handle as a glass plate, but it is only a matter of taking a little care. There are two surfaces that may be damaged. Dishes and all utensils must be free from roughness. Dirty dishes and solutions will tend to cause a deposit to form on the negatives, as well as lime salts present in some service water. It is a good plan to give all negatives a bath of 2 per cent acetic acid upon the conclusion of the washing, followed by another rinse before drying the film. When roll films are developed in a tank it frequently happens that the backing paper sticks to the film and causes matt surface patches on the gelatine. These markings may be ignored if contact prints only are being made from the negatives, but they show definitely if enlargements are made. Care in winding the film on the apron of the developing tank and frequent turning and agitation of the tank when full of developer will assist in preventing these markings. If they occur, however, they can be removed by polishing of the back of the negative with the well-known Baskett’s reducer. Lastly let it be pointed out that finished negatives demand care in storage ; the best course is the use of the commercial envelopes sold for the purpose. 549 9