International photographer (Jan-Dec 1934)

February, 1934 The INTERNATIONAL PHOTOGRAPHER Five Speed Xenon f:2 lens. It serves as well both for the beginner and the advanced amateur. Drying the Film: It seems tragic that after being correctly handled throughout its processing, the film should receive mars in the last step — drying. This occurs to many miniature camera workers. Drying of the film should not be regarded as just another perfunctory step in its processing. It deserves as much consideration as the choice of the developer. After the film has been washed and hung up to dry it must be carefully wiped to remove all excess moisture. Droplets of water left on the film are apt to cause water marks. The Brooks Film Dryer The selection of the material to be used to remove this excess moisture must be given careful consideration. Ordinary cloth will not serve the purpose, for it contains hard surfaces which are prone to scratch the film. When it has just been removed from the wash water, and especially if it has not been subjected to a hardening bath, the emulsion will be relatively soft and subject to scratches. Suitable materials include, chamois skin, absorbent cotton, a Viscose sponge, and a Brooks film dryer. Chamois cannot be used unless it has first been soaked in water for a sufficient time to render it slimy to the touch. The absorbed water is then pressed from it and it is ready for use. Absorbent cotton is first immersed in water for a few seconds, after which it is pressed to remove as much water as possible, and then used. The Viscose sponge is a new importation by Willoughbys which is very soft, and possesses a remarkable affinity for water. The Brooks film dryer is a departure from the type of wiping agent thus far described. It consists of two rubber rollers between which the film is placed and pulled through. All excess moisture is removed, without the film receiving any scratches. It may be interesting to our readers to know that this film dryer is now manufactured by Burleigh Brooks the well known importer of photographic goods. When using one of the wiping materials described the film should be stroked very gently, and no pressure applied. The material may contain a small piece of gritty matter which will scratch the gelatin, if pressed into the latter. Many photographers keep chamois skin or absorbent cotton constantly soaking in a jar of water, to insure extreme softness before the material is used. This is a wise step. Miniature camera workers who employ absorbent cotton should examine the film closely after it has been dried for small strands of cotton which may have adhered to it. These are easily removed with a soft camel's hair brush. They show up annoyingly when the film is being enlarged. After the excess moisture has been removed the film is hung up to dry. A dust free room is the most desirable. Miniature films should be dried quickly for prolonged drying favors the production of coarse grain. If an electric fan is available it should be utilized. Another precaution necessary is that the film must not be subjected to changes in temperature while drying. Once it has started to dry in a room of a definite temperature it should no' be removed to another room of a higher temperature, so as to facilitate faster drying. When the film has started to dry at its edges and it is then subjected to a higher temperature, a shore line will form along the edge between the dry and wet portions of the film. After it has dried thoroughly the film is cleaned with alcohol or carbon tetrachloride, using either absorbent cotton, or a chamois which has been soaked in the cleaning fluid. It is now ready for printing. Carbon tetrachloride is an ideal cleaning agent for it is an excellent grease solvent. This chemical can be obtained from your photographic dealer, or at any drug store under such trade names as Fabriclean, or Carbona. New additions to the Leica lenses: Two relatively new lenses are now supplied for the Leica camera, the Summar f :2 of 50mm. focus and the Hektor f:4.5 of 135mm. focal length. The Summar serves as an ideal speed lens. Its focal length of 50mm. allows it to serve as a universal objective for the Leica, and its speed of f :2 opens up many new fields to the photographer. The correction is perfect. An image of wire sharp crispness is obtained to the very corners of the negative even when the lens is used at full aperture. It may seem odd that the Hektor 135mm. lens has been added to battery of lenses available for the Leica since an Elmar 135mm. lens has been supplied. The Elmar serves for all general uses. The new Hektor objective is however ideally suited to cases where correct technical detail must be preserved. It also possesses a more superior chromatic correction than the Elmar, and is therefore more suited to color work and infra red photography. Leica users can also avail themselves of Hektor f :2.5 50mm. lens in a collapsible mount which serves as a universal objective, as well as a speed lens. The Summar however possesses superior characteristics. Owners of the Leica camera as well as other miniature cameras can ob Showing Various Objectives of Leica Cameras tain a new interesting booklet on lenses by writing to the E. Leitz Inc., 60 East 10th St., New York, N. Y. This booklet is supplied free of charge and contains many interesting lens facts presented in a novel manner. Notes on fine grain developers: New fine-grain developing formulas are constantly appearing. From time to time such formulas will be published in this column. It would not be amiss for the miniature camera worker to experiment with the various formulas given in this depart(Turn to Page 21) Please mention The International Photographer when corresponding with advertisers.