It is quite common nowadays to see expensive lenses without lens caps to protect them. The cap is seldom used for making exposures but it should cover the lens at all times when it is not in use. If lens caps were universally used on lenses, for the protection they afford, there would be fewer complaints traced to dirty lenses and fewer chances of scratching their highly polished surfaces because of the necessary cleaning.

If your negatives have a slight veil of fog, look for the trouble in your lens. A dusty lens will give a scatter of light that will cause a general fog that is very destructive to negative quality.

If your lens is perfectly clean look for bright pieces of metal or wood inside the camera and go over these with a dead black paint. There must be no glossy surfaces inside the camera, no matter how black they may be.

When the fog extends over the margins of the negative that are protected by the rabbets of the plate or film holders it is evident that the fog is not a fault of camera or holders. The trouble must then be looked for in the dark room. Our method of determining whether or not any outside light reaches the film or plate while it is developing is very ingenious. Place a mirror in the position occupied by the developing tray and with all lights extinguished examine the mirror for any reflection of light. It may be that light from outside reaches the developing tray from a source which cannot be seen except from the position of the developing tray. If this is the case such light will be seen in the mirror.

If the dark room light is unsafe the passage of actinic rays can be detected by laying an unexposed plate in the tray in total darkness, laying one or two coins on it at the same time. If the dark room light is turned on and the developer applied, the presence of fog should be detected in five or six minutes by the production of outlines of the coins when they are removed.

Tests for the safety of a dark room should always be made at the distance from the light at which the developing tray is used. A light may be safe for developing at a distance of four feet and altogether unsafe at two feet. In fact there is no light that is perfectly safe for an indefinite time. For this reason the safest light filters, Wratten Safelights, have been given a standard of safety which permits of a plate being developed at three feet from the light.

Portrait Film Negative, Artura Print By L. J. Buckley Binghamton, N. Y.

Portrait Film Negative, Artura Print By L. J. Buckley Binghamton, N. Y.

October Practical Suggestions StudioLightMagazine1919 237Portrait Film Negative, Artura Print By L. J. Buckley Binghamton, N. Y.

Portrait Film Negative, Artura Print By L. J. Buckley Binghamton, N. Y.

Eastman Portrait Film Negative, Artura Print By Blank & Stoller New York, N. Y.

Eastman Portrait Film Negative, Artura Print By Blank & Stoller New York, N. Y.