Failure to take this change of stop values into consideration has been responsible for much of the under-exposing of copies. Even a modern lens with its focal length given and its stops plainly marked is,puzzling enough to a beginner, but if he is required to work with a lens of unknown focal length and stops that are not marked, he can not be expected to solve the problem.

The best method of determining exposures under such conditions is to make test exposures, and there is a right and wrong way of doing this. The main point is to get a difference in the exposures sufficiently great that it will be possible to determine the correct exposure with fair accuracy.

Place a kit in your holder that will take a small plate, say a 4x5, then push the slide in to a point where about one-quarter of the plate will be covered and make a pencil mark on the slide so you will be able to place it in the same position when the holder contains a plate and is in the camera. Mark the points on the slide where half and three-quarters of the plate are covered, and you are ready for your test exposures.

Supposing that the shortest likely exposure that might give you a result is fifteen seconds: Draw the slide to the first mark and give one quarter of the plate this exposure. Cap your lens, draw the slide to the point where one-half of the plate is covered and give a second exposure of fifteen seconds. You now have a strip of plate that has 15 seconds exposure and the remainder 30 seconds exposure. Draw the slide out to the third mark and make an exposure of 30 seconds, and you have exposures of 15, 30 and 60 seconds. Draw the slide all the way out and make an exposure of 60 seconds and you have exposed strips of 15, 30, 60 and 120 seconds. The plate should then be developed fully at normal temperature, 65°F., preferably in a tank, and not examined until fixed. With such a variety of exposures it is a simple matter to determine which one is most nearly correct, or to split the difference if one strip is under-exposed and the one next to it over-exposed.

Use a little material and spend a little time in making your apprentice efficient in any line of work, and in the end you will have saved time and material. If you are training an apprentice you will find that the more he learns the greater will be the interest he takes in his work. A little encouragement gives him greater incentive to do better work, and if he is at all industrious, he will soon become expert.

Knowing that you have such a workman and that you can depend upon him to produce results that will be a credit to your studio, you will naturally make an effort to keep him busy.

Many photographers have materially increased their business by specializing in copying and, in many cases, their customers have been those who have not been accustomed to visiting a studio. If they are pleased with the treatment and the work they receive they are the best of prospects for new business. It is the new business that makes your business grow.

Every time you encounter halation Every time halation ruins a plate result just remember:

Eastman Portrait Film Negative, Artura Print By Pasquale S. Culotta Baltimore, Md.

Eastman Portrait Film Negative, Artura Print By Pasquale S. Culotta Baltimore, Md.

Eastman Portrait Film Negative, Artura Print By Pasquale S. Culotta Baltimore, Md.

Eastman Portrait Film Negative, Artura Print By Pasquale S. Culotta Baltimore, Md.