It is advisable when first attempting to enlarge to make one or more test strips to determine the proper duration of the exposure.

A strip of Bromide paper one or two inches wide and long enough to extend diagonally across the important part of the image, will be sufficient.

Correct exposure depends on several factors ; the intensity of the light, the density and colour of the negative, and the size of the enlargement.

The following exposures on " Kodak " Velvet Bromide are suggested as a guide with a 100-watt lamp and a negative suitable for enlarging :

Magnification 11/2 times, 15 seconds.

Magnification ; ; ;21/4 times 35 seconds

Magnification ;31/2 times 70 seconds

Do not attempt to count the time ; use a watch or clock.

The first test exposures will be purely arbitrary. With a 100-watt gas-filled lamp, a negative of average density and enlarging 11/2 times the linear dimensions of the negative, it is suggested that a test strip should be made as follows : Cover up two-thirds of the strip with a piece of card and expose for five seconds ; move the card and give the middle section five seconds, making ten seconds for the first : then remove the card entirely and expose a further ten seconds. The fully exposed strip will now contain three different exposures-the first section twenty seconds, the middle section fifteen seconds, and the last section ten seconds.

If a 60-Watt lamp is used, make the exposures twice as long. With a 150-Watt lamp, make the exposures shorter by about one-third, and with a 200-Watt lamp make the exposures about one-half of those suggested when the 100-Watt lamp is used.

If more than one print of the same size is to be made from the same negative, leave the steel bar nearest to the standard in position, after the first exposure has been made, and the light has been changed from white to orange by means of lever M, lift up the other bar, draw out the Bromide paper, insert the fresh sheet under the edge of the first bar, replace the second bar as before, and all will be ready for making the next exposure. By this method all succeeding exposures will be in the same position on the paper as the first print made.

Develop the test strip, usinor " Kodak " Special Developer at a temperature or 65-68° F. (18-19° C.) prepared according to the instructions supplied with it. " Kodak " Special Developer gives fine black tones and clear high lights and is supplied in a concentrated solution, as well as in powder form in packets and glass cartridges. Full instructions for developing are included in each package of Bromide paper. When a Bromide enlargement is being developed, if it has been correctly exposed, the image will appear in 15-20 seconds, developing brilliantly and attaining full strength in about 90 seconds. If these test exposures are all very much over- or underexposed, make another set of test exposure, shortening or lengthening the exposure as suggested by the first strip. If the image comes up rapidly but dull and full of detail in the high lights, it has been overexposed ; if weak and without detail, it is under-timed. Under different conditions the time required for exposure varies from about ten seconds to about five minutes, according to the light used, the density of the negative, the size of the enlargement, etc. However, a few trials will narrow the exercise of judgment down to the density of the negative, and the making of correct exposures becomes a simple matter. The best negative for enlarging is one neither too dense nor too weak ; it should have full detail in the deepest shadows (clearest portions of the negative) yet not be too dense in the high lights (blackest portions of the negative).

When enlargements of different sizes are being made it must be remembered that the intensity of the light decreases as the camera is raised or moved further away from the paper, and it will therefore require a longer exposure for large-sized enlargements than for small enlargements.

The lens may be easily removed for cleaning by unscrewing it.

Diffusion

It a diffusion or softening of the lines in the picture is desired, this can be readily obtained with the " Kodak " Auto-focus Enlarger, by using the Diffusing Disk. This is made of a specially prepared glass mounted in a cell, and when it is to be used it should be slipped over the lens of the Enlarger.

The Diffusing Disk does not change the focus, nor does it appreciably increase the length of the exposure ; it merely softens the lines of the image.

If only a slight diffusion is desired, leave the Diffusing Disk in position on the lens for about one-fourth or one-half of the length of time necessary for a correct exposure ; then remove the Disk and finish the exposure.

When the negative is very sharp, especially in the case of landscapes and large head and shoulder portrait negatives made with the " Kodak " Portrait Attachment, the soft effect produced by the Diffusing Disk will be found pleasing and artistic.