Special Lens And Recorded: However, although a long focal length lens is mandatory, it need not be expensive. The utmost of critical sharpness in a portrait lens is not necessary, or even desired, since considerable diffusion can be tolerated in portrait negatives. Your lens needn't be in a shutter for strictly studio portraits, either. A lens in barrel is perfectly satisfactory, since you can provide yourself with a simple Packard shutter to use behind the lens. Many portrait men actually prefer the Packard to the more costly between-the-lens shutters.
The automatic cameras which are suitable for this project are designed primarily for identification work, and it is possible to put an identifying number on each negative. Instead of using a number, however, it is better to use the same space to record the full name of each pupil. This is done by having the child's name typewritten on a card which is inserted in a slot in the camera. At the time the picture is taken of the subject, the name is photographed by a special lens and recorded on the edge of the film. Such a Camera makes it almost no task at all to fill reorders which will come in when the parents have seen the pictures.
The first lens designed specifically for photographic purposes was Petzval's 1840 portrait lens. The images formed by this lens showed great loss of definition at the corners of the plate-a fault more theoretical than practical in portraiture, where edges mattered little. For outside work, however, particularly in photographing architecture, a lens with a flat field was desirable; and one free of spherical aberration, which caused straight lines to be imaged as slightly curved, was essential.
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Photography
