While mirrors are a not an uncommon photographic tool, their use is not explored in photography classes as often as their potential for creating unusual and highly effective visual statements would indicate.
In order to experiment with mirrors in a photograph they can be used as distortion producing devices or as sources for multiple images. Among the latter application the best known device is the kaleidoscope. This device can be used with a camera placed on a copy stand, aimed at live subjects or it can even be used in the enlarger.
The better the mirrors the better the final results typically are but even standard mirrors can serve especially for introductory experiments.
The best mirrors are those that are coated with silver or aluminum on the front rather than the rear, as most household mirrors are coated. The reason for coating on the back is to protect the fairly delicate metallic coating which might be exposed to bumps and scratches in a normal environment. Unfortunately these mirrors produce a weak secondary reflection from the front glass surface.
The first surface mirrors do not have this problem but they need to be handled with care. These mirrors can be obtained from a number of sources but one that is usually recommended is Edmund Scientific Company located in Barrington, NJ. The minimum size for use in front of a camera would be something like 4X5 inches. For use within a 2 1/4 x 3 1/4 or larger enlarger something a little smaller is advisable.
With a single mirror interesting results can be obtained by placing the mirror just below the edge of the lens and photographing the reflection of a scene in the mirror along with the subject itself. This creates an "instant" reflecting lake where there originally was none. This often lends impact to architectural scenes in particular.
Using two mirrors joined along one edge, interesting fractured kaleidoscopic juxtapositions of mundane objects can be made with a single exposure. By varying the angle between the mirrors the number and orientation of the multiple images is altered. Changing the direction in which the camera is aimed within the mirrored "V" formed by the mirrors is another way of altering the composition.
SLR cameras are obviously the camera type of choice for these types of manipulations. Built in meters are also most useful. Auto focusing may or may not be useful. It is advisable to use the lens in stop-down mode rather than at full viewing aperture because the edges of the mirror, and indeed the final visual quality of the image will be affected by the delineation of the mirror edges.
When working with these mirrors near a camera lens it is advisable to make sure the lens is protected with a clear protective or UV filter. This is to prevent accidental contact between the mirrors and the glass of the lens.
The placing of mirrors inside of the lens cone of enlargers was a method widely practiced by the renowned newspaper photographer Arthur Fellig, better known as Weegee. The placing of mirrors within an enlarger lens cone in this fashion needs to undertaken with care since there is a risk of dropping a mirror on the rear surface of the enlarger lens. Placing a protective filter over the rear of the lens's rear element is one way to avoid problems.
In this case the reflections are those of portions of negatives placed on the film carrier of the enlarger. Kaleidoscopic mirror arrangements or just one simple mirror will produce often startling and unplausible results.