Photography in the Studio and in the Field / A Practical Manual Designed as a Companion Alike to the Professional and the Amateur Photographer

by Edward M. Estabrooke

This apparatus, as will be seen in the engraving, is a camera with an unusually long bed-rail and bellows. It has a central frame which supports a lens, and a front frame supporting a negative, so placed for duplicating or enlarging, which is done by transmitted light.

The front is fitted with a kit of frames for the various sizes of negatives, from 3¼×4¼ to 8×10, or the largest size the box is capable of producing.

For copying by reflected light the lens is removed from the central frame and adjusted or attached to the front, where the negative is seen in the cut; and the picture to be copied is attached to an upright support (which is usually a part of the copying table or stand) p190 and exposed to the strongest diffused light available, the camera being adjusted squarely in front of it.

For duplicating or enlarging negatives the adjustment of the apparatus is as shown in the engraving. Such work being done by transmitted light. The negative to be enlarged is placed in the appropriate sized frame in front and the lens in the middle frame, which is placed nearer to the negative than to the ground glass. The conjugate focus is then found by drawing out the rear or ground glass focussing screen until the image is sharply defined on the glass. When the subject is sharply in focus, if the image is found to be too small the frame supporting the lens is pushed a little nearer the front; on the contrary, if the image is too large the lens is drawn back from the front.

For all such work the camera should be directed toward a window commanding a clear view of the sky, or if trees or buildings intervene then a sheet of tissue paper or a square of ground glass should be placed immediately in front of the camera and against the window. It will be found that Anthony's "mineral paper" is superior to either tissue paper or ground glass for this purpose, and should be used when it can be procured.

When it is desired to make a duplicate negative it is necessary first to produce a dia-positive or transparency; this is merely a copy of the negative (by transmitted light, or light passing through the negative to the lens) with its lights and shadows transposed or reversed. Great care must be taken to have this transparency in sharpest focus, and full-timed in exposure to secure line detail.

When a suitable positive has been secured it should p191 be dried and set up in the place occupied by the negative from which it was made, and with the film side toward the lens.

The process is now repeated, but with a shorter exposure, and the resulting picture is a negative (if well done) identical with the original.

The adjustment for size is, as before mentioned, effected by moving the lens support. If it is desired to enlarge, the lens is moved nearer the subject; if to reduce, move the lens back from the front. If the duplicate negative is to be of the same size as the original, the lens is moved to the position near the centre between the front and back, which will give the image on the ground glass the same dimensions by measurements as the original.

It will be observed that as there are two plates to be used the utmost care must be taken in the adjustment of the focus and in timing the exposure in both instances, to avoid loss of definition or quality.