The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Adiactinic                                                      Aerial Screen
preferably one of soft texture - cut several long strips of paper about half an inch wide. Using the lens tube as a mould, and some flour-paste, or starch-paste, form the long strips of paper into
- a ring of such thickness that its smaller diameter firmly grasps the lens thread and its outer diameter is a trifle larger than the flange to be adapted. The first strip of paper round the screw threads should fit rather tightly and be well pressed into the screw
threads. It will contract a trifle on drying. When the adapter is dry the outer thread may be cut by using the flange intended to be used. This, however, requires a little patience and care, and must not be attempted until the paper ring is quite dry and hard." A still more rapidly extemporised adapter is a strip of flat india-rubber cut to such a length as to form a ring with a butt join, which will lodge securely in the flange by virtue of its elasticity. When this kind of adapter is used it is generally best to allow the rubber to grip the middle of the lens tube, rather than the screw at one end.
Adiactinic. (See Actinic.) A term sometimes applied to red or yellow media for the dark-room window. No light is com-pletely non-actinic. (See Dark Room.)
Adon. This is a recent device by Mr. Dallmeyer. It consists essentially of a high-power telephoto combination, which is so set as to transmit parallel rays. If attached as a supplementary lens to the front of an ordinary lens on a " fixed focus camera, it gives an enlarged image without disturbing the focal adjustment. The elements of the Adon are, however, adjustable, so that it can be used with varying effect when the camera allows of focussing. In addition, the Adon can be used by itself as a high-power telephotographic lens.
Aerial Perspective. A term used to denote the idea of dis-tance in a landscape or photograph of the same, which depends upon the obstructive or dispersing influence of the atmosphere; although minute particles in the atmosphere, which particles themselves become illuminated and radiate light, are doubtless a factor.
Aerial Photography. See Balloon and Kite.
Aerial Screen. Transparent screens for lantern effects date from the time of Kircher, who used smoke. M. Philipstal gave