The Dictionary Of Photography

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

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The Condensers. The function of the condenser is to collect the rays of light and refract them through the negative. The usual form of condenser employed is two plano-convex lenses placed side by side, with the convex surfaces nearly touching. The first question to decide in purchasing an enlarging lantern is, What size condensers are required ? as the size of the con-densers governs the price. It is a question which has often been asked by beginners as to what size condenser will cover a certain-sized plate. This is by no means difficult to decide. All that it is requisite to do is to measure the diagonal of the negative in question, and this diagonal will be the diameter of the required condenser. In practice it is always advisable to allow an extra quarter or half an inch where this does not add too much to the cost. Mr. Hughes has introduced a rectangular condenser. In selecting condensers, the most important points to note are, first, to see that they are as free as possible from colour; secondly, that the one next the negative is free from air-bubbles and striae; thirdly, that they are not set too tightly in their mountings, or when heated from the light they will crack.
Enlarging by Artificial Light without Condensers. This is a procedure which will commend itself to many an operator,
Fig. 56.
because the necessary apparatus may, in many cases, be con-structed from odds and ends in odds and ends of spare time. Thus we utilised an old square sugar case which cost 4^/., and the sheet-tin to line it yd., the lamp 15s., odds and ends, such as screws, ground-flashed opal glass, another 2s.; so that for i$s. an enlarging apparatus was obtained, which worked well for over two years. As condensers are usually rather costly, the follow-ing ingenious arrangement, which dispenses with them altogether