The Dictionary Of Photography

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

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The action of a condenser is well shown in the following diagrams. Let R be the light emitting rays which pass through the negative on slide p, and let o be the objective or projecting lens. It will be seen from this that practically very little light passing through the slide reaches the objective; but by placing
Fig. 30.
a condenser between the radiant and slide it will be seen that it refracts light which would otherwise be lost, as shown by the dotted lines, and condenses it, so that it is utilised by the pro-jecting lens. Simple lenses could be used for condensers, but on
Fig. 31.                                                   Fig. 32.
account of their great thickness they would be liable to crack, and there are other objections. It has been the custom, there-fore, to split the single lenses, and mount the two lenses with their convex surfaces nearly touching as in fig. 31. A further improvement, suggested by Mr. Traill Taylor, was the form shown in fig. 32, which consists of a meniscus lens and a