ve Fapers on Photography. 19 If we place our ground-glass screen at A it is evident that rays from B will not be represented by a point but by a small circle but if we place a stop in front of the lens it will cut off t he outer rays proceeding from B, and therefore the outer rays of the cone of… … It will be seen that, using the same lens, to halve the diameter of the circle of confusion, we must halve the diameter of the stop, thereby reducing the light to a fourth of its former intensity. Again, if we compare two lenses— one, say, of 4, one of 8 in. focus — and if we suppose our diagram to…
Photography
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