This section is from the "Studio Light Incorporating The Aristo Eagle - The Artura Bulletin 1917" book, by Aristo Motto. Also see Amazon: Studio Light Incorporating The Aristo Eagle - The Artura Bulletin 1917.
The men in closest touch with the photographers and with the greatest number of them are the demonstrators, and in a conversation with one of these demonstrators the other day I was told of what appeared to be an epidemic in his particular territory.
A great number of photographers had complained of their negatives lacking in brilliancy, in fact they were so foggy looking that in most instances where the blame had not been laid on the plates, a search had been made for pin holes in the bellows of the camera or for reflecting surfaces that might scatter light and produce the effect. In every instance, however, the trouble was corrected by cleaning the lens.
It seems strange that so common a cause for trouble should be so easily overlooked, but in several cases the trouble was found even where the cleaning of lenses was a regular habit.
Unusual atmospheric conditions had caused this trouble, demonstrating the fact that a regular habit of cleaning lenses is not sufficient to prevent trouble if the cleaning is not done often enough.
The demonstrator showed me a number of interesting pictures of the "before and after" type that he had made to show the effect of dirty or smoky lenses. An exposure was made on one end of the plate, the portrait being vignetted at the shoulders. The lens was then cleaned, the plate turned end for end and another exposure made through the clean lens.
The difference between the two results was the difference between a good and a bad negative. It is hard to realize how so much damage can be done to the quality of a negative by a coating of dust over a lens surface, but a demonstration shows it very clearly.
The lens surfaces gather moisture and dust particles until there is a coating over the entire surface that more or less effectually scatters and diffuses the light, giving very much the same effect as fog.
The usual way of cleaning a lens is to brush or wipe the dust from the outer surface assuming that the surface inside the camera is sufficiently protected to remain clean. The fact is that dust readily collects inside the camera box and every time the bellows is drawn out and moved back and forth in focusing this dust is stirred up and must settle down again, the lens getting its full share, especially if there is moisture on its surface.
Look over your lenses carefully and keep them clean. And if the air is moist you will have to look them over more often than if it is dry. It isn't much trouble and clean lenses have everything to do with clean results.
Artura Iris Print, From Eastman Portrait Film Negative By Barnum Studio Cincinnati, O.