a different spin on things

Goerz Hypergon extreme wide angle lens

Toronto. One serious issue with extreme wide angle lenses in the days of big cameras and film or glass plates was light drop off in the film (or plate) corners. Expose for the centre, and there was serious vignetting. Expose for the edges, and the centre was burnt out.

In the beginning of the last century, Goerz found a solution. They mounted a tiny fan on the front of some of their  Hypergon lens as I wrote in this February 2003 article.

Like all extreme wide angle lenses, sharply curved meniscus glass was positioned around a central stop giving both the extreme wide angle of view and severe edge drop off of light. (see Kingslake – A History of the Photographic Lens, pp54, 55). To use the Hypergon, the tiny front fan was spun by air propulsion for part of the time and then flipped out of the way to expose the centre rays previously blocked. Ratio was critical. Aperture was tiny, lens was very slow. Awkward or what!

A tripod and long exposure were mandatory – no instantaneous shots here! Of course a smaller  plate could solve the problem of edge vignetting, but you would lose the extreme wide angle point of view you paid for with the Hypergon…

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