On 6 February 2012 07:08, P. J. Alling <webstertwenty...@gmail.com> wrote: > The 150mm was not a popular focal length, (more expensive a 135, which > everyone and his brother just had to have and an odd icky focal length), >
Back in the dawn of photography lenses were simpler beasts and cameras all used plates or sheets of glass, copper, tin or paper, and later on film. Many sizes were popular for various uses, see http://en.wikipedia.org/wiki/Film_format#Single_image It followed that many different lens focal lengths were required for each format to have a normal lens that was the best natural performer for that image size. To shoot longer or wider a photographer simply fitted his camera with the normal lens of a larger or smaller camera. Wide-angle shooting was a problem, because to make a smaller camera's normal lens work well on a larger camera it needed to be stopped down considerable, and still wasn't very good. Eventually the lens designers got better at their craft and we got decent wide angle lenses as well as long focus and portrait lenses that were specialized to their tasks. Which is all a long-winded way of saying that "odd icky focal length(s)" are mostly the normal lenses of forgotten formats. 120mm is the normal lens of a 3in x 4in camera. 135mm is the normal lens of a quarter plate camera. 150mm is the normal lens of a postcard camera. 135mm lingered as a popular focal length. And then someone at Pentax felt a need to revive some less popular focal lengths, and we got 120mm and 150mm Takumars and Pentaxes. regards, Anthony "Of what use is lens and light to those who lack in mind and sight" (Anon) -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
