CHAU3172   A rare official 1940s wartime dated letter and hand signed on headed paper from bird photographer and famous book author Eric Hosking who was one of the first professional photographers to make a living predominantly from photographing birds - In the letter he refers to his latest book and apologises for the delays from its publishing caused by the war - It is folded where posted otherwise truly outstanding condition, and being on his own headed 1940s paper you will never source better for lifetime authenticity.

"....To fully appreciate Hosking's black and white bird photographs taken during the 1930s and 1940s, it is useful to understand how difficult it was to take them. Every step of the picture taking process was totally manual, and success relied on in-depth knowledge, experience and calculation. Without through-the-lens viewing (which came later with reflex cameras), the camera was pre-focussed with a distance scale to where the subject was expected to be. The exposure was manually calculated, working out the best F-stop and shutter speed combination, and hoping that the light intensity did not change before the picture was taken. The light sensitivity of the film was very low, about ISO 10. (Later, ISO 400 - and above - film became readily available, allowing much faster shutter speeds). The emulsion was often on a fragile glass base. Only one picture could be taken before reloading with a fresh, unexposed plate. Film holders could only be loaded in complete darkness, necessitating a light-proof changing-bag. It was quite common to have only 12 exposures for a day's photography. The glass negatives had to be developed in the darkroom at a later date and then printed as positive prints...."