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Tripod Mount Clarity Issue?
Re: Mr. Spada in the December 2009 issue of Shutterbug, the apparent lack of “clarity” he observed could also have the results of diffraction. Even a lightweight tripod, when weighted down as he described, should have given satisfactory results with the mirror locked up. I’m assuming he used a cable release or remote. I have a suspicion that he made the 1⁄250 sec test exposure at one f/stop and the 1-second exposure at a much smaller f/stop (maybe f/22 or higher) and the apparent lack of sharpness was the result of diffraction.
A good example of this can be seen at: Scroll down the page to the table and select a camera. Then move your cursor over the different f/ numbers and you will see how the size of the diffraction spot (airy disk) changes. Read the discussion in the paragraphs below the table to understand the science at work here.
Dennis Fisher, Consultant
Range Optical Systems, Design & Applications
via e-mail

This is a good explanation of what might have made our reader question the sharpness of his lens when used on longer exposures when mounted on a lightweight tripod. As you suggest, he probably used vastly different apertures, especially if conducted under similar light levels. Thanks for also providing a website that can provide data for different f/ numbers being used.

Tech Pan Processing
Q. I have been sent two 120 rolls of Kodak Technical Pan 6415 films from Pakistan. They apparently contain images of sentimental value. I have not been able to find anyone locally to process this film (it seems that Kodak no longer makes it). Would you know of anyone who could help?
Khalid Ikram
via e-mail

A. I have never processed Kodak Technical Pan film myself, so I called the Kodak Professional hotline (800-242-2424, ext. 19) and found that to obtain the utmost quality from this older black-and-white film it should be processed in Kodak Technidol Liquid developer, which is now discontinued. They also told me that this film can actually be processed in any conventional black-and-white film developer and since you are primarily interested in the images, and not necessarily achieving the top quality in this very specialized film, regular processing should be OK. In the Lab Showcase directory published in every issue of Shutterbug there are many labs listed, several of which indicate they specialize in black-and-white processing. Several I found in the current issue are: Black & White Custom Darkroom & Digital Services (; (928) 379-0426), Labwork (; (216) 621-7567), and Specialty Color Services (; (800) 207-7927). I suggest you contact each of these labs and ask if they can process and print your 120 Technical Pan film. Since these are images of sentimental value, be sure they can do the work before actually sending the exposed film to any of these labs. You should also indicate whether you want a contact proof sheet or prints from each roll of negatives.

Leica Values
Q. Could you help me price a camera I received from my uncle? It is a Leica camera that I believe to be a Model IIIb or IIIc.
Bill Rouse
via e-mail

A. The 11th edition of McKeown’s Price Guide to Antique & Classic Cameras 2001-2002 indicates the Leica IIIb (1938-46), the last prewar Leica, is valued at $300-$450. A black version is quite rare and commands over $30,000. The Leica IIIc (1940-46) has a price of $600-$900. There were military versions of both cameras that are valued considerably more. This book is several years old, so I don’t know how the market price has fluctuated since it was published. Of course the condition of the camera will affect the value, but it would seem you got a nice camera.
You indicated that you were not sure whether your camera was a Leica IIIb or IIIc. You can obtain some helpful tips on identifying different models of Leica cameras (too lengthy to cite in this reply) in a book titled Identifying Leica Cameras by Chester Sartorius that’s published by Amphoto Books (see You also might want to explore further about Leica cameras at the Leica Historical Society of America website for Leica enthusiasts at: