----- Original Message ----- From: "Gary W. Marklund" <Gary@xxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx> Sent: Thursday, December 21, 2006 6:31 AM Subject: [pure-silver] Re: Bulb for Focomat IIc
At 12:26 AM 12/21/2006, you wrote:Quoting "Gary W. Marklund" <Gary@xxxxxxxxxxxx>: snip> My 1C calls for an Opal 75 watt. So, I guess the 211 is > what you want. The Ic does not call for 75w (earliest documentation suggested 75w given heat and the very long exposures demanded by then contemporary papers) but is (in general) suitable also for 150w. Later versions (more elongated, egg like shaped, versus nearly round) were explicitly also for 150w and most that saw commercial action got 150w bulbs (time was and still is money).My "manual" is a downloaded reprint of a 15 page document titled "focomat Ic Instructions for Use", Ernst Leitz gmbh Wetzlar. Back page says Branch Works: Ernst Leitz (Canada) Ltd, Midland-Ontario. List Photo No. 6095a/Engl. X/52/LX. Printed in Germany K. Waldschmidt, Wetzlar. Topic C on the top half of page 6 states "The 75 WATT BULB normally supplied and used in conjunction with the condenser lens yields a diffused illumination advantageous for miniature negatives as blemishes or dust particles on the back of the film are prevented from appearing on the picture and harmonious enlargements are obtained." Next to that paragraph is a diagram of the lamphouse showing a light bulb with the inscription "75 W Opal Lamp". Probably a misprint or it got scrambled during the download, sorry. Gary
I'm not sure which part of this is the suspected misprint. FWIW, the PH-211 (75 Watt) and PH-212 (150 Watt) are the same size (I have both for my D2V). The type numbers were originally General Electric designations but havebecome sort of generic. I do not often use the 212 lamp in my enlarger because of the heat.
Most so called condenser enlargers are actually partially diffusing due to the use of a large, diffuse surface, lamp like the 211/212. Some condenser enlargers use true specular sources and are completely collimated. These have the advantage of producing very sharp images but are very fussy. Any blemish on the original is very much exagerated; a means other than the lens diaphragm must be supplied to regulate intensity; the source must be focused for each change in magnification; the source also exagerates contrast substantially. Such sources are used mainly for special purpose printing such as electron microscope negatives or very large pictorial prints. --- Richard Knoppow Los Angeles, CA, USA dickburk@xxxxxxxxxxxxx ============================================================================================================= To unsubscribe from this list, go to www.freelists.org and logon to your account (the same e-mail address and password you set-up when you subscribed,) and unsubscribe from there.