Bausch and Lomb 30" E.F. Projection Lens

[Mark Sawyer]

If anyone's interested, it looks like you can pick up the 12" version for $45 (w/ s&h):

http://cgi.ebay.com/ws/eBayISAPI.dll...ype=osi_widget

[Gordon Moat]

Okay, after lots of digging, and going to the local library to look through Kinglake's tome of early lenses, I think my Holmes Booth & Haydens dates from near 1854 to 1858. It is somewhat similar to this completed auction item, though mine looks much better:

http://cgi.ebay.com/HOLMES-BOOTH-HAY...QQcmdZViewItem

Looking at the close-up image of the script on that one, mine is repaired around the focus knob mount with some sort of brazing/soldering. Seeing as how that one is No. 3025, and mine is No. 1875, I guess they made many of these lenses.

Kinglake indicates Petzval lenses are mostly f3.6. Using the rough calculation method, I came up with f3.4. I am going to try a Polaroid or two to figure out a workable aperture. Is it possible there was enough variation that a faster aperture was possible? Or should I stick to f3.6?

Also, Kinglake makes mention that a Harrison made Petzval was more desirable, and that 8800 of those were made. What that makes me wonder is how rare are these lenses?

Another thing is that Kingslake does not mention Bausch & Lomb as a Petzval lens manufacturer. Does that mean he missed that, or that all the Bausch & Lomb types were for magic lantern usage? The Bausch & Lomb 10" I just got definitely is a magic lantern type.

Last, I read that the spacer ring for the rear elements had to be within 0.5% correct dimension, or the focusing would be off. Do I have a reasonable chance of making/finding a replacement for my Bausch & Lomb, or ___________ ?

Ciao!

Gordon Moat
A G Studio