This is a Busch Rapid Aplanat 18" with an iris. As you can see from the link here to the Busch listing in the 1904 Kodak catalog, coverage is 10 x 13 wide open and 16 x 20 stopped down.
Dead Link Removed
The photos show that the brass looks pretty nice. There is supposed to be knob of sorts on the iris to move it from f8 to f64 but the knob is missing. The internal part the knob attached to IS there, and it is easy to move the iris with your fingernail or a pencil, etc.
The glass is good with some cleaning marks. There is about 1mm of white around the edge of the glass. It doesn't have the yellow look of separation but maybe it is some other kind of glue. It is only near the edge and small, but it didn't show in the photo, so I'll mention it. Normally, I'd remove the glass and give it a soak and a clean in Dr Bronner's, but I'm not sure exactly how to unscrew the glass on this, so will leave that to you if you want to do that instead of glass cleaner.
There have been a couple shorter Busch rapid aplanats listed here recently for $225-250 that only cover up to around 11x14. So, I'm thinking that this one should move quickly at $280 including US shipping. USPS money order preferred, but will take Paypal if you need to since my car needs rescuing from the repair shop...
Cheers, Richard
