J.H. Dallmeyer London 6" (152mm) F3.2 Antique Brass Petzval Lens C1862 RARE

J.H. Dallmeyer London 6" (152mm) F3.2 Antique Brass Petzval Lens C1862 RARE

Serial No. 4154

This is a very early petzval lens from J.H. Dallmeyer London within first 2-3 years of production. What makes this one special is that is has an anomaly in that it has not been cut for waterhouse stops(neither the outer barrel or inner barrel & with no provision inside for stops) It's unusual especially since the maker's name is engraved in the usual place, almost like it was originally intended to be cut but never was for some reason. Perhaps a special request/order. Unfortunately it's too early a lens to be in the Dallmeyer archive so no confirmation can be had. I have far earlier lenses from Dallmeyer and they are all cut for waterhouse stops so it's a real mystery but an intriguing one at that!

Otherwise the specs are exactly that of Dallmeyer's early 1B (ordinary) portrait petzval lens. i.e same size glass, same height, focal, speed & coverage.

Focal length: 6" (152mm) Measured from centre of barrel to ground glass screen when focussed at infinity.

Focal length measured from back lens element to ground glass screen when focussed at infinity is 4.25 inches.

Speed: F3.2

Design: Petzval - front lens is a cemented achromat whilst rear consists of two elements, flint+crown set in their own individual housings.

Coverage: Covers(illuminates) 5x4" with some small vignetting in far corners when focussed at infinity.

Cosmetic condition: In good cosmetic condition especially considering age. Still retains most of it's original lacquer.