mrcallow said:
Good Day,
I am hoping that the lens experts out there can give me some information on a 18 by 22 Dallmeyer Rapid Rectilinear Lens circa 1868. I have seen about 60 prints made with this lens and would like to separate the the characteristics of the lens from the shooter.
The Rapid Rectilinear was invented in 1866 by J. H. Dallmeyer, a few weeks after the design of the practically identical Aplanat by Dr. H. A. Steinheil. So the two inventors eventually (after much heated debate) decided to share the invention - and the market. Eventually just about everyone made a RR - or an Aplanat - under some name or other. Some historiand assume that Dallmeyer combined two "landscape" meniscus lenses to see if he could get rid of the distortion while Steinheil (and his friend von Seidel, a mathematician) had calculated it.
This was the first rectilinear lens of usable max. aperture, so even if f:6 is not particularly "rapid" today it was a breakthrough at the time, and the name is quite justified.
From now on I'll use "Aplanat", partly because it's easier to type, partly because that's what I own...
The Universal Aplanat was the "standard" lens; f:7.2 was a common specification. Sharp image circle was about 30 deg. at full opening, increasing to as much as 70 deg. on stopping down. By placing the elements closer to the stop the coverage was increased but the aperture reduced - Weitwinkel Aplanat lenses were typically no faster than f:18, but compensated with coverage which could exceed 100 deg.
There were also "Portrait Rectilinears", or "Portrait Aplanat", "Aplanat Ultrarapid" and so on with max aperture as low as f:3.5 but very poor sharp coverage, about 15 to 20 deg.
In my collection is a Steinheil "Patent No.6", which to the best of my knowledge is an Aplanat. If so it must be one of the very earliest ones - it's certainly still a very fine lens!
Sources: Rudolf Kingslake, "A History of the Photographic Lens", 1989;
Hans Schmidt, "Photographisces Hilfsbuch für ernste Arbeit", Berlin 1910;
and my own collection...