French madness - World's biggest (photographic) lens?

[Emmanuel BIGLER]

French madness? Here I am Thanks, Steven, for the document.

If I read well, the text in French speaks about lentilles aplanétiques which means : single lens element, or cemented doublet, not a compound lens like the Carl Zeiss Monster
What is unusual is the f/2 relative aperture of this single lens element (or doublet). I have no idea of its shape, so that is deserves the name 'aplanétique'.

Regarding big lenses, here is a wiki-list of biggest refracting telescopes still in operation, the champion is in Yerkes observatory in the US with a diameter of one meter = 40", although a bigger lesn of 1.25 meter = 50" in diameter was built in 1900 in France
http ://en.wikipedia.org/wiki/List_of_largest_optical_refracting_telescopes
The 1900 1.25 m telescope
http ://en.wikipedia.org/wiki/Great_Paris_Exhibition_Telescope_of_1900
But the f-number of those refective telescope lenses is around f/15, not f/2.
There is one refractrive telescope of diameter 80 cm, actually this is a twin-lens telescope (80 cm and 60 cm) in Meudon observatory near Paris, la grande lunette de Meudon, the Meudon 33-inch Great Refractor.
http://www.obspm.fr/histoire/meudon/meudon04.gif

This telescope was designed to make precise observations and photographs of planets. So the Meudon lens definitely deserves the name of photographic lens, although it is not a f/2.
This big telescope is currently under repair and as far as I've read, will be available for the public in the near future.
Hence optical technology of the 1900's was able to fabricate glass lenses of at least 40" in diameter, and the instrument still exists in Yerkes observatory; the record being 50" and well-documented although no longer existing.

[Steven Tribe]

I read through the text and was sure aplanétiques was the equilavent of aplanatic, rather than aplanat as translated by Corrado.

[Emmanuel BIGLER]

Yes, according to this French authoritative on-line dictionary, http ://atilf.atilf.fr
aplanétique is simply a French spelling for the original English word: aplanatic, and means: a lens corrected for spherical aberration.
Could be a cemented doublet like in refractive telescopes, but with a f/2 aperture!! I really have no idea for such a f/2 lens designed and fabricaded in 1900. 380 kg !!!
Could-it make sense that those crazy lenses were made as a technology demonstrator for the 1900 exhibition? Related to the crazy 50" refractive telescope?

[Steven Tribe]

Exactly, a National demonstration of technology and industrial know-how at the Paris EXPO of 1900!

[Michael Filler]

I would like to have seen the train. Anyone know of an image available online?

[hiend61]

A few years ago, in the 90's, an Arab sheik had Hasselblad and Zeiss make a one of a kind lens for his nature work. That lens was hung over the Hasselblad booth at Photokina and it was longer then the showcase! And it fits a recent camera!

The sheik is HM Hamad bin Khalifa al Thany, who is the present Qatar sovereign and an absolute photography entusiast and collector. He also ordered Leica to build an Apo telyt 1600/5,6 which he uses for nature photography.

[Andrew O'Neill]

BarryS and Vaughn, here is another image of that massive camera. The lens looks more realistic in this one.

[Jac@stafford.net]

The condenser lenses for my 8x10 Saltzman enlarger are something like 17 inches in diameter. It never occurred to me to see if they could be used as a lens.

[CCHarrison]

Ok, I'll play.... here's a shot of the Alton Camera with the text about the lens.

Dan

[Dan Fromm]

Hard to know which Zeiss w/a lens was meant, but at one time they'd build 'em to order. See p. 60 for details. http://books.google.com/books?id=cnk...gbs_navlinks_s