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

[Brian C. Miller]

Something's always bothered me about that photo. The lens looks like it was added in a retouching job. Maybe the actual lens didn't look that impressive, or maybe it wasn't mounted when they took that photo.

The lens was real, and so was the photograph it made, for a contact print. What you see in the photo is a problem with the early emulsions (and of digital today), is that of what happens with bright objects when the emulsion has a limited range. The lens was brightly polished brass, so in the photo it looks really weird. It's like when a current digital sensor gets that magenta shadow around bright chrome. The only thing they could have done would have been an early version of HDR: expose for the people, and then make another exposure for the lens, and then put the two together in the darkroom.

[Peter Gomena]

I've always wondered if any of the contact prints from this gigantic camera still exist. I kind of doubt they would have been shipped back from France, but surely the railroad company must have had an extra made for "home" use.

[Jac@stafford.net]

The lens was brightly polished brass,

I believe it was painted black.

[Steven Tribe]

I made a mistake in transcribing Corrado's book text.

It is indeed an aplanat - not an aplanatic.
So 4 pieces of 1 meter diameter glass - 8 glass surfaces to work and 2 balsam joins to make.

[E. von Hoegh]

I made a mistake in transcribing Corrado's book text.

It is indeed an aplanat - not an aplanatic.
So 4 pieces of 1 meter diameter glass - 8 glass surfaces to work and 2 balsam joins to make.

An Aplanat working at f2 sounds incredible, are there any illustrations?

[BarryS]

The first photograph is an obvious (and bad) retouching job. The second photograph might show the real lens or it might be another retouching job. I have plenty of experience with orthochromatic emulsions and from the earliest photographic processes, it's been possible to take photos of brass lenses in the sun.

[Steven Tribe]

No, Corrado was writing in a section with the alphabetic listing of minor French lens makers (he has a separate listing for Berthiot alone without the other partner).

He has a direct reference to the later listed numbered references (full academic style) which is the Industry report from just after the EXPO 1900.
Have searched a bit for it (photos etc) but only found who got gold and silver medals etc.

I'll drop him a line if anyone wants more information?

[E. von Hoegh]

I'm curious.

[Steven Tribe]

Email sent to Italy!

[Steven Tribe]

And a reply from Corrado, which includes the reference he gave.