Mysterious: "Flat lens(element) " ?? Does that exist ?

[rfshootist]

Hi to all,

mysterious: in a German Atget book I read that the 19th century LF camera of Eugene Atget had a " Flachlinse". "Linse" in german is NOT the English "lens" tho ( "Objektiv" in German) but a single lens element.
So "Flachlinse" could mean this old camera had a lens with one "flat" element.
Has anybody a clue what could be meant here ? Backside, frontside flat ? And what effect does such a lens have ?
I know only flat front elements like the CV 4/25 has one.
AFAIK it cannot be a translation from an English term, a flatlens does not exist in English, at least not in the context with historic LF cameras ?

Thanks for all input !

bertram

 

[JG Motamedi]

If he used an achromatic landscape lens, which is very possible, it would have one flat side and one rounded. If I recall correctly, if the round side faces out it has field curvature but is sharper in the middle, if the flat faces out it would have a flat field, but require stopping down for sharpness.

 

[rfshootist]

If he used an achromatic landscape lens, which is very possible, it would have one flat side and one rounded. If I recall correctly, if the round side faces out it has field curvature but is sharper in the middle, if the flat faces out it would have a flat field, but require stopping down for sharpness.

Interesting, thanks ! Would mean "achromatic" was the poor journalistic translation of "flat".
I haven't seen field curvature in his photos, most of them are architectural and should have made any curvature visible. Must check if his landscapes are getting soft towards the edges. The lens was relatively wide but I am not sure if he could stop down at all btw.

Regards and thanks again !
Bertram

 

[Marc Leest]

Could he mean 'corrected for pincushion/barrel distortion'' and hence given a flat projection ?

M.

 

[David A. Goldfarb]

In German of the period, though, you also have trade names like "Protarlinse," so maybe it's a particular version of the Rapid Rectilinear.

 

[Ole]

Or it could be an Aplanat - the first good approximation to a flat image field. Practically identical to the Rapid Rectilinear...

If the shots are architecture, with a seemingly flat field, good sharpness and so on, in the 19th century that's almost certainly done with a good Aplanat. The first Anastigmats were less sharp, and landscape lenses show obvious field curvature and/or distortion. I have samples of all, and the differences can be seen on the ground glass

 

[rfshootist]

Or it could be an Aplanat - the first good approximation to a flat image field. Practically identical to the Rapid Rectilinear...

If the shots are architecture, with a seemingly flat field, good sharpness and so on, in the 19th century that's almost certainly done with a good Aplanat. The first Anastigmats were less sharp, and landscape lenses show obvious field curvature and/or distortion. I have samples of all, and the differences can be seen on the ground glass

Ole, David and Marc,

you all know more about lens history than I do, what I can offer are some examples to check. There are other Atget nuts like me re-photographing his places and maybe the photos say more aboot what the lens was. Maybe an Aplanat.

It's been a french camera from the 19th century, as it is said.

http://www.art.usf.edu/marcus/atgetrephoto2.html

http://www.lensculture.com/rauschenberg.html

Maybe this helps ?

Best,
Bertram

 

[David A. Goldfarb]

He's using a lens with a pretty flat field and not so great coverage, causing the vignetting that one often sees at the top of Atget's photographs with the use of front rise for tall structures, which would most likely indicate some version of a Rapid Rectilinear or Aplanat. By the late 1890s he could have switched to a wideangle design that would cover the format, but apparently, Atget wasn't an equipment junkie, and he stuck to the same setup.

 

[JG Motamedi]

... http://www.lensculture.com/rauschenberg.html ...

Thanks for this link.

Regarding the lens, following David's comment I don't think he was using an achromat since his photographs often show vignetting from front rise and an achromat would provide quite a bit of image circle although with very little of it sharp.

That said, as I recall he was not using the best or most up-to-date equipment, so using a landscape lens from the middle of the 19th century would not be out of character, but I think the photographs prove that he was using something more "modern"; an RR or Aplanat.

 

[phfitz]

Hi there,

rfshootist; I think the reference 'flat lense' is compared to the petzval type lenses which have a very curved field and were popular back then.

The photos look like aplanat or RR, protar and dagor would have more coverage and no black corners.

Good luck with the hunt

 

[rfshootist]

Thanks to all !

This has been a very intersting trip back to the early lenses, my knowledge at this point is near zero. Seems the real historic competence is at APUG, I could not get any info about this issue at any other forum.

Maybe I should deal more with those 19th century technologies, good idea fore the next birthday present )

Atget indeed wasn't a gear junkie, to say the least. He was well known downtown, crossed the city of Paris fromm Montparnasse to Montmartre and from Bois de Boulogne to Belleville, a much too slim old much loaded with tha huge camera, tripod , and a pile of glass negs.
It is said that another photog (maybe B. Abbbot) offered him once a Rolleiflex, one of the first on the market, 2 years before he died, because it was obvious that all that heavy stuff would kill that 70yo man.
He tried it out for a while and gave it back then and said "no, this is much too fast for me" )
He's been a man of the century he tried to conserve with his camera, the 19th century.

Best,
Bertram