Meandering discussion about the utility of aerial lenses

[Dan Fromm]

GPS, you still can't read. If you could read, you'd have read that I found my 4"/2.0 TTH Anastigmat a better lens at all apertures down to its smallest (f/16) than my 101/4.5 Ektar.

[GPS]

Good for you, Dan.

[Asher Kelman]

In my experience, the commonly available affordable aerial lenses are no better (and sometimes even worse) than reasonably modern large format lenses, at least when used on regular view cameras. My guess is that we are already planarity limited on view cameras with the regular Plasmat or Biogon types. The higher MTF figures for aerial lenses may be fiction unless you use a rigid body and vacuum back - but under these conditions your average Symmar or SA should perform better as well.

Sevo,

Yes, the modern lenses in neat shutters are improved in DOF by a smaller aperture, but the resolution might very well be decreased from ~ wde-open. Can they get 90-200 lp/mm too under any conditions?

When you talk of the aerial lenses being planarity-limited that's for a certain format size. However, is there a format where one can get really outstanding above "modern normal" LF lens resolution with aerial lenses and have a practical system.

What about, for example, the Lamogens on 5x7?

Asher

[Ole Tjugen]

I should try my 500/5.5 Schneider Göttingen Aerotar one day. It's a heavy lens, from what I can see it's a 10/3 dialyte derivative. It should fit on my big Reisekamera, which has a front rigid enough for just about anything; with a reducing insert and 13x18cm film (or maybe 18x24?) it should work. If I can find some way of mounting a Packard shutter on or behind it.

[Dan Fromm]

Ole, thanks for mentioning a few practical problems of implementation.

Asher, the correct spelling is Lamegon. There's also a Super Lamegon. Where these lenses and others in their class really shine is in low distortion. They were made for photogrammetry, not for reconnaissance. Most lenses for military aerial cameras were made for recon and aren't really suited for photogrammetry.

As you can read here http://books.google.com/books?id=FSM...gon%22&f=false photogrammetry is done with terrestrial as well as with aerial cameras.

See this http://web2.ges.gla.ac.uk/~gpetrie/P...y_fulltext.pdf too, it may bring you back to earth.

My friend Charlie had at least three SMK-120s, each with a pair of 55/8 Lamegons. I think they've gone to Westlicht. Probably not for you, they shoot 2x3.

If you want really high resolution on-film, shoot 35 mm Agfa Copex processed for continuous tone,use a good grade of normal (for 35 mm still) lens, and meticulous technique. In other words, give up your fantasies and join the rest of us who do well to get 60 lp/mm on film consistently.

[Sevo]

Yes, the modern lenses in neat shutters are improved in DOF by a smaller aperture, but the resolution might very well be decreased from ~ wde-open. Can they get 90-200 lp/mm too under any conditions?

Some do - the inherent limits of the schematics tend to be a magnitude above the limit of production and assembly, so there is enough margin upwards if the elements are well matched and perfectly assembled and aligned. YMMV, though, makers specs usually put LF lenses in the 40-90 range, and in assembly they will go for a increased centre resolution above spec only if that by some lucky accident happens not to compromise the edge resolution and flatness of field.

When you talk of the aerial lenses being planarity-limited that's for a certain format size. However, is there a format where one can get really outstanding above "modern normal" LF lens resolution with aerial lenses and have a practical system.

If there are parallelity issues with the standards or planarity issues with bulging film, you will have to stop down to safe limits, where you'd lose the extra resolution to diffraction. Regular view cameras are designed that neither will affect focusing at f/5.6 or exposure at f/11 - you probably would have to go for a micro geared "digital medium format back" view camera to get the standards precision needed for 200lp/mm@f/2.8. And in any case you would have to use a vacuum back.

Besides, there is yet another issue. With movements adjusted under visual control, it is plain impossible to set up to the needed µm precision for a 200lp/mm resolution - to get movements with the latter, you either have to set up by measurements and calculation (hardly practicable even for still-life studio work) or the camera would have to be locked down plumb centre (after being precision adjusted in its neutral setting), which sacrifices the main point of using large format. As few of the more recent high end aerial lenses cover anything past 4x5, you are constrained to rather small formats too, and the total resolution across the image area is not that big even for a 200lp/mm lens - switching to 8x10 with a regular lens will deliver quite as high image resolution with extra DOF and without losing movements.

That is, using aerial lenses on a view camera for higher resolving power will rarely succeed in practice - but they may be an option if you need a low-DOF fast lens with LF coverage.

[Jim Galli]

Better than modern...........

Worse than modern.............

Some of us are working to a different goal than 68 line pairs in a millimeter. An uncoated Cooke Aviar with 8 air glass interfaces is not something that wins in a comparison to a multi-coated plasmat. But there are some who are bored to tears with multi-coated Plasmat look. So better & worse are highly relative terms to the user's intent.

Each lens must be used to make actual pictures and then evaluated for what it does or doesn't bring to the table relative to the user's vision, not line pairs per millimeter.

Process lenses and aerial lenses are not the first place I look for what I want a lens to do, but there are some exceptions. An f2.5 or 2.9 lens might have something for a 4X5 user that normally can't get that shallow a depth of field any other way. And the Aviar does have a pleasing look.........to me.

[Asher Kelman]

Better than modern...........

Worse than modern.............

Some of us are working to a different goal than 68 line pairs in a millimeter. An uncoated Cooke Aviar with 8 air glass interfaces is not something that wins in a comparison to a multi-coated plasmat. But there are some who are bored to tears with multi-coated Plasmat look. So better & worse are highly relative terms to the user's intent.

Each lens must be used to make actual pictures and then evaluated for what it does or doesn't bring to the table relative to the user's vision, not line pairs per millimeter.

Process lenses and aerial lenses are not the first place I look for what I want a lens to do, but there are some exceptions. An f2.5 or 2.9 lens might have something for a 4X5 user that normally can't get that shallow a depth of field any other way. And the Aviar does have a pleasing look.........to me.

Jim,

In 35 mm photography, I rarely go much more than f.18 to f 4.0. Almost never more than f8 as diffraction rears its head with the tiny sensels (ie pixels). With large format, as you know, my main interest is using the soft focus high speed lenses wide open for portraits.

However, where the object of the shoot is not an artistic rendering of a person or landscape, but getting exceptional detail, (not the magic of the PS945 or Visual Quality lenses), then either I can use existing lenses closed down on 8x10 to about f16 or a little more or, use my 4x5 reducing back and find lenses which although have small circles of coverage are far superior in resolution.

That's where my knowledge ends! What lenses, be aerial or modern would give any advantage over simply using what I already have in 8x10?

Asher

[Jim Galli]

Can't think of a one. The ones I saw in your kit were splendid choices. Except of course that one you just bought from me You'll have some fun with that at the portraits. jg

Jim,

In 35 mm photography, I rarely go much more than f.18 to f 4.0. Almost never more than f8 as diffraction rears its head with the tiny sensels (ie pixels). With large format, as you know, my main interest is using the soft focus high speed lenses wide open for portraits.

However, where the object of the shoot is not an artistic rendering of a person or landscape, but getting exceptional detail, (not the magic of the PS945 or Visual Quality lenses), then either I can use existing lenses closed down on 8x10 to about f16 or a little more or, use my 4x5 reducing back and find lenses which although have small circles of coverage are far superior in resolution.

That's where my knowledge ends! What lenses, be aerial or modern would give any advantage over simply using what I already have in 8x10?

Asher

[EdWorkman]

Dan
Thanks for your work and sharing of your experience.
About 10 yrs ago C&H surplus had several choices of aerial lenses, including a 48 inch, complete with massive cone. That one was priced at IIRC $1500, covered 9x18?
I did lose my sanity and bought a 36 inch tele for 9x9, replete with an almost impossible to use shutter. Last year i dug it out and mounted it on a 1x6, with a telescoping box for focussing, and the working parts of an Anniversary Graphic on the rear of that for 4x5. And another thing, I don't call it an optical bench, I call it , I call it "Hey-let's-see-if-this-monster-actually-can-make-a-picture".
It is so heavy and awkward that i haven't schlepped it out for exposures, but I recently got a pickup truck and have few excuses left.
Is it good? At a smallest hole f16 it will probly be dicey, and I could have hung around to find a lot smaller lighter better process lens, like a Wray, but then who would lead the fight against mental heath?