20x24 lenses

[Tracy Storer]

Not long ago I practically gave away a 19.75" Eastman Anastigmat on Ebay. It covered 20x24. (admittedly, not the best at the edges, but still...) It wasn't one of THE lenses, so nobody seemed to care. The Fuji 600 C is as good as it gets and as new lenses go, it isn't THAT expensive if you want to shoot "big". My experience with single cells of shorter convertibles hasn't been that rewarding.(some cover, but with BAD edges) I tried a 600 Apo Ronar once, and wasn't satisfied with the edge performance near infinity(IIRC), but I had an 800 Apo Ronar, it covered fine and was one of the sharpest lenses I've ever owned, but at f/9 it weighed 8 pounds.

[Struan Gray]

Dialyte process lenses are specced for their intended application, which demands high resolution and low distortion over the whole field. The image does go to hell faster at the limits of the stated circle than with plasmats and tessars, and it doesn't improve so much with stopping down, but you can still squeeze a bit more out dialytes if you're not enlarging I have an 18" APO-Lustrar dialyte that covers 12x15 wll enough for contacts, despite being well outside its official image circle. Older lenses are more versatile for this as they tend not to have agressive field stops.

The APO-tessars are, well, tessars. I would expcet a 600 APO-tessar to cover 20x24, but perhaps someone here can confirm it.

The real problem is, as Tracy said, weight and bulk. APO-Lustrars are nice in that they often have slightly smaller apertures than more well-known lenses, and switched to aluminium barrels early on. The long ones are f16, but don't turn up very often.

[Mark Sawyer]

Tracy- I've had the same experience as you with the convertibles; the only one that was acceptable was the 14" (converted from 8 1/2") Acuton/Caltar, which looked "okay" on 8x10 contacts. The aperture can't be in the right place (all in front of the glass) on a converted lens.

Do you (or anyone else) know if the 21" and 22" Kodak copy lenses are the same design as the 19.75"? These seem like they'd be nice lenses, not too expensive, and come around once in a while...

Struan- I'd like to know the coverage on the 600mm tessars, too. I've seen several statements that Zeiss Apo-Tessars cover 20x24, but Zeiss made several (many?) different 600mm Tessars, and there are other 600mm Tessars out there too. (I lost a 600mm Russian Tessar to a snipe-bidder a few days ago...) Probably some do, some don't...

[Tracy Storer]

I don't know about the Kodak Copy lenses, maybe someone else does and will post. Not to state the obvious, but unless you're shooting near infinity a lot, you'll be able to get by with some very common and more affordable lenses, since coverage quickly increases as you focus on closer subjects.

[Mark Sawyer]

It would frequently be a landscape lens, so yep, it needs to cover at infinity.

Actually, I've tracked down two possibilities in my price range: a 530mm f/10 Cooke Apo Process Series IX, and a Kodak Ektanon 530mm f/11. Anybody know whether these would cover? The Mamut photo site lists the Ektanon as having 592mm of coverage, (20x24 needs 800mm). But it lists the Fujinon 600-C as having 486mm of coverage, and the Nikkor 450 M as having 440mm of coverage, and we've got first-hand knowledge here that they both cover when stopped down.

[Eric Leppanen]

Mark,

The Fuji 600C is actually rated at 620mm of coverage: www.thalmann.com/largeformat/c.htm

Of all the modern lens manufacturers Nikon is generally by far the most conservative regarding image circle ratings. I'd be careful when extrapolating Nikon ratings to other lens manufacturers and designs.

[Mark Sawyer]

Thanks for the info, Eric. About all I can extrapolate from figures I've seen so far is that coverage numbers from different sources don't agree with each other or with what a specific example of a lens actually does. I don't think any of these lenses were meant for 20x24, but cover sort of "by accident." The best info is from people who have actually used a lens on 20x24, but that's pretty rare.

Anybody know what the coverage is for 600mm Aero Ektars and Aero Tessars? I've been seeing a few of these around fairly cheap lately...

[Ole Tjugen]

APO-Tessars generally have less coverage than "regular" Tessars, 40 to 45 degrees according to my 1910 literature. This may be due to stricter tolerances, after all nobody in their right mind would use one for general shooting in 1910 - at a price of 10 to 100 times that of a perfectly good anastigmat!

A propos aero lenses: Anyone know anything about Schneider Aerotar's? I just won 7521056507 on ebay...

[Dan Fromm]

Ole, when you have y'r Aerotar in hand, tell us about it. It is pretty much a mystery lens AFAIK. As in, they're around but there's no easily-found information about 'em. They seem to have been made between the wars.

Mark, the Vade Mecum says they were used on 9x18 cameras. That's inches, not cm, and the cameras used 10" roll film. The VM adds that the AeroEktar and AeroTessar were made to the same specification.

[John D Gerndt]

I have a 530mm f11 Copying Ektanon and 24 inches of image is all you'll get out of that. The older anstigmats are rumored to have better coverage but I have not tried one.

Remember that the Dagors were copied a lot, you could look for one, though I don't know how many were copied in 19 inch form...

Cheers,

John