Single Achromat Lens

[Neil Purling]

A.K.A. Single View Lens.
I think these were the basic option.
A diaphragm in front of a single cell of 2 or 3 cemented components which have the concave surface towards the diaphragm.
Less astigmatism & field curvature than the Petzval. The problems being a max aperture of f11 and barrel distortion in the outer field.
Anybody used one of these ancient optics? They were still being offered by Beck in 1903 as seperate lenses as well as the cheap option in their "Frena" range of cameras.

[Ole Tjugen]

Well, yes...

It's the classic "Landscape lens". Slightly better than a simple meniscus, but only insofar as having less chromatic aberration. This doesn't seem like it would have mattered much in the days of monochrome plates, but it was really an immense improvement since it drastically reduced the difference between "optical focus" and "chemical focus" - i.e. "sharp to the eye" and "sharp to an UV sensitive wet plate".

Put two of them together, and you have a Rapid Rectilinear. Remove the front cell of a RR, and you have a "Landscape lens".

[Neil Purling]

The book by Conrad Beck mentions examples of single achromat lenses.
Beck made 3 variants: There is a wide-angle and narrow angle version.
You would need a 5" wide-angle type or a 10.5" narrow angle for a 4x5 plate due to astigmatism in the narrow-angle type.

[Ole Tjugen]

I have a "normal" J. Lancaster 5x4" Landscape Lens, and a Vade Mecum-like casket set with extra spacer rings for "normal" or "wide" configurations with both one and two cells. I have some negatives shot with these, too, somewhere...

[Maris Rusis]

I regularly use a 720mm f16 achromat lens I have mounted into a Copal#3 shutter for landscape work on the Tachihara 810 HD camera. The lens originally came from a cheap astronomical telescope and its centre sharpness is essentially diffraction limited but things get a bit vague off centre.

The worst aberration is field curvature which has a radius approximately equal to the focal length of the lens. A work-around is to line up the key subject half way to the far edge of the format, focus it there, then re-frame and close down to f64 or less. The depth of focus gained by stopping down covers enough optical sins for the resultant negative to be useful for contact work.

Not bad for a $20 lens.

[Jim Galli]

I have a really gorgeous 12" Darlot. What folks don't realize is that these are the poor man's "artistic" lens. If you free the optic from it's f11 - 13 restraint you will have a marvelous f6-ish soft focus lens. Indeed when all the Verito's and Pinkhams were gone it was this lens that Kodak adapted for a final "soft focus portrait" lens. Pinkham & Smith used these for their series V "Synthetic" as did Spencer Portland and other "soft focus" makers. Now the purpose built "soft" or "portrait" lenses may have deviated some from the original curvatures best suited for being sharp at f22. But the Darlot is just gorgeous used wide open. Emil just posted some shots done with one of these wide open and they are sublime.

I should add that all of the cheapest Kodak folders of the 1920's thru '50's used these lenses. The japanese way back in the teens were taking these out of their Kodak's opening them up and making soft focus pictures. The problem with most of the little Kodak lenses is focal length for our purposes. Most are about 4" which is too shallow even for 4X5.

[Ernest Purdum]

These are probably the easiest option for those who like to play optical games. Get a large achromat from www.surplusshed.com or other source, mount it in a piece of plastic pipe from the Home Depot, cut a couple of washer stops (you probably won't want to stop down much) and who knows. Maybe you'll wind up with the equivalent of the soft focul Kodak.

It's easy to figure the aperture for these. It's just the focal length divided by the actual aperture. The length of the pipe just depends on how much coverage you want.

[Larry Bullis]

These are probably the easiest option for those who like to play optical games. Get a large achromat from www.surplusshed.com or other source, mount it in a piece of plastic pipe from the Home Depot, cut a couple of washer stops (you probably won't want to stop down much) and who knows. Maybe you'll wind up with the equivalent of the soft focul Kodak.

It's easy to figure the aperture for these. It's just the focal length divided by the actual aperture. The length of the pipe just depends on how much coverage you want.

I have a really nice one from Edmund Sci of about 120mm, as I recall (and one of the identical design which I haven't mounted yet, 90mm), that I use with the 6x9 speed graphic (focal plane shutter is ideal). It was made as a riflescope objective; it isn't round, so the usual way of determining aperture would only work if I had a round aperture for it. Since I like the exaggerated spherical aberration, I don't do that, so f/value had to be determined through other means. Not difficult. This thing is every bit as good as the kodak version.

I've used a number of the folding Kodak cameras mentioned above (and ruined one by using it from my kayak in salt water). There is a restriction disk that limits it to (as I recall) f/11 max, and there are stops of "1", "2", "3" and "4", corresponding to 11, 16, 22, 32 (or am I one stop too big throughout? Haven't even looked at it for awhile). The disk unscrews easily and the lens becomes an f/5.6. It's easy to cut little triangular pieces of tape for markers. And yes, the rapid rec trick is great. I think I discovered that in the first of second year of my career (must have been 1964 or so). Beautiful, if you like that kind of image.

An old friend who shall go unnamed (one of the current breed of old masters) laughs at me for spending so much money at Edmund Sci. He goes to the drugstore and buys a pair of cheap reading glasses, and gets two cameras for $3, or one stereo. But then, he doesn't get achromats for that price. (He also thinks pinholes are "too damn sharp").

Another weird lens I have of this type is the rear element from a Pentax 135mm I got broken at Goodwill. The defects are of excellent quality.

I don't do a lot of this anymore, but it is a nice addition to the large format pinhole stuff, zone plate, etc.

[Mark Sawyer]

A recent thread on using another cemented doublet:

http://www.largeformatphotography.in...ight=%2430

These things are everywhere, just waiting for someone to let their magic out. They can sometimes sing...

[Chauncey Walden]

Having just seen Mark's prints with this lens in person at Foto3, I can say that they are really beautiful images. Way to go Mark!