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View Full Version : Calumet Caltar 20" f7

Thom Bennett
17-Jun-2011, 13:27

Louis Pacilla
17-Jun-2011, 14:03
You may be able to find the info here. Scroll down until you find the Caltar lenses

http://www.cameraeccentric.com/html/info/calumet_2.html

Thom Bennett
17-Jun-2011, 14:32
Nice link! No direct reference to image circle but "it covers an angle of 56 degrees wide open and 64 degrees as the lens is stopped down." What is the method whereby one can figure out the image circle with that information?

Dan Fromm
17-Jun-2011, 14:50
In Excel. circle covered = focal length*2*TAN(RADIANS(angle in degrees/2))

Thom Bennett
17-Jun-2011, 14:58
"I was told there would be no math."

First one to name who said this and in what context wins.

Thom Bennett
17-Jun-2011, 15:01
Oh, and thanks Dan.

Kerry L. Thalmann
17-Jun-2011, 15:58
Nice link! No direct reference to image circle but "it covers an angle of 56 degrees wide open and 64 degrees as the lens is stopped down." What is the method whereby one can figure out the image circle with that information?

Although it doesn't say it in the catalog referenced, those coverage angles do not apply to the 20" f7 Caltar, they are specific to the shorter 4/3 Tessar-type Ilex-Caltar lenses. The 20" f7 Caltar is not a 4/3 Tessar-type. Several years ago when I wrote an aritcle on Caltar lenses for View Camera magazine I discussed this lens with Lynn Jones. I'll have to double check my notes, but from memory, according to Lynn the 20" f7 Caltar is a 3/3 triplet design with 35 degrees of coverage, which equates to an image circle of about 320mm - enough for 8x10 with small movements.

Kerry

Thom Bennett
17-Jun-2011, 18:30
Kerry, thank you for that info. Extremely helpful! I'll look through my back issues of VC for that article.

Kerry L. Thalmann
17-Jun-2011, 19:12
Thom,

You're welcome. The article is in the May/June 2003 issue of View Camera. My recollections above were correct (3/3, 35 degrees, 320mm IC).

Kerry

Jan Pedersen
17-Jun-2011, 20:39
In a Burke & James brochure the lens is listed with a 58 degree coverage and as a lens for the 11x14 format.
Mine which is a late version with high serial number have the exact same reflections as my 375mm f6.3 Caltar
It is possible that the lens was born as a triplet and later changed but some at least are Tessars.

Mark Sampson
17-Jun-2011, 21:13
I don't have any idea about this lens' design or coverage. But in a '70s catalog I once had, Calumet advertised it as being made to give a flatter perspective than a normal lens, when shooting 8x10 tabletop. So perhaps infinity coverage wasn't a factor.

Kerry L. Thalmann
17-Jun-2011, 21:50
In a Burke & James brochure the lens is listed with a 58 degree coverage and as a lens for the 11x14 format.
Mine which is a late version with high serial number have the exact same reflections as my 375mm f6.3 Caltar
It is possible that the lens was born as a triplet and later changed but some at least are Tessars.

Not according to Lynn Jones when I spoke with him several years ago. Lynn did indicate that the circle of illumination was larger (about 45 degrees), but only the central 35 degrees was sharp enough to be considered usable. So, just looking at the image circle on the ground glass may make it appear to cover 11x14.

I really wouldn't put too much stock into specs in the old Burke & James catalogs. They often tried to make the products they were selling appear more desirable than the actually were (like the "Berlin Dagors" they sold that were assembled from old cells that were originally rejected due to poor quality).

Kerry

PolarBear1973
18-Jun-2011, 00:09
I've used it on 8x10 for portraits. On my 16x20, it is good for photographing people, cars, and medium sized houses. It does not cover the 16x20 format to infinity. The lens does not have a hard edge at the end of its sharpness, but rather falls off gradually.

It is really nice looking at the ground glass with such a large maximum aperture. I would highly recommend this lens.