More on classic lenses

Most is from Richard Knoppow for the Large Format Page

Contents:


Shutters

A table of older aperture systems

The Compound is an old type shutter using an air-brake to control the speeds. When clean they are quite reliable and have the advantage over the older Ilex shutters of having a time setting independant of the speed setting so that you can focus without resetting the exposure time. They are also quite easily modified to provide for X-synch for strobe flash.

The old Ilex shutters are often found on older commercial lenses. If really clean they are acceptable shutters but should be exercised a couple of times before making exposures. They were intended to run without any lubrication. When they are lubricated they tend to be erratic. The cure is a carful cleaning.

Ektars

Ektar was used by Kodak as a trade name for its premium lenses. There were a number of generic designs used for them. Ektars were all very high quality lenses. The ones made for press and view cameras were mostly Tessar types. Exceptions are the Wide Field Ektars, which are four element air-spaced lenses of the "Double Gause" type, and the 203mm f/7.7 Ektar which is a four-element air-spaced Dialye type, made slightly non-symetrical to improve its correction for distant objects.

All of these lenses are completely corrected for lateral color and were intended for color photography. Some Ektars were coated as early as 1940. These include the series of f/6.3 lenses marked "Eastman Ektar", which are the predicessors of the Commerical Ektar series. The early coatings were soft and applied only to inside surfaces.

Other early coated Ektars were the lenses made for the Ektra camera and for the Medallist. Other Ektar lenses were not coated until after about 1946.

Kodak had a very advanced glass plant and made their own optical glass. They developed commercially the rare-earth glasses discovered at the National Bureau of Standards and were one of the first manufacturers to use Lanthanum Crown glass.

Ektars are also among the earliest lenses to be cemented with thermo-setting synthetic adhesives rather than the traditional Canada Balsam.

Generally, an Ektar in good condition will have excellent performance even by current standards. Kodak quality control after about 1938, when Rudolph Kingslake took over the optical department, was excellent.

Kodak lenses from about this date on can be dated by the two letters preceding the serial number. They are a code for the last two digits of the years of manufacture. The code word is C A M E R O S I T Y standing for 1,2,3,4,etc. e.g. a lens marked ES-413 was built in 1947.

The Commerical Ektar was a series of f/6.3 Tessar type lenses intended for use on view cameras. Tessars have somewhat better performance at f/6.3 than when faster.

_All_ lenses sold under the Ektar name were highly corrected for color, especially for lateral color, which is sometimes known as chromatic magnification. In other words, the size of the images from different colors are the same size.

The Commerical Ektar series was sold as Eastman Ektars prior to about 1946. The earlier version was soft coated on insided surfaces, the Commercial Ektar is hard coated on all surfaces and bears the "circle-L" mark for coating standing for Kodak's trade-mark "Luminized".

Not all Ektars are coated. Most of the f/4.5 series, for use on press cameras, etc., were not coated until after about 1946 (I don't know the exact date Kodak started coating all its lenses).

Most Ektars for medium and large format are Tessar types, but Ektar was used as a trade-mark for a quality level rather than a specific design. For example, the f/1.9 lens for the Ektra and the Aero-Ektar are both seven element Biotar types, the 45mm f/2 lens for the Bantam Special is a six element Biotar. At least four other prototipical designs were used for Ektar lenses.

Undoubtedly, the quality of the coatings varied over the fifteen or so year period that Kodak continued to make lenses after coating was adopted. Unfortunately, according to my contact at Kodak, the historical material which would clarify this sort of issue has been buried away somewhere and is not accessible.

My statement about the coating of Eastman Ektars is based on statements made in a 1940 or 1941 Kodak lens handbook. This states that this series and the also the lenses for the Ektra camera were soft coated.

Some specific Ektars

By Michael Liczbanski

The quality varies depending on the vintage & purpose of Ektars...
I realize that the original post was most likely about the LF Ektars, but
many MF Ektars are on the market as well (sometimes sans their original
cameras so one cannot tell without testing whether or not they cover
4x5...)  Here is a brief description of just a few Ektars:

Kodak Ektar 2/45 (for Bantam Special)
6 elements in 4 groups, covers 28x40mm negatives

Kodak Ektar 3.5/100 (for Kodak Medalist)
5 elements in 3 groups, covers 2 1/4 x 3  1/4  (and 6.5x9 cm)

Kodak Ektar 3.7/105
4 elements in 3 groups, covers 2 1/4 x 3  1/4
*** A very good lens, also used on the Precision enlarger.  Sharp and
contrasty.

Kodak Ektar 4.5/101 and 4.7/127
4 elements in 3 groups, covers  2 1/4 x 3  1/4  and 3 1/4 x 4  1/4
respectively
*** Also a great lens, esp. for 6x9

Eastman Ektar 6.3/8 1/2in; 6.3/10in; 6.3/12in; 6.3/14in
4 elements in 3 groups, these lenses cover 5x7 to 8x10in.  The 14 inch
covers also 11x14 at f/16 and below, but without much room for movements.
*** Great, fully corrected lenses (coated!)  Expensive, big and still very
useful
even today.  All have a great circle of coverage and a very "sweet", "full
bodied" shadow detail.  The minimum f stop is f/45, whereas I'd prefer f/64
or even smaller for 8x10.

Kodak Ektar 1.9/50; 3.5/50; 3.3/35; 3.5/90; 3.8/105; 4.5/135 (for Kodak
Ektra)
All cover (some barely) 24x36mm.
Come in a variety of designs (even a nice triplet at 3.5/90) and their
quality varies from lousy (1.9/50 esp. wide open) to superb 3.5/50, 3.3/35.

Well, the Anastigmat was a separate line of lenses  - essentially Tessars
with the exception of the 6.3/105, 6.3/130 and 7.7/8in.
Some notable Anastigmats were:
7.7/8in
Covers 5x7 "process" lens, well-corrected for close-up work.  Quite nice

5 1/2in, 6 3/8in, 7 1/2in, 8 1/2in, 10in and 12in - all f/4.5
Cover from 3 1/4 x 4 /1/4 to 8x10 (with movements) depending on the focal
length.  Fine lenses (great for architecture, as they don't display much
linear distortions of any kind.)

There were also Anastigmats for small format cameras (35mm, Bantams and
Vigilants)

Well after WWII, Kodak started tinkering with their lenses a lot, and the
distinctions between many lens lines blur in the 50s.  (The summary above
describes the mid-to-late 40s status quo.)

 An additional note.  Many prewar Kodak lenses were sold as Kodak
Anastigmat followed by a number. It would seem from catalogue data
that numbers in the "thirty" series, like K.A. No.33 are Tessars,
those begining with 70 seem to be dialytes (four element air spaced
type).

Here are the numbers (actually in the Kodak catalogue, the numbers
precede the lens name:)  All data come from Kodak Reference Handbook, 1946
(practically unchaged from 1940-1946.)

No. 31 Kodak Anastigmat f/4.5  5 1/2in (140mm)
No. 32 Kodak Anastigmat f/4.5  6 3/8in (161mm)
No. 33 Kodak Anastigmat f/4.5  7 1/2in (190mm)
No. 34 Kodak Anastigmat f/4.5  8 1/2in (216mm)
No. 35 Kodak Anastigmat f/4.5  10in (254mm)
No. 36 Kodak Anastigmat f/4.5  12in (304mm)

All appear to be Tessars (4 elements in 3 groups, 4 internal air surfaces)

No. 70 Kodak Anastigmat f/7.7 8in (203mm)

(Symmetrical, air-spaced, 4 elements in 4 groups, 6 internal air surfaces.)
BTW, that's the one I like on a 4x5 VC the best (it will cover 5x7, but with
4x5 you'll sooner run out of swings and titlts, than go beyond its circle of
coverage.)

Goertz (Red Dot) Artar

Unless the remounting was butched it should be an excellent lens. Kingslake gives some history of the Artar in his book _A History of the Photographic lens_ The Apochromatic Artar was designed by Walter Zschokke of Goerz in 1904, it became the most widely used process lens for decades. It is a true apochromat and very well corrected for other aberrations as well. The corrections of "dialyte" lenses like the Artar do not change much with distance. While it is optimized for 1:1 (the later "Red Dot" series was not) it will perform very well at infinity. The lens begins to get a little coma in the corners but stopping down a bit will cure this. Optimim performance is around f/22. A 12" Artar will just barely cover 8x10 at infinity, coverage angle is usually given as 47deg for this type, but my 12" Artar which is older than yours does just fine and is one of the sharpest lenses I've ever used. There is just no margin for movements. .

They are famous lenses. The C.P.Goerz-American Optical Co. was originally the U.S. division of the German Goerz company which was important before the first world war. After the war the German parent was restricted in what it could make (by the German government) and in about 1926 was absorbed into the Zeiss-Ikon combine. The American division became an independant company and continued to manufacture the Goerz line. Goerz was the manufacturer of the famous Dagor lens. The designer of the Dagor, Emile von Hoegh, brought a second lens design to Goerz, a four element air-spaced type sometimes called a "dialyte". This became the basis for several Goerz lenses including the Artar. The Artar was designed by W. Zschokke and F.Urban in the late teens. It is an apochromatic lens originally intended for three-color graphic arts use. Goerz continued to make Dagors and Artars in the US gradually refining the designs. The Red Dot series of Artars came out in the early 1950's. They are an improved version of the older Artar and are coated. These lenses, although intended for close work, do very well at infinity. They are extremely sharp and generally have excellent performance. The original Artars were adjusted for best performance at 1:1 but the Red Dot series were adjusted for better performance at a distance and the image/object ratios vatied from about 10:1 to 1:1 depending on focal length and when it was made. Artar's cover a rather narrower field than a Tessar and your 9.5 should cover a 5x7. The field does not increase when the lens is stopped down. Optimum f: stop is f:22 This is a super lens.

Red Dots are apochromatic, they are also coated. The Artar was the most widely used process lens for decades. They were also widely used for color advertising work. Red Dot Artars in shutters are optimised for medium distance rather than 1:1 and should be just fine at infinity. I have a 19" Red Dot in a barrel and an old 12" Apo Artar in a dial set Compur. They are both extremely sharp lenses. Artars in shutters are rather more expensive than in barrels. My 19" in barrel cost $225 but that was a rather low price for it.

Coverage is limited to about 47 degrees at f/22. This works out to an image circle of 210mm for your 9.5" lens. This will just cover 5x7 with no movements so it will allow moderate though not extreme movements on 4x5. Unlike most modern lenses, the illuminated circle is larger than the sharp image circle, so you need to take some care that you don't exceed the coverage of the lens accidentally. John Sparks.

On Goerz Serial numbers and dates


Goerz Amer. Optical Co. Serial #'s from 
Eddie Bolsetzian (former Goerz Tech.)

Lens #

70001-140935     1902-1903
150000-190170    1903-1905
200941-224267    1906-1908
223775-226630    1908-1909
310001-315734    1911-1914
315735-320000    1914-1918
751240-756909    1927-1937
755300                1934
756910-765730    1937-1945
765730-771199    1945-1948
771200-780169    1948-1954
791500                ~1955
ser iii 61/2 #222788    1910
ser iii 81/4  #222836   1907
14" Dagor #190994       1905
19" dagor #757427       1938
ser iii 480mm #174429   1904
Artar 19" #396635       1922
artar 30" #751030       1926
first red dot artar #779612  oct 1953

These are the dates passed to me, I make no claims about their accuracy. Michael Buchmeier

On Dagor History

I have Goerz American Optical Co.catalogue copies from 1913,1938,1955,1963,1968, and 1971 all of which list dagor lenses. The W.A.Dagor is listed first in the 1938 and golden dagor (both W.A. and standard) in 1955. in around 1964 the company changed their name to Goerz Optical Co. Inc. From the illustrations in the catalogs the golden dagor was of the "gold dot" configuration by 1963 but is still referred to in the catalog as the "GOLDEN DAGOR" right up to and including the 1971 spec. sheet. Gold Rim and Gold Dot are apparently only useful descriptive terms to describe the appearance of these lenses but may only represent an evolution in trim much like a chrome bbl vs a black bbl convertible Symmar. Goerz did not use these terms in their sales literature! Goerz was bought out first by Kollmorgen in 1971 and listed a Pittsburgh address, and was subsequently bought by Schneider in 1972(?). The 355mm Kern Dagors were produced in two lots after that, but Schneider did sell out existing Goerz inventory after the buyout, and in fact a few American made 14" gold dot lenses are around with Schneider's name on them. These are in Copal Shutters, marked in inches, and are not multicoated, but are fine lenses nevertheless. Michael Buchmeier.

Coverage of Dagor

For many years Bausch and Lomb were licensed by Zeiss to make Zeiss lenses in the US. Comparing the catalogue specs for Tessars one finds a full plate size difference between the catalogues for the same focal length and speed. i.e. a 12" f"4.5 series 1C is listed as covering an 8x10 by B&L but only 6-1/2 X 8-1/2 by Zeiss. However Zeiss gives the coverage for "small stops" as 14-1/2" circle. So Zeiss is giving plate size for good image quality with the lenses wide open and B&L for smaller stops where the corners get better. I think this explains the difference in the ratings by the two companies, Zeiss was just a little more honest about what the lenses would do. There is a difference in the circle of illumination and the circle of good defininition with most lenses, the circle of illumination being often much larger. The circle of illumination of a Dagor or similar lens is about as large with the lens wide open as it is stopped down but the sharpness of the periphery of the image isn't very good, this area gets lots sharper as you stop down. To contrast, "dialyte" lenses, like Artars and Dogmars are pretty sharp to the edges of the image wide open and the coverage (which is limited) doesn't get larger as the lens is stopped down. Triplets and Tessars are midway between these. Generally, older wide angle designs ( and the Dagor really is a wide angle lens) perform best at rather small stops. Its considered good optical design practice to vignette the illumination circle of a lens bewond the point of good performance, (see _Modern Lens Design_ by Warren Smith or Kingslake's design books), so thhis _may_ account for smaller coverage angle in some late versions of old lenses but you would have to derermine is by actual measurement. Both my Dagors are very old and both have the advertised coverage, but I have no good way to measure the quality of the image at the limit of coverage.

On Dagor performance

Here is some data from bench testing a lens, "Goerz Dagor Focus 7in. f/6.8, No. 392662." This lens was produced sometime between 1918 and 1927 (thanks, Mike Buchmeir). If this old lens is representative of others from that time, here is some advice: the spacing is critical, and also, the orientation of one cell relative to the other. (Turning one cell a full turn changes the off-axis resolution by a factor of two and back again. It seems that the optical-centering-error reputation is deserved.) This Dagor shows very little difference in focal length (perhaps .2 mm) wide open compared to the small apertures. Vignetting for 5x7 looks like about a stop's worth at f/16. If you have an old lens you would like tested, let me know (no charge, you pay postage). I'd be interested in seeing how other early lenses perform. Also, can anyone post performance data of any modern lenses-- to show us what the improvements in resolution and coverage have been? Now, here's the bench test data (considering all the caveats, not too shabby! ;-)
angle
off-axis  0    5   10   15   20   25   30   35   40  degrees

f/6.8    85   75   65   55   45   35   25    5    0  lines/mm

f/22     70   70   70   70   65   55   40   10    0  lines/mm
         ^diffraction lim^

f/64     30   30   30   30   25   25   25   20   10  lines/mm
         ^diffraction lim^
Corners of the film with this 7" lens are at:    4x5: 24 degrees
                                                 5x7: 31 degrees
                                                8x10: 42 degrees

The astigmatism correction, done well in Dagors for the first time in
history, is interesting :

(table values are the difference in mm from the on-axis focal
distance, positive away from the lens)

angle
off-axis  0    5   10   15   20   25   30   35   40  degrees

sagittal
focus     0    0  -.2  -.5  -.5    0  +.8  +3.0

tangential
focus     0    0    0  +.2  +.3  +.2  -.8  -2.5

Larry Whatley

B&L 5x7 Tessar

>Here's a surprise-- this old lens is surprisingly bad... and will
>probably make surprisingly good pictures!  (Can anyone tell me
>specifically about this "5x7 Bausch - Lomb Tessar Series 1c Pat. Feb24
>1903 No 2448486"?)
>
>It has a field about the same as a Dagor (!) because the astigmatism
>corrections are stretched out to cover more than 60 degrees, even wide
>open.  The problem is that the resolution falls to 5 or 10 lines/mm for
>about half the field for the wider apertures.  (One authority on fine
>print resolution says a resolution of 12 lpmm in the _print_ is
>considered to be truly "fine," by the way.)
>
>But... at apertures of f/22 and 32 this lens will cover its entire
>plate with resolution of 40 lines/mm or greater-- it sharpens up very
>nicely.  Perhaps this old lens was designed on purpose this way to
>cover this wide field angle, unusual for most tessars, with the fast
>aperture intended just for focusing, not taking?
I have one of these, it was on an old Agfa/Ansco view camera but is much older than the camera. Mine is S/nr. 3050646. It makes very sharp images. My guess as to date is based on the following clues: 1, It is a B&L not a B&L-Zeiss, makes it probably after the entry of the US in WW-1 (1914). 2, In 1927 the patent law was changed to require the actual patent numbers rather than just the date to written on products, makes the lens before 1927. 3, Patents are good for 17 years, 1903 + 17 = 1920. B&L may have continued to print the date on the lens rings after this. B&L was engaged in war production after 1914, they had the only credible optical glass factory in the US so got very busy. Best guess as to date therefore is 1918 to 1920. (Watch someone blow this closely reasoned argument to smithereens:-)) Mine is in a Wollensak Optimo shutter with marked speeds to 1/300 sec. This is an interesting shutter in which the shutter blades are double sided and turn through a complete 180deg when its tripped. When tripped again, they return. This permitted higher speeds than the usual oscillating blade variety but the effeciency at higher speeds wasn't too good, so the 1/300 may have been ligit for effective spped with the lens wide open when the thing was new. It makes about 1/50th now. This shutter dates from about the same period. This lens positivly amazed me when I first used it. Please note that even though its marked 5x7 the focal length is a little on the short side, about 180mm. It would be interesting to test more than one example to see if what you found is characteristic of the type or just an individual lens. It seems to me that B&L had some patents for modified Tessars themselves but I don't remember the dates. 1903 is the date of the Rudolph patent for the Tessar in the US.

Xenars and Other Tessars

The Xenars are great lenses, in the newer smaller size the will preform wonderfully on a press type camera. Older 210mm and above Xenars come in f/4.5 and get large and heavy. I have a 210 f/4.5 which is an excellent lens, but in a #3 shutter it is too heavy for a graflex and at slow speeds induces "shutter shake". All tessar type lenses should be used at f/11 or smaller. This is not really a problem since most sources suggest using any lens at two stops down from wide open (symmars f/5.6 = f/11). A real problem is cost. If the Xenars are new they cost apx. what USED Symmar/Sironar/Nikon/Fuji etc. 6 element designs cost. The older chrome Symmars are generally a good buy used (as is most non multi-coated ventage glass). Just check out the lens and shutter. However, at 300mm you are back to a #3 shutter. At 300mm the new Xenar may be the best choice for you or you may want to look at a used Apo Rronar as they come in a #1 shutter. The Ektars are generally great lenses, if ... a good shutter can be found. I am rather fond of the 203 Ektar, not a tessar type, rather an air spaced design (like artar). Some Ektars can be found in compur shutters... this is good stuff, later ventage. Ektar coatings can be soft though. Reynolds Neely

f4.5 480mm Voigtlander HELIAR

This enormous chunk of glass is one of the classic lens types. The Heliar was designed originally by Hans Harting of Voigtlander about 1900 although the version made later is a modification of the orginal with the order of the cemented elements reversed. This is a five element lens with the outer elements cemented. Kingslake classifies it as a variation of the triplet. Heliars had a reputation for being deluxe lenses with excellent performance. The coverage angle is somewhat limited compared to the simpler Tessar, usually given as 46deg. Heliars were made for probably about 70 years with design changes periodically. Unfortunately, I don't have any Voigtlander serial number infomation to help date this one. More about this lens and its designer may be found in: _A History of the Photographic Lens_ Rudolph Kingslake, 1989, San Diego, The Academic Press Inc. Still in print.

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