Pushing a Tessar design past f/3.5 ...

[daniel_iggers]

Someone mentioned recently in this forum, in connection with a

question that I posted about Voigtlander Color-Skopar lenses, a

Tessar design, that f/3.5 is optimal for the Tessar design, and

f/2.8 versions are less sharp because they require "pushing" the

Tessar beyond the optimal point. I think most Tessar design lenses

from the early 1950s first came as f/3.5s - whether they were

Solinars, Xenars or Tessars.

 

Is it fair to assume that manufacturers sacrificed sharpness

for "speed" when moving to the faster f/2.8 designs?

 

Also: were there technological advances in lens manufacturing that

contributed to the replacement of f/3.5 designs with faster f/2.8

lenses?

[dan_fromm1]

f/3.5 optimal? That depends on what you mean by optimal.

 

The first Zeiss Tessars were f/6.3. Here's what the Vade Mecum says about them: "This was a most favoured lens and the one still used by connoiseurs! It covers 70° and is sharp and contrasty." Note the coverage. And about the original f/2.8 of 1931: "f2.8 50, 60, 75, 80mm This was designed by Merte. It is fairly common and usually really good but the original 80mm version for the 6x6cm Super Ikonta seems to be somehow different and is less liked by users."

 

You have to remember that the Tessar design underwent continuous refinement, i.e., was periodically recalculated and was further redesigned as newer glasses became available. Again, from the Vade Mecum "Morian (loc. cit.) gives the glass used in two Tessar designs, nominally of 100mm each, and says the 'old' f3.5 was surpassed in both aperture and performance by the 'later' f2.8 version and shows curves for spherical correction and field flatness."

 

Incidentally, Zeiss made Tessars, mainly for cine cameras, as fast as f/2.

 

Zeiss wasn't the only manufacturer of Tessar-type lenses. After the bad old days when Tessars were made under license from Zeiss, each manufacturer did its own design work.

 

So generalizations like the one you quoted are dangerous. Ask the lens in question how it does. Don't ask authorities, especially authorities of unknown, um, weight, how lenses of that type do.

 

Cheers,

 

Dan

[tito sobrinho]

I have a Super Ikonta B from 1937 that has a lightly coated Tessar 80mm f2.8 that takes excellent pictures as well as my uncoated 1924 Tessar 120mm f2.7 mounted on a compound #3 shutter. Excellent contrast and sharpness for both. The f4.5, f3.8 were widely used on the Rollei from 1929 until they settled on the f3.5 for the Standard in 1934 up to the Rollei T of late 70s. Leica used the 3.5 Elmax on the first Leicas but later decided on the 3.5 Elmar design. My Elmar 2.8 for my Ms is a marvellous lens. I think it is more due to camera design than anything else.

 

But of course, I don't "shoot" with any of my Tessars and or modified clones in the wide open mode.

[mike_elek]

I have an old uncoated f/2.8 Tessar for a Contax. I'll shoot a roll wide open and get back here with the results. Just for fun, of course.

 

Also, Zeiss-Ikon used the f/2.8 Tessar on several of its postwar 35mm cameras, including the folding and rigid Contessa, folding Contina, as well as being the "premier" lens for its medium-format B cameras (6x6).

 

I'm sure that lenses were reformulated and recalculated, and lens coatings probably helped as well.

[Troll]

I've always thought it interesting that while pre-war Tessars for the Contax were f:2.8, the post-war model was only f:3.5.

[tito sobrinho]

Indeed, as I have a Contax I with an uncoated collapsible Tessar 5cm f2.8.

[winfried_buechsenschuetz1]

'I have a Super Ikonta B from 1937 that has a lightly coated Tessar 80mm f2.8'

 

I don't think that this lens actually was coated, since lens coating was invented just around that year, and very probably was not used on consumer optics very soon. I have a Zeiss Novar lens dated 1931 which also has a sligthly blueish shine, but I think this is rather due to glass corrosion. In an old manual about optics it was mentioned that on some types of optical glass can be corroded 'on purpose' to create effects similar to coating.

 

However, as mentioned by others, the Tessar lens was re-designed several times. I only know the post-war Tessar lenses from the east german Zeiss plant (they redesigned it around 1953), and these give excellent results at f/2.8 80mm (for 6x6) and f/2.8 50mm (for 35mm).

 

Also, I recently compared a pre-war Schneider Xenar against a pre-war Zeiss Novar (triplet) lens, and the Xenar hardly was superior to the Novar. The Xenar was rated at f/3.5 75mm but was everything but sharp from edge to edge when fully open. At f/4 it had similar performance as the Novar (rated 4.5 75mm) fully open.

 

I think in past decades some manufacturers actually traded lens power for sharpness. There are quite a few mediocre (even german) lenses rated at f/2.8 or even f/2 but the full aperture of some of them is hardly usable and is rather a figure for the advertisement.

[tito sobrinho]

I have a Super Ikonta C 1934 with a Tessar 105 f4.5, Contax I Tessar 50mm f2.8, 3 Rolleis Standard with Tessar f3.5, f3.8, and f4.5, Tessar 120mm f2.7, Rolleicord Art Deco Triotar 4.5, as well as 3 Dagors, Zeiss Protar series VII, Wollensak Velostigmat wide angle Series III for 8x10 all uncoated and none show me the bluish tint that I have on my Super Ikonta B 80mm Tessar 2.8. What follows is a excerpt from Rudolph Kingslake's book.

 

"In 1904 Taylor patented the use of acids or other chemicals to cause tarnish deliberately on the surface of a lens, to reduce reflectivity. However, this process proved to be uncertain in operation. The whole subjet was opened up in 1936 when A. Smakula of Zeiss invented the process of coating lens susfaces in a vacuum with a thin evaporated layer of low index material".

[tito sobrinho]

Oh, I forgot! My uncoated 1934 Rollleicord model I (Art Deco black version) with a 75mm triotar f3.8 as well as a 1936 Rolleicord Ia Triotar 75mm f4.5, and a 1936 Rolleicord model II Triotar 75mm f3.5. Again, none of the above show the bluish tint found on my 1937 80mm 2.8 Tessar. Perhaps, in 1937 Zeiss coated the more expensive lenses to be used on their Zeiss products.

[richard_oleson]

Certainly they traded sharpness for speed, and they still do, although they're better at it now, with computer design and a much broader range of glasses to choose from. The Tessar got noticeably better with a redesign around 1960, and I think whether it was a fully capable f/2.8 performer before that depends on your standards and perhaps the specific lens you're looking at. The 80/2.8 that appeared on the Exakta 66 in 1954 and the Praktisix soon after was generally agreed to be inadequate for exacting medium format use, and was replaced quickly by the Planar-like 80/2.8 Biometar (i have this same 80/2.8 tessar in M42 mount for 35mm and it's not very impressive).... but the 45 and 50mm f/2.8 tessars on contaflexes were seldom criticized for their performance....

 

:)=

[MTC Photography]

My Zeiss Ikon Contaflex has a 50mm f/2.8 Tessar, same with my rigid

Contessa. Minox 35ML Minoctar 35mm/2.8 and Minox GT-E Minoxar 35mm/2.8 are all Tessar type design. <p>

Edixa 16M has 25mm f/2.8 Schneider Xenar lens; Xenar is also

a Tessar type design.

[tito sobrinho]

Hmm! The same thing happened with the Rolleiflex A 80/2.8 from 1950. They used the Jena Tessar 80/2.8 in a hurry in order to compete with the newer 1948 Hasselblad 80/2.8 Kodak Ektar. The Tessar Jena, were made during the end of the war with no QC; it was a bad lens but, in 1952, Rollei went to the Biometar 80/2.8 giving birth to the Rolleiflex B.

[davecollopy]

I always felt the tradeoff was sharpness for contrast. The tessars I�ve used, 4.5 and 6.3 from the �20�s, are noticeably sharper than the postwar 80mm 2.8 on my Ikonta or even the 3.5 75mm, but the difference in contrast is what is really profound. The sharpness of the 80mm 2.8 is still acceptable for a folder. I attribute the sharpness of my 6.3 tessar, the sharpest tessar I�ve owned, more to over-engineering that was common to manufacturing of the period as this particular lens was used almost exclusively for contact prints.

[winfried_buechsenschuetz1]

Posted this earlier in the wrong thread...

 

I have severe doubts that a) coated lenses reached the market just two years after patenting this process and b) that Tessar lenses were coated pre-war. The only coated Zeiss pre-war lenses I have heard of are the f/1.5 50mm Sonnar lenses. See

 

http://www.cameraquest.com/zconrf2.htm

 

 

Also, your camera might be a third-party mix-up. In a german camera collectors magazine someone published a photo of a Voigtlaender cameraa equipped with a Tessar with a turning prism assembly (which is useless on a Voigtlaender camera), obviously coming from a 6x6 Ikonta rangefinder.

[tito sobrinho]

My camera in E++ condition #C5251 has a lens# 2170342 mounted on a black rim Compur Rapid. Maybe, the camera was sent back to Zeiss in the 50s in order to coat the lens. As I said, it takes excellent pictures. I think, people are confusing this lens made before the war to the ones poorly manufactured in a hurry to satisfy Herr Heidecke for his Rolleiflex 2.8A in order to compete with the 1600 Hasselblad 80/2.8 Ektar.

 

BTW, my Rolleiflex 2.8 collection is missing the A (Jena) as well as the rare and difficult to find Rolleiflex B (Biometar). I have the A type 2 with the 2.8 Opton Tessar. The rest all in Ex++ to mint condition C,D, E, and F were relatively easy to find.

[winfried_buechsenschuetz1]

Yes, this serial number is from 1937. I don't know whether Zeiss also offered a 're-coating' service, Leitz did so for many of their lenses still in the 50s, so there are a few Leitz lenses on the market dating from pre-war but having a post-war coating.

[richard_oleson]

Many people in the early 1950s offered recoating service. I once had a set of prewar Contax lenses, a 35 Biogon and a 135 Sonnar, both beautifully coated.... I'm sure not by Zeiss...

 

:)=

[mike_elek]

I bought a Contax f/2.0 5cm prewar Sonnar that appears to have been coated at some point.<P>

 

It's one of the older Sonnars for the Contax I. It has the black band around the barrel. You can see it on the "lens" page of my <a href=http://host.fptoday.com/melek/zeiss/contax_iia.html><b>Contax IIa minisite.</b></a><P>

 

You can see the blue reflection of the coating of the lens, which is in the lower right corner of the photo. It was very nicely done, but by whom?<P>

 

However, because I was laid off, was forced to make two major moves (from Hong Kong to New Jersey to Pittsburgh), had to sell my house and buy another house (and close Dec. 19), I haven't had much time to enjoy photography this year. So I can't tell you how it performs.<P>

 

But while I'm testing the Tessar, maybe I'll shoot half the roll with this Sonnar!<P>

[jeroen dommisse]

I believe the Olympus Epic/Stylus/Mju lenses are Tessar designs too.

[tito sobrinho]

Mike, what a wonderful site. I browsed through the photo gallery and I still think that the Zeiss Ikon Sonnar 1.5 was much, much better than the contemporary Leitz Summarit 1.5 (Schneider Xenon clone?).

[MTC Photography]

The performance of 50/2.8 Tessar can be better than 50mm/3.5 Tessar.

For example, looking at the ray intercept plot of Tessar USP2724992 f2.8 Tessar, its performance is better than TESSAR USP2084714 F3.5

lens; the former has less 34d order and 5th order abberations<p>The key difference is that the f2.8 used higher index glasses, three of the four glasses have n

>1.60, one of the positive element of cemented doublet used high

refraction index lanthanium glass, n=1.717, while the f3.5 tessar

used two glasses with n<1.58

[chuck_foreman1]

Wow Martin you really know your glass!! Knock my socks off!!