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View Full Version : Plasmat vs Tessar vs Dialyte



Richard K.
25-Mar-2011, 07:30
OK,I've been *curious about this for a while...

What is the advantage of using say a Sironar 480 mm f/8.4 vs a 19" f/11 Red Dot Artar vs a 450 mm Nikkor f/9 other than the slightly faster maximum aperture (ignoring the slight difference in focal lengths)?

Could you please tell me, specifically, by comparing, the performance attributes each design has in terms of coverage, sharpness across the field and evenness of illumination...maybe relate in terms of covering 11x14...

*to put it in a more pragmatic way, why spend more money and take on more weight with the Sironar compared to the Nikkor when the Nikkor is just about as bright and only 1/3 the weight? What, if any, disadvantage is there to the Nikkor?

Thanks all!!

Arne Croell
25-Mar-2011, 07:54
Coverage is larger for the Plasmat - so for your example (480mm), if 8x10 is the largest film format you use and you're not doing skyscrapers, the other two will have enough coverage. Typically, a dialyte is about 42-48, a Tessar around 55, and a Plasmat around 70.

Richard K.
25-Mar-2011, 08:15
Thanks Arne. So it's to do strictly with coverage? But the Nikkor has a rep for extended coverage. I guess it's really just a large circle of illumination rather than definition (and probably more than OK for contact printing)? What about central and edge sharpness (on 8x10) for the 3 mentioned lenses?

E. von Hoegh
25-Mar-2011, 08:21
The Artar may be set up for close ratio work. Supposedly, the ones factory mounted in shutter were optimised for general use, and the barrel versions for copy cameras ( close ratio).

But a barrel Artar does a damn good job at infinity.

Check that the Nikkor coverage is not specified at 1:1.

Arne Croell
25-Mar-2011, 08:25
Thanks Arne. So it's to do strictly with coverage? But the Nikkor has a rep for extended coverage. I guess it's really just a large circle of illumination rather than definition (and probably more than OK for contact printing)? What about central and edge sharpness (on 8x10) for the 3 mentioned lenses?
Richard, both Tessars and Dialytes have much larger circles of illumination than of sharp coverage. Of course you can use that if there is no defined feature in the corners (sky), or by stopping down a lot you can extend the official coverage, especially if contact prints are the final result. Of the three lenses I only know the 450mm Nikkor, but since 8x10 is my largest format, I have not used it beyond its official image circle.

Arne

cdholden
25-Mar-2011, 08:26
I can't quote specs, but the Sironar was designed to be a photographic lens, where the other two are process lenses. As Arne pointed out, that version of the Nikkor will have more coverage than the Artar.
Any of the 3 will work fine for 8x10. As the format gets larger, those comparisons will change as they approach their design limitations.

Chris

Richard K.
25-Mar-2011, 08:41
Thanks Chris and Arne. Hey Chris, was that you that commented on my book on ebay? :)

Mark Sawyer
25-Mar-2011, 10:38
The Nikon 450-M is a lf camera lens, not a process lens. (There is a 480mm Apo-Nikkor that is a process lens.)

Tessars are one of the most versatile designs to modify for whatever purposes. Besides the standard Tessar, there are macro-Tessars, micro-Tessars, aerial Tessars, wide-angle-Tessars, tele-Tessars, enlarging Tessars, BioTessars, process apo-Tessars, soft focus Tessars...

cdholden
25-Mar-2011, 13:04
Mark,
Is this M lens not the same design as the older Q? I was under the impression it is. The Q's were marketed as process lenses. I don't have any cut away drawings for reference (wish I did!). I'm going from memory.

Richard,
Yes, that was me. Now I know who you are!

Chris

Gem Singer
25-Mar-2011, 13:24
The Nikon/Nikkor f8 450M is a four element lens.

Nikon made 200M, 300M, and 450M Tessar lenses .

I have owned all three of them. Still own the 300M.

Even though they have smallish maximum apertures, they have large enough image circles to enable bright focusing on the ground glass.

Dan Fromm
25-Mar-2011, 14:28
The Nikon 450-M is a lf camera lens, not a process lens. (There is a 480mm Apo-Nikkor that is a process lens.)

Tessars are one of the most versatile designs to modify for whatever purposes. Besides the standard Tessar, there are macro-Tessars, micro-Tessars, aerial Tessars, wide-angle-Tessars, tele-Tessars, enlarging Tessars, BioTessars, process apo-Tessars, soft focus Tessars...

Mark, look before you leap. There's a 450/9 tessar type Apo-Nikkor. Also a 480/9 dialyte type Apo-Nikkor.

Look before you leap. CZJ made two (2) f/8 wide angle Tessars, Nikon made one slightly wide angle tessar type, and as far as I know that's it. Please surprise me with news of other wide angle tessars. Tele-tessar is a trade name, lenses bearing it aren't tessar types. Biotessar is another design entirely, not at all a tessar type. Again, surprise me with counterexamples.

Richard K.
25-Mar-2011, 15:02
Richard,
Yes, that was me. Now I know who you are!

Chris

Uh oh...

Do you collect first edition mysteries or were you just curious about a guy selling lenses also selling a book...? :)

Mark Sawyer
25-Mar-2011, 17:17
Mark, look before you leap. There's a 450/9 tessar type Apo-Nikkor. Also a 480/9 dialyte type Apo-Nikkor.

Look before you leap. CZJ made two (2) f/8 wide angle Tessars, Nikon made one slightly wide angle tessar type, and as far as I know that's it. Please surprise me with news of other wide angle tessars. Tele-tessar is a trade name, lenses bearing it aren't tessar types. Biotessar is another design entirely, not at all a tessar type. Again, surprise me with counterexamples.

Hi, Dan! The 450mm Apo-Nikkor process lens is a different lens than the 450mm M-series Nikkor, which was an infinity-corrected lens made specifically for large format photography and came from the factory in a Copal shutter, (the Apo-Nikkor was a barrel lens).

My understanding of the Biotessars is that there were three designs, and two were directly derived from the Tessar formula; one had the rear cemented doublet modified to a cemented triplet and the front single element modified to a cemented doublet. The other was a Tessar with an added positive element in the middle to shorten the focal length/increase the f/stop.

The Zeiss Tele-Tessar (top) seems quite related to the regular Tessar (bottom), with the front element split into a cemented doublet:

http://i55.photobucket.com/albums/g139/Owen21k/tele-tessar485schemat.jpg
http://i55.photobucket.com/albums/g139/Owen21k/Rollei35tessarcopia.jpg

Other wide-angle tessars: Exacta's 5.5cm f/8 wide-angle Tessar, Minox's Minoxar 35mm f/2.8, the Schneider Xenagon was a wide angle tessar...

Paul Fitzgerald
25-Mar-2011, 21:39
"The Zeiss Tele-Tessar (top) seems quite related to the regular Tessar (bottom), "

Damn, looks like Voigtlaender Onyx from here. :D

Dan Fromm
26-Mar-2011, 05:26
Mark, you're defending a very bad position badly. If the layout isn't () )( | )() where | is the diaphragm it isn't a tessar. "Derived from" are weasel words.

Dan Fromm
26-Mar-2011, 05:47
Mark, "derived from" is a weasel word. If it isn't () )( | )() where | represents the diaphragm it isn't a tessar. More broadly, two singlets in front of the diaphragm, the second one biconcave, and a cemented pair behind it.

I wrote that Zeiss had made two f/8 wide angle Tessars. You got the 55/8 part right, it is for the pre-WWII Exakta 66. You missed the 28/8 for the Contax RF.

Xenagon is a Schneider trade name. 35/2.8 is 7 elements in 5 groups, is recommended for 24x36. 30/3.5 is 4 elements in 3 groups, is recommended for 23.5 x 23.5; that format's diagonal is 33.2 mm; not very wide as wide angles go.

I wasn't aware of the Minoxar. I'll give you one (1) surprise. Look before you leap.

Oren Grad
26-Mar-2011, 10:04
Other wide-angle tessars: Exacta's 5.5cm f/8 wide-angle Tessar, Minox's Minoxar 35mm f/2.8, the Schneider Xenagon was a wide angle tessar...

...and the 35/2.8 Zeiss Tessar in the Kyocera/Yashica T3. I used to have one - quite a good lens for an auto-everything P&S.

Mark Sawyer
26-Mar-2011, 11:06
Zeiss also made the wide-angle Pro Tessar 35mm f/4 for use on the Zeiss Ikon Contaflex Super B cameras...

There are probably more, but my original point was that the Tessar design is perhaps the most versatile in terms of fitting almost every specialized need. Even one successful example proves the point. I can only think of two portrait (adjustable diffusion) versions of the Tessar, but they're much appreciated.

And my apologies for my weaselosity! But Zeiss (where Paul Rudolph invented the Tessar) thought the Tele-Tessar to be closely related enough to share the name.

Oren Grad
26-Mar-2011, 11:52
But Zeiss (where Paul Rudolph invented the Tessar) thought the Tele-Tessar to be closely related enough to share the name.

You can't win. From the just-posted Zeiss white paper on Tessars:

>> The Tele-Tessar is a true tele lens comprised of a positive front group and a negative rear element, i.e. a system whose length is clearly shorter than the focal length, which makes long focal lengths more convenient. There is no similarity to the general design of the Tessar and is simply intended to utilize the popularity of the name. <<

:eek: :)

Mark Sawyer
26-Mar-2011, 14:59
Hi, Oren! Mind you, from page 6 of the same white paper:

http://i55.photobucket.com/albums/g139/Owen21k/tele.jpg

and on page 8, a chart that illustrates, (bold emphasis mine): "Performance data (modulation transmission for 10, 20 und 40 Lp/mm) of a modern Tessar design, Tele Tessar 4/85 ZM for 35 mm rangefinder cameras."

Dan Fromm
26-Mar-2011, 15:36
Mark, do you know what a ProTessar is? Or, rather, what ProTessars are?

I understand them to be attachments for several versions of the Contaflex SLR. This gem is a leaf shutter SLR with, if I'm not mistaken, a fixed 45/2.8 Tessar. The ProTessars replaced the Tessar's front cell to change the angles of view. The Tessar alone saw 47 degrees. With the 35/3.2 attached it saw 63 degrees. With the 85/3.2, 29 degrees. And with the 115/4, 21 degrees. There was also a 30/8 ProTessar for 1:1.

A tessar second singlet and rear group with a bunch of other elements in front isn't a Tessar.

Please learn the difference between trade names and design types. The connection between the two is often very loose.

Oren Grad
26-Mar-2011, 16:04
Hi, Oren! Mind you, from page 6 of the same white paper:

Dr. Nasse, overheard reciting poetry in the shower:

Do I contradict myself?
Very well then I contradict myself,
(I am large, I contain multitudes.)

engl
26-Mar-2011, 17:46
If it isn't () )( | )() where | represents the diaphragm it isn't a tessar.

Agreed.

The other lenses (Tele-Tessar, Pro-Tessar etc.) being called "Tessars" is just marketing speak. They are not any more Tessars than the lens on my cellphone is a "Schneider-Kreuznach". Actually, the kit zoom of my Samsung DSLR also says "Schneider-Kreuznach", despite being a rebadged Pentax kit lens.

Some lenses might be "derived from" the Tessar, but really, a lot of optical designs are related. "Unar" means "Unar", not including the Tessar that was "derived from" it.

Jim Graves
26-Mar-2011, 21:20
If Zeiss says it's a Tessar ... it's a Tessar ... afterall, they owned the name ... and, don't forget the Bio-Tessar.

Mark Sawyer
26-Mar-2011, 23:11
Mark, do you know what a ProTessar is? Or, rather, what ProTessars are?

I understand them to be attachments for several versions of the Contaflex SLR. This gem is a leaf shutter SLR with, if I'm not mistaken, a fixed 45/2.8 Tessar. The ProTessars replaced the Tessar's front cell to change the angles of view. The Tessar alone saw 47 degrees. With the 35/3.2 attached it saw 63 degrees. With the 85/3.2, 29 degrees. And with the 115/4, 21 degrees. There was also a 30/8 ProTessar for 1:1.

A tessar second singlet and rear group with a bunch of other elements in front isn't a Tessar.

Please learn the difference between trade names and design types. The connection between the two is often very loose.

My mistake, I knew somewhere in the back of my mind that the Pro-Tessars were alternative front elements, but I spaced it at the time. :o Oh well...

And I'll allow that turning the tessar's front singlet plano-convex into a cemented doublet plano-convex (the only difference between the Tessar and Tele-Tessar illustrated) makes it a completely different and unrelated design. Everybody happy? :)

Lynn Jones
31-Mar-2011, 09:15
The important facts include: Dialyte from Goerz as Celor, Dogmar, and Artar, the latter being an apochromat, Kodak made the f 7.7 203 Ektar, Schneider and Rodenstock among others also made them as highly corrected lenses. These cover from 35 to 45 degrees and were first seen in 1899.

Paul Rudolph created the Tessar in 1902 at about f6.3, later f4.5, still later f 2.8. The coverage typically was 56 degrees although Kodak's 127mm for press cameras covered a bit more. Some years ago I tried to find out how many different tessars were created and I quit after uncovering over 95 of them.

Paul Rudolph (as an independent designer) created the Plasmat for Meyer-Gorlitz in 1918. In those days it was called a "plastic" lens type, meaning it was somewhat soft focus, as optical glasses got better the lens got better and now it is the primary wide field lens for LF, usually covering from 70 to 75 degrees, occasionally more or less.

All three of these lens types at their best are incredible, but each with its own set of negative and positive characteristics.

Lynn