New. C Sonnar T* 1,5/50 ZM

awilder said:
The 6/4 optical layout is interesting for a 50mm Sonnar. This layout is typical of a DG design like the Planar. It indicates Zeiss chose the Sonnar designation strictly for the lens speed of F/1.5 that harkens back to their old Contax lens and has nothing to do with the optical design of a modified triplet.
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I think that's the difference between today's leica and Zeiss. Leica never stop to improve their design...........

but Zeiss, only trying to reproduce their "classic" again and again.
 
awilder said:
The 6/4 optical layout is interesting for a 50mm Sonnar. This layout is typical of a DG design like the Planar. It indicates Zeiss chose the Sonnar designation strictly for the lens speed of F/1.5 that harkens back to their old Contax lens and has nothing to do with the optical design of a modified triplet.
Click to expand...


Hmmm. The 6/4 optical design of a typical Planar or double Gauss has one single element and one cemented pair on each side of the aperture blades, with fore-aft symmetry. The new Sonnar has a cemented triplet behind the blades and 3 single elements up front. Seems kind of Sonnar-asymmetric-like to me (think of the 2nd element and 3rd element, together with the air space, as a triplet). Others probably know more about this.


David
 
awilder said:
The 6/4 optical layout is interesting for a 50mm Sonnar. This layout is typical of a DG design like the Planar. It indicates Zeiss chose the Sonnar designation strictly for the lens speed of F/1.5 that harkens back to their old Contax lens and has nothing to do with the optical design of a modified triplet.
Click to expand...

I would respectfully disagree. This is not a Planar-like design. The original f/1.5 Sonnar was a 7/3 optical layout, so yes, this new one is not an exact duplicate. So, what's the difference? A comparison of the diagrams of the current design & the original shows that the 6 elements of the new design exactly replicate the corresponding 6 elements of the original design. What's missing?

Working from the original Ernostar design, Bertele added a lower index element between the second & third high index elements to create the cemented triplet. This strong cemented interface, which elimianted the glass to air surfaces between the second & third elements was necessary to control the higher-order aberrations.

It is this cemented interface, the lower index element used to create the cemented triplet, that is missing. Why? Bertele created the Sonnar design because it was the only way available to control the aberrations otherwise inherent in this design. With the creation of lens coatings, however, such an intervention is no longer necessary to achieve the same effect.

So is it a Sonnar or an Ernostar? The question is academic because Zeiss retired the Ernostar name back in the early '30s & have since called all lenses of this design type "Sonnars" including those that have been modified via the use of modern coatings as this one has. However, a key characteristic of the f/1.5 Sonnars that distinguishes them from the Ernostars is the rear group, which is faithfully reproduced in this new lens. This 3 element group is a strong cemented interface, designed for its powerful influence on the higher order spherical aberrations in a lens this high aperture.

Zeiss calls it "a modern technological reincarnation of the classical Sonnar." With the technology of modern coatings, I say: "Fair enough." Will it have the same finger print as the old Sonnars? I have no idea, but I'm interested in comparing them. We'll have to wait & see, but I don't expect it to have the fingerprint of a Planar. The 40/2.8 Sonnar, which uses the same design principles as this one (i.e. coatings to eliminate the middle element of the triplet) has its own "look", so my guess is that this new Sonnar will too.
 
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This is interesting news, especially since I have been having Sonnar lust the last couple of weeks. I may have to get a J-3 and J-8 to practice while I save my pennies.
 
Thanks Dave, you are absolutely right. I stand corrected. I didn't see the pdf link for the lens design until I went back after reading your post. VERY interesting design with the Sonnar heritage CLEARLY evident. Similar to the old 50/1.5 but due to modern glass and T* coating, an air space can now be used between elements 2 and 3 rather than a very low index cemented lens ( 3rd element in the old design) that resulted in a cemented triplet with the old design. This may be a more intersting lens than the ZM Planar in that it will have a less clinically perfect quality to it's imaging giving it a unique signature that may be more asthetically pleasing to some people. Time and test comparisons will tell. Good move on Zeiss' part!
 
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I asked this question on the other Sonnar ZM thread below, but it appears that this is the hot place to discuss this lens... I've never used a lens with aperture blades shaped like that - will it have an effect on the OOF highlights, especially around f2.8 or 4? Any thoughts?
 
hm....not liking that .9m min focus, and also 46mm filter is sorta an oddball to find and the wide open mtf is a little all over ther place suggesting the contrast will be somewhat lower wide open but if its cheap ill keep my eye out for it instead of a 50 summicron.
 
aoresteen said:
Bad news indeed! Last year I spent a fortune having a Contax IIa and a 1.5 Sonnar restored by Henery as the 1.5 Sonnar wasn't readily available for my Leica gear!

Well, I guess I'm going to have to save my pennies!

If they would only make the the 85mm f/1.4 in Olympus OM mount I would ignore the new Sonnar 1.5!
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Oooh, I'd sell my left something for that.

OMmmmmmmmmm
 
Avotius said:
hm....not liking that .9m min focus, and also 46mm filter is sorta an oddball to find and the wide open mtf is a little all over ther place suggesting the contrast will be somewhat lower wide open but if its cheap ill keep my eye out for it instead of a 50 summicron.
Click to expand...


46mm filters oddball? I have lots of 46mm filters, use them on my Contax G 🙂
 
aoresteen said:
Bad news indeed! Last year I spent a fortune having a Contax IIa and a 1.5 Sonnar restored by Henery as the 1.5 Sonnar wasn't readily available for my Leica gear!
Click to expand...

Isn't there an adapter from contax rf mount to leica m/screw mounts?
 
My (somewhat older) Jupiter-8 in Kiev mount has the same diaphragm shape (a newer sample that I have, in LTM, does not however). Bokeh on that lens is very nice...
 
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