p.3 #1 · How do old Zeiss/Contax/Yashica lenses compare to modern designs?
Along with Leica, Sony is probably the most enthusiastic maker regarding aspherical surfacing, that is the background. Sony only mention the four asph elements in that 24-50 zoom. My somewhat educated guess is they use no PMO or PMC processing, but an extension of their very sophisticated glass molding processes.
The PMO/PMC process is most associated with Canon (and phones):
'Canon has been at the forefront of developing PMo lenses. For example, the RF28mm F2.8 STM lens features 3 large-diameter PMo aspherical lenses, contributing to high image quality while maintaining a compact and lightweight design.
Similarly, the RF 16mm F2.8 STM lens incorporates a single PMo aspherical lens to achieve excellent color rendition and crisp, contrasty images. The manufacturing process of PMo lenses involves injecting resin into a mold, which is then coated to finish the lens. This process is *more cost-effective*..'
Sony, however, devoted vast sums to developing and refining glass aspherical elements:
To my knowledge, only the 35/1.4 in the CY range uses just one asph lens. The CY 21/2.8 has none either among its 15 elements.
Jan 11, 2025 at 07:42 PM
Steve Spencer Offline • • • • • • • Upload & Sell: On
p.3 #2 · How do old Zeiss/Contax/Yashica lenses compare to modern designs?
philip_pj wrote:
Along with Leica, Sony is probably the most enthusiastic maker regarding aspherical surfacing, that is the background. Sony only mention the four asph elements in that 24-50 zoom. My somewhat educated guess is they use no PMO or PMC processing, but an extension of their very sophisticated glass molding processes.
The PMO/PMC process is most associated with Canon (and phones):
'Canon has been at the forefront of developing PMo lenses. For example, the RF28mm F2.8 STM lens features 3 large-diameter PMo aspherical lenses, contributing to high image quality while maintaining a compact and lightweight design.
Similarly, the RF 16mm F2.8 STM lens incorporates a single PMo aspherical lens to achieve excellent color rendition and crisp, contrasty images. The manufacturing process of PMo lenses involves injecting resin into a mold, which is then coated to finish the lens. This process is *more cost-effective*..'
Sony, however, devoted vast sums to developing and refining glass aspherical elements:
These are some of the top performing Zeiss C/Y lenses. It seems Zeiss didn't shy away from using Asph elements when they pulled out all the stops and they certainly used them later on their Otus lenses, several of their ZE/ZF/Milvus lenses and two of their best ZM lenses (35 f/1.4 and 15 f/2.8).
p.3 #5 · How do old Zeiss/Contax/Yashica lenses compare to modern designs?
rico wrote:
I never saw a CZ C/Y datasheet or brochure with mention of asphere elements.
Hi Rico,
I just checked my copies of the Zeiss datasheets. The CZ datasheet for the Distagon 35/1.4 CY says:
"Number of elements: 9 (1 aspheric surface)".
None of the datasheets for the other lenses listed above by @Steve Spencer say anything much about shape, but they do talk a lot about special ingredients ("extreme anomalous partial dispersion", "high-index glass", "fluophosphate glass", and etc.).
Screen shot of Zeiss datasheet for Distagon® T* f/1.4 - 35 mm
p.3 #6 · How do old Zeiss/Contax/Yashica lenses compare to modern designs?
jcolwell wrote:
"Number of elements: 9 (1 aspheric surface)".
Thanks for the correction, Jim. I don't own any 35mm CZ C/Y, and likely never perused the D35/1.4 spec sheet. For film, I had that FL covered by the T3. As you say, the D21 and AS200 spec sheets say nothing about aspheres, respite that Spencer listing.
Jan 12, 2025 at 02:35 PM
Steve Spencer Offline • • • • • • • Upload & Sell: On
p.3 #7 · How do old Zeiss/Contax/Yashica lenses compare to modern designs?
rico wrote:
Thanks for the correction, Jim. I don't own any 35mm CZ C/Y, and likely never perused the D35/1.4 spec sheet. For film, I had that FL covered by the T3. As you say, the D21 and AS200 spec sheets say nothing about aspheres, respite that Spencer listing.
I was just reporting what is in the pebbleplace database. It isn't my listing. I have no idea where they got the information for that site, but I do know that database was really useful once upon a time when I had a Canon 5D and 5D II and adapted Zeiss C/Y mount lenses. I always found the information to be both accurate and helpful, but maybe they got it wrong. I believe FM member John Black put the database together. I don't know if he ever logs into FM any more, but perhaps he will and let us know where he got the information.
p.3 #8 · How do old Zeiss/Contax/Yashica lenses compare to modern designs?
rico wrote:
Thanks for the correction, Jim.
More of an unpdate, IMO. Anyway, I'll be using my Contax CY lenses on Canon film cameras, in the near future. I just received the first of two, matching EOS 7 cameras that I recently bought. They'll be Port and Starboard.
I'm getting itchy to replace my old Contax 139Q camera (that I sold 15+ years ago), but I have to let the dust settle on my new EOS film setup.
p.3 #9 · How do old Zeiss/Contax/Yashica lenses compare to modern designs?
'..the Distagon 2.8/21 for the Contax SLR, a relatively complex lens with 15 elements in 13 groups. However, it had no aspherical surfaces. Its performance, particularly the perfect correction of lateral chromatic aberration, was achieved solely by the combination of very special (and expensive) high-index glass types with glass types displaying extremely high anomalous partial dispersion.'
Hubert Nasse, Carl Zeiss (Distagon white paper)
So Zeiss pushed hard on each of HRI and APD glass - 'very special (and expensive)', 'extremely high anomalous partial dispersion'. You don't hear much about HRI glass usage in lens specs these days, but the older Leica APOs (and now DZO/Thypoch) do list them separately from APD glass. From what Dr Nasse had to say above, it might be a factor in the 'modern vintage' 90s' look, for top tier optics at least, and may contribute to why these lenses have aged so well. The expense may have led to its properties being displaced by ever more sophisticated asph shaping (and PMO) and more affordable APD glass, to cover sensor outers effectively and eradicate LoCA.
'What is “partial dispersion”? This mysterious-sounding technical term is appearing with increasing frequency in brochures. If, for example, a negative and positive lens are combined to correct chromatic aberration, then the element with the lower refractive power must have the higher dispersion so that the color dispersing effects of both lenses compensate for each other without also canceling the refractive powers of both elements.'
'Glass types with anomalous partial dispersion deviate from the normal relationship between dispersion and the curvature of the dispersion curve. For them, the ratio of the change in refractive index between blue and green to the change between green and red differs from that of normal glass, allowing better chromatic correction with these glass types.'
p.3 #10 · How do old Zeiss/Contax/Yashica lenses compare to modern designs?
I get lazy looking after lenses. I just had a solid inspection of two of my 30-40 year old specimens, CY 35-70/3.4 and CY 100/3.5. Both are exceptionally clean, despite the proposed potential of the zoom to suck in air, it being a push-pull single ring design. They are as clean inside as my new CV and Thypoch lenses. Speaking of which, below a couple from 2009 or so, out of the Sony a900, shot through the (Leitaxed) CY 28/2.8, a simply lovely little lens. The current lot just don't seem to be able to do it so well. A modern one of this design would win many hearts, Carl Zeiss film lenses work great on digital.
..
corner crop - some thought we'd see a lot of smearing; check the CA, always a strong feature of CZ lenses
I believe there is a demon domiciled around this hut.
