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(註:最近有朋友提及敝 forum有一些關於 “Sonnar” 設計 (e.g. S50/1.5) 的討論文章,提議把這些文章置頂以方便閱讀,敝會當然樂於和大家分享!由於每位原作者皆花了不少心機才寫成文章,各界如需引用,敬請指明原文出處和預先通知敝會,謝謝!)

原文請見文章:
http://forum.contax-club.org/viewtopic. ... sc&start=0
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wah 寫:
Terry Sham 寫:
其實當時Oskar Barnack在Ur-Leica用上Kino-Tessar 50mm有什麼不滿, 要開發Summar? :roll:


小弟唔係光學專家...........不過既然係 Leica 野就用番 Leica 界權威 Erwin Puts 既言論討論一下.......

1. Leica M-lenses

http://www.leica-camera.com/imperia/md/ ... tem/49.pdf

在 Page 42, "The first lens used for the Ur-Leica had a focal length of 42mm. Commercial models (from 1925) were fitted with the Anastigmat/Elmax f/3.5/50mm. This design had 5-elements, presumably to avoid patent conflicts with the Zeiss company........."

小弟對於 Kino-Tessar 50mm 既質素當然未能理解.........不過世界上就真係一樣唔知係造福人群定係遺禍人間既發明.........就係叫 patent

想當年 Elmar 50/2.8, Elmar 50/3.5 既設計都係以 Tessar 為藍本.........不過光圈位置就與 Tessar 不同, Leica 的設在第一組與第二組之間, Tessar 的就在第三組與第四組複合鏡片之間. 對於此設計, Erwin Puts 有此評論:

(同樣 Page 42) "The Elmar f/2,8/50mm was introduced in 1957, almost 33 years after the Elmar f/3,5/50mm. In its day, the Elmar f/2,8 was famous for its very good image quality in the center. It was also slightly ahead of perennial competitor Zeiss
with the Tessar. The different position of the aperture (between the first and second element) was the main advantage of the Elmar. On test the Elmar performs acceptably, at full aperture with a low overall contrast and clearly rendered fine details with smooth (more accurately: soft) edges..........."

當然 Elmar 係不少 Leica fans 既摯愛........由其以 Red-scale version 最受追捧! 是由於使用稀土玻璃之緣故..............小弟則相信, 以 Tessar 此相對簡單之設計下, 對於鏡片組裝與鏡片質素上既要求其實更高, 任何廠家 (Voigtlander, Nikon, Canon) 只要有誠意制作個人覺得質素不會相差太遠.

而當年的 Voigtlander (未被 Zeiss 收購前)既 Skopar 都係用 Tessar 既一套...

http://www.taunusreiter.de/Cameras/Bess ... to_dt.html

不過.........既然 Leica 係製造 Tessar 一類鏡上有如此獨門秘方..........小弟就不知如何解釋其後推出既 Elmar-M 就用回 Tessar 既設計..........或者係 original Elmar 既設計生產成本高昂? :roll: :o

另外一個解釋係..............Tessar 係 2002 年慶祝 100 歲生日 8)

2. 至於1933 年推出既 Summar 50/2 (參考 LEICA LENS 不朽之名玉 203, Page 104), 其根本 design 就是 Double-Gauss, 以當年 35mm 相機市場計, 由於 coating 問題, 以 Double-Gauss 所設計既大光圈鏡由於玻璃介面比較多既關係 (如 Summar, Xenon, Summitar 一類) 一直被 contrast 較高, Flare 及 玻璃介面比較少的 Sonnar 50/2 及 Sonnar 50/1.5 所比下去. 不過以市場先決原則, 就算性能上是以 Elmar design 佔優, 但又怎可錯過大光圈標準鏡的市場 (以當天 ISO 50 為高速菲林計............)

Terry Sham 寫:
可否解釋暗位起沙其實是什麼原因? :roll:


參考 Erwin Puts 的 homepage 上文章:

http://www.imx.nl/photosite/japan/voigtl01.html

"A most interesting phenomenon became visible with these side-by-side-shots. The Skopar gives images with a grainier pattern and with grain clumps that are rougher than when the Leica lenses are used. This is caused by the higher aberration content of the Skopar lens. When aberrations are abundant the light rays emanating from a light point source do not converge to one point in the image but have a more random pattern around the central core. These more widely spread rays energise more silver grainaround the center spot and randomly so. A rough clumping is the result. "

小弟記憶所及 Erwin Puts 曾經有篇文章討論過新一代 Leica (尤其ASPH) 與早一代鏡頭之比較, 當中有提及過新鏡的暗位比舊鏡更黑, 是由於 ASPH 鏡的 higher aberration 抑制得更佳之緣故 (此解釋對於我一眾老鏡 fans 當然完全不能認同), 不過以 Erwin Puts 先生的光學設計立論來說, 可以嘗試討論一下原因:

1. Sonnar 的設計本身就缺乏 Planar (Double Gauss) 設計上的優點, 就是有很多光學上的 aberrations 已經於對稱設計上所抵銷, 以現代鏡頭的絕佳 coating 計, Sonnar 設計於 Contrast 上的優勢上當然已經不怎麼大, 而於大光圈時對於 higher aberration 之抑制當然比 一般 Planar 設計為差, 此情形於遠離中心位置更甚!可參考 Cosina homepage 上的ZF Planar 50/1.4, ZM Planar 50/2 與 ZM C Sonnar 50/1.5 MTF 作比較:

http://www.cosina.co.jp/seihin/co/zf-50/index.html

http://www.cosina.co.jp/seihin/co/p-50/index.html

http://www.cosina.co.jp/seihin/co/c-s-50/index.html

當中可見 C Sonnar 之 40lp/mm 線於 f/1.5 時得分明顯比 Planar 50/2 為差 (當然 f/1.5 比 f/2 是十分重要的因素.....), 比 ZF Planar 50/1.4 亦為差 (於 f/1.4 時 40lp/mm 線比 C Sonnar 好一丁點, 不過重點是實線於虛線十分貼近, 是 Planar 之 Field Flatness 為佳的另一證據 :o )

相反, C Sonnar 的特性 (或優勢?) 是於全開光圈時 10lp/mm 線 與 20lp/mm 線得分普遍為高, 或許這是 Cosina 此輯試鏡照所決定採用全開光圈拍攝的原因, 而試鏡照 No.2 為 f/1.5 1/2 光圈 (縮半級), 個人覺得暗位起沙的問題比 No.1 與 No.3 已有所改善

曾經有某位本地攝影界前輩與小弟分析 Summicron 50/2 與 Elmar-M 50/2.8 拍攝人像之特色時, 以膚色較滑來形容 Summicron, 以感覺上較 "sharp" 來形容 Elmar-M (又是 Contrast vs Resolution 問題), 說穿了就是 Double Gauss VS Tessar 之普遍特色上的分別

2.另一個解釋與鏡頭設計無關, 只輯相片以正片拍攝, 而 model 為主體的 exposure 明顯比佈景高出很多, 相片 scan 後以 jpeg format 載出.

以普遍用負片的玩家來說, 或如果有做開 film scanning 的朋友或許會感覺到, 問題在於:

* 一般情形下以負片粒子比正片幼細 (此輯相是以正片拍攝)
* 普遍負片比正片的寬容度高
* 以小弟的經驗而言...........正片 + 暗位 時的粗粒子問題尤其嚴重
* 相片 output compression 的問題

以上各點有關 Digital 問題要請 Franka 大大出手 8)

_________________
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* * * * * *
鯨魚愛Zeiss
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文章發表於 : 週三 21 2月 07 00:07:51 
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註冊時間: 週日 09 11月 03 00:26:48
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wah 寫:
Terry Sham 寫:
多謝阿Wah講解, 又受教了, 明了許多, Double Gauss 同 Tessar 的設計今天不論在德國鏡, 日本鏡, 甚至大陸鏡上都會找到, 但推出135當時, Carl Zeiss都是設計及生產比較大片幅的鏡頭為主, 所以Leitz把鏡頭作出對細片幅的優化, 有沒有這樣的學說?


這問題應該歸納為 135 系統發展史之研究...............恕小弟手頭上沒有太多資料 :o

個人覺得由於 Leica 決定專心於 135 系統, 所以對於推動 135 片幅之鏡頭發展當然有不可抹殺之功勞!

參考一下 Stephen Grandy 的比較:

http://www.cameraquest.com/zconrf1.htm

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

Leica 與 Zeiss 的競賽始終好像不斷的追與逐, 無疑 Leica 於 135 發展上有著其前瞻性, 不過 Zeiss 始終是一家比 Leica 大得多的公司, 要顧及的產品種類多不勝數, 對 135 系統的專注當然亦不及 Leica, 可是當其下決心發展 135 系統時, 憑藉龐大的資金與技術, 又能推出比 Leica 出色的產品

由 Contax II 開始, 到 III, 戰後的 IIa 及 IIIa, 個人覺得於 engineering 上絕對比同期的 Leica I, II 及 III 優勝, 直到 M3 之推出, Leica 至方可完全稱霸於 135 Rangefinder 市場, Contax IIa / IIIa 於五十年代中期退下火線後當然還有來自 Canon 與 Nikon 的挑戰.

http://www.imx.nl/photosite/japan/rangefinders.html

每個人有其黃金年代, 於相機系統亦然, Contax 的黃金年代由 Contax II 起, 到 III, IIa / IIIa, 所以經典的鏡頭亦是出於這時代, 好像 Biogon 21/4.5, Biogon 35/2.8, Sonnar 50/1.5, Sonnar 85/2, Sonnar 180/2.8 等, 在於廠家而言, 系統的成功代表更加多的 sales volume, 亦有足夠的理據去投放更多 R&D 資源, 是十分合情合理的發展策略.

在於 Leica 而言, 其黃金年代絕對是 50 年代中期起於 Leica M3 推出市場後, 至 M2 及 M4 的年代, 自始 Leica 就是最高級 135 RF 機的代名詞. 由於有市場上的絕對優勢, 出於此年代之鏡頭亦是一代經典, 如 Summicron 35/2 8-element, Super Angulon 21/3.4, Noctilux 50/1.2 等.

Leica M 系統當然有其黑暗期...........由 M4 後, M5, CL, M4-2 及 M4-P 一直都不是十分成功的產品. 根據 Erwin Puts 所說由 1980 年到 1993 年 M 系列根本沒有新鏡頭設計推出市場 (Page 60, Leica M-lenses). Leica 於此時期專注於 135 SLR 的發展, 不過由 R3 到 R7 的機身可能一直活於 Minolta 的陰影下, 所以並不受 Leica fans 的歡迎, 而小弟最愛的 Leica SLR 機身始終是 Leicaflex 系列 (尤其是 Leicaflex SL2), 其次最好的 SLR 機身個人覺得是 當今 R8 / R9 (當然以 R8 最超值!).

同期的 Zeiss Ikon Contarex 系統, 以相機業界而言每期機身都是當時最先進的設計, 由 Contarex I 的 連動測光, 到 Super 的 TTL 測光, 及 Electronic 的電子 shutter 與 AE 光圈先決功能, 在今天看來是完成度不是最高的設計, 不過若沒有 Zeiss Ikon 行出第一步, 何來有其後更完善的設計?

Contarex 的鏡頭群在於小弟立場而言, 是可以任選一支都絕不後悔的唯一系統, 當然喜愛就要接受 (忍受?) 其機身設計................或可選用 Canon FD 機身改 mount..........不過個人覺得就欠缺完汁完味的感覺 :wink:

其後由七十年代中期起, 黃金年代是屬於 Nikon 的 F2 / F3, 一直到今天的 Canon EOS........

未來, 又不知是怎樣? :o

不過, 以小弟的感覺而言, 喜歡 Leica 始終比喜歡 Zeiss 容易.............

要做一個 Carl Zeiss 既 fans, 相對要做更多的功課與研究, 有更深入的了解後, 愛得就會越深 8)

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鯨魚愛Zeiss
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FR 寫:
wah 寫:
vincenthoy28 寫:
jason.lau 寫:
I thought that Leica should reintroduce its classic design lenses, such as 35/2 8-element, 50mm DR, 50 Elmar red scale, etc in today market. Simply use the old formula and sell the lens. When an old 8-element can be sold from 15k to 20k today, if Leica reintroduces it again with the price tag of 20k, I think many people would still rush for buying it.

I think this is almost impossible la.......since all the lens element become lead free, Leica are required to redesign the lens element to suit this situation...

So as C Sonnar 50/1.5 is a new design as well!

Yes, at least I think its so, the Classic Sonnar is a hihgly developed deriative of classic triplets with the characteristic sage of " Strong Interface " - the new 50/1.5 can be termed a hybrid design where the designer clearly shine from the complex front 2 groups and utilize 1/2 of a planar design to go with it but utilize the same corrective rear group. in fact if one look carefully, one can see that the rear corrective group is more akin to a rework of th old 50/2.0 sonnar / Tessar rear group by splitting the rear most element ...

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文章發表於 : 週三 21 2月 07 00:18:21 
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arnopoon 寫:
Some more comments from Luminous Landscape:
http://www.luminous-landscape.com/reviews/lenses/zeiss-m-mount.shtml

UPDATE From Carl Zeiss:

When the review of the 50mm Sonnar was first published there were some rather derogatory comments made on an online forum about our review, because of the concerns we had expressed about the sharpness (or lack thereof) of this lens when used wide open.

I had contact Zeiss about our finding and was told that the lens tested would be checked and also that the factory would be contacted for their feedback. Below is their response, confirming the appropriateness of our findings, and explaining why this is the case.

C-Sonnar T* 1,5/50 ZM

Information about special features for dealers and users

The C-SONNAR T* 1.5/50 ZM is a very special lens; based on a classical lens design concept from the 1930´s. The additional letter “C” in the name of the lens expresses this designation.

This lens design helps to achieve pictures with a special artistic touch. This lens ‘draws’ your subject in a fine, flattering manner and is therefore ideally suited for portraiture. It renders a sharpness that is slightly rounded, being less aggressive than in contemporary lens designs, but at the same time not soft in its rendition.

Many famous portraits of glamorous and prominent people during the 1930´s used this technique to great effect. These images are characterized by portraying the person in a shining, nearly celestial way. This effect is very well balanced and not exaggerated; therefore many viewers see it in a subconscious way. The trained observer, however, understands the underlining technique and enjoys the results.

This lens design exhibits some additional effects, which should be understood to achieve the maximum benefit from the C-Sonnar T* 1.5/50 ZM:

Because of the above mentioned classical characteristic of the lens the best focus position in the object space can not be kept exactly constant for all f-stop settings.
The passionate photographer might notice a slightly closer best focus in his pictures than expected. When stopping down the lens to f/2.8 or smaller this effect is minimized, so the focus position will be as expected.
In order to balance the performance at full speed and other f-stop settings the lens is adjusted with above described characteristic.

The special features of the C-SONNAR T* 1.5/50 ZM are best used in emotional, artistic, narrative images, portraits or atmospheric landscapes. For documentation or technical subjects CARL ZEISS recommends to stop down the lens at least to f/5.6 or to use the PLANAR T* 2/50 ZM lens.


iamderek 寫:
1 more comment from Zeiss. The 1st & final part is the same as the last one.

The C-SONNAR T* 1.5/50 ZM is a very special lens based on a classical lens design concept from the 1930's. This is expressed by the additional letter "C" in the name of the lens. It helps to achieve pictures with a special artistic touch. This lens draws your subject in a fine, flattering, a little bit glorifying way. It renders a sharpness which is a little bit rounded being less aggressive than in contemporary lens designs, but not soft. A lot of famous portraits shot of glamorous and prominent people of the 1930's used this effect. It gives the portrayed person something shining, nearly celestial. This effect is very well balanced, not exaggerated. Therefore many viewers see it in a subconscious way. The trained observer, however, knows why and enjoys it.

Provided that the lens is used with f-stops wider than f/2.8 the images are a bit similar to images that one can get with the soft filter ZEISS SOFTAR. The C-Sonnar T* 1.5/50 ZM, however, avoids some disadvantages in these softeners in the out-of-focus background area. When one makes a lens with such features, one has to pay for that and has to accept the following side effects:

1. Compared to the PLANAR type of the same focal length the C-SONNAR is less corrected for a flat field.
2. The C-SONNAR T* 1.5/50 ZM has a distinct focus shift when stepped down; this means that the focal plane "wanders" when the distance setting remains unchanged but the lens is stepped down. this focus shift occurs particularly in the near range.

3. The depth of field at high apertures of such a lens is slightly higher than with modern designs.

Field curvature is not necessarily a disadvantage in shooting 3-dimensional subjects. The "wandering " of the focal plane needs special considerations. When the lens is stopped down from wide open to medium apertures, the focal plane in the object space is shifted toward the background. (For example: from 5 to 6 meters when the lens is stopped down to f/4). Therefore the rangefinder cannot be easily corrected for all f-stops.


The special features of the C-SONNAR T* 1.5/50 ZM are best used in emotional, artistic, narrative images, portraits, or atmospheric landscapes. for documentation or technical subjects CARL ZEISS recommends to stop down the lens to f/5.6 or to use the PLANAR 2/50 T* ZM lens.

_________________
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* * * * * *
鯨魚愛Zeiss
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