CONTAX CLUB Carl Zeiss 討論區

I read from fredmiranda forum about D21. Someone quoted a Italian web site that D21 used some exotic glass which is no longer available. As a result, the same lens formula cannot be reproduced in ZF. Anyone know Italian can confirm this or any other source has similar information?

Source: http://www.fredmiranda.com/forum/topic/605260

不甚同意.....因為:

1. D21/2.8 推出的時間為 1994 年(請參考 http://zeiss.hp.infoseek.co.jp/1994.htm), Carl Zeiss 在該年份應該不會冒險採用供應不穩定的源採料, 畢竟一支 Carl Zeiss 鏡頭的 Product Cycle 動輒十年以上, 甚至數十年.....

2. D21/2.8 可稱為第一代 Apo-Distagon, 而第二代則為 CONTAX 645 的 D35/3.5, 第三代應該是 Hasselblad V-System 的 CFE40/4 IF, 而 CFE40/4 IF 至今尚有生產, 證明 Apo-Distagon 的血統應該不受環保問題物料的影響

3. 現今 ZM 系列已經有 Distagon 15/2.8 及 18/4 兩支全新設計 Distagon 鏡頭 (Retro-focus Design), 既然如此生產 ZF Distagon 21/2.8 應該相對更加容易, 只期望第四代的 Apo-Distagon 能持續改善 Flare Control 的表現

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Wah
理事 - Board of Members
www.flickr.com/dicksonlau

From what I read, the exotic glass in D21 means the glass elements containing Cadmium, Arsenic and Lead, not those in the legendary lens with radioactive elements. Cd, As & Pb are banned due to RoHS which is effective from 2006 (initiated at around 2002 and it is well after the design of D21).


The author did mention about D35/3.5 which is also based on the same design (APO Distagon). But without those banned glass, he said the performance is clearly inferior especially in tangential resolution. I know it is not fair to compare a 135 lens with a 645 lens. But the MTF diagram of D35/3.5 does show that the tangential resolution is not as good. BTW, where can I find the MTF of CFE40/4 IF? Is the one at zeiss.com IF version?


From the lens diagram, I think the 2 ZM Distagons are not a 'APO-Distagon' design.

Definitely I would like Zeiss to issue a new ZF21 with the same, if not better, high standard of CY21 and with better flare control. But the history has told us what has been changed after banning those polluted glass. If I let you choose, do you want a SWC/M or 905SWC?

Here it is:

http://www.zeiss.com/C12567A8003B8B6F/E ... 4966_e.pdf

Comparing with D35/3.5 the design featured with 1 more glass element (from 11 to 12), but still with less element than D21/2.8 design (15 elements)

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Wah
理事 - Board of Members
www.flickr.com/dicksonlau

Thanks, wah. Look at the dotted line.

The Italian homepage did make a good comparison:

http://www.luciolepri.it/lc2/marcocavin ... 00_pag.htm

I also noticed about the characteristic of the tangential lines of the D35/3.5 and D40/4 IF to be different from D21/2.8

For sure I know that for the MTF values it always must be the higher the better. However, how should the resolution of the two lenses to be different if they have the same value on the san line but different value on tan line? I had heard that one of the difference would be related to the rendering of the bokeh, but I do think there should be more........

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Wah
理事 - Board of Members
www.flickr.com/dicksonlau

The Italian homepage also provided a study on the PC-Apo-Distagon 25/3.5, in which glass with refractive index as high as 1.92286 was used!

http://www.luciolepri.it/lc2/marcocavin ... 01_pag.htm

For your information.........The famous 900403 to be used in Noctilux 50/1.0 is 1.9005 "only"

Also the PC-Apo-Distagon do show departed tan and san lines after 20mm radius of image circle. So the MTF characteristics of the D35/3.5 and D40/4 should be a result of a simplified design with less element? or actually is the limitation on the design on Apo-distagon especially for application with larger image circle?

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Wah
理事 - Board of Members
www.flickr.com/dicksonlau