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mfs
01-06-2005, 16:49
I just spoke to the Hasselblad office today inquiring about the availability of the new CZ lenses. I am thinking about a RD-1 with the 21, or 25 mm CZ lens (FOV - 35mm). This would be about 50% of thr Leica equivalent lens.

The lenses (all but the 15mm, 21 mm, and 85 mm) are expected to arrive in early Feb. I asked about who actually builds the lenses - the Hasselblad person didn't really know. I suspect that Cosina builds the lenses under license from CZ - much like Kyocera, or Rollei.

Does CZ supply the individual elements???
I believe that Cosina builds the the exterior of the lens.

It would be nice to know if CZ inspects each lens for QC after assembly

Martin.

jlw
01-06-2005, 17:38
Probably about all the information you are going to get is here. (http://www.zeissikon.com/faq.htm) (Read toward the bottom for lens info.)

Nothing to worry about there, IMO. Cosina has proved they can make excellent RF lenses at a moderate price point. Just think what they'll be able to do with lenses that can command a higher price!

iMacfan
01-07-2005, 02:47
From what I have heard, the CZ designs are pretty retrofocus, which is exactly what you want with a digital sensor to minimize the angle at which the light hits the sensor.

Huck Finn
01-07-2005, 06:56
Originally posted by iMacfan
From what I have heard, the CZ designs are pretty retrofocus, which is exactly what you want with a digital sensor to minimize the angle at which the light hits the sensor.


IMacfan, I too have read that the ZI system is designed for a quick jump to digital. However, although the Distagon design of the 15 is retrofocus, the Biogon (4 of the lenses) & Sonnar designs are decidedly not retrofocus. Maybe someone with more technical knowledge than I can clear this up.

jlw
01-07-2005, 09:17
True retrofocus ("inverted telephoto") wide-angle lenses can be spotted by the fact that the front element or group has a negative curvature. I haven't seen diagrams for the Z-I lens designs, so don't know whether or not this is the case for these.

Even if not a retrofocus design, there are other tricks the designer can use to improve evenness of illumination, so we wouldn't want to rule out these lenses for digital-camera use until we've seen them "in the glass."

Huck Finn
01-07-2005, 14:40
Jlw, you can find the ZI lens diagrams at www.zeissikon.com Under "Downloads."

I think that the term "retrofocus" has also come to be loosely associated with with lenses for which the back focus is equal to or greater than the focal length, another characteristic of true retrofocus lenses. I don't know if this is a factor in the confusion, specifically since these Zeiss lenses seem to be a little longer than other RF lenses.

stevew
01-07-2005, 18:56
We like rangerfinders for their compact lens amoung other things. It seems unfortunate that a lens that is designed for straightening out the rays for digital, is going to be physically larger. The nikkor digital slr 12-24 lens could be mounted on a rangefinder via adapter but it would be huge.

jlw
01-07-2005, 21:48
Huck, thanks for the link. I downloaded the PDFs for the 15 and 21; both have strongly negative front elements, so I'd say they qualify as retrofocus designs.

Incidentally, another advantage of these (in addition to better evenness of illumination) is that generally they have larger maximum apertures than wide-angle lenses of conventional construction.

So, you can have a smaller lens with lower distortion, OR a larger, faster, more evenly illuminating lens. Oh, well, if you can't have it all, I guess it's nice at least to have a choice!

Huck Finn
01-08-2005, 03:53
Originally posted by jlw
Huck, thanks for the link. I downloaded the PDFs for the 15 and 21; both have strongly negative front elements, so I'd say they qualify as retrofocus designs.

Incidentally, another advantage of these (in addition to better evenness of illumination) is that generally they have larger maximum apertures than wide-angle lenses of conventional construction.

So, you can have a smaller lens with lower distortion, OR a larger, faster, more evenly illuminating lens. Oh, well, if you can't have it all, I guess it's nice at least to have a choice!

Yes, the 21 Biogon does have a negative front element, but it does not have a positive rear element that is also characteristic of retrofocus design. The 15 Distagon is a true retrofocus lens.

In regard to these lens designs, Zeiss claims that they are sharper partly because they "minimize focus shift." Any idea how these designs do that?