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| Zeiss Contax MTF Comparison |
| 35mm Comparison |
| 50mm Comparison |
| 70-100mm Comparison |
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The following data was compiled from independent MTF tests of Zeiss Contax lenses previously published here. Centre and border measurements were taken at every aperture (here represented in our conventional Zone A and B format, as it remains unknown whether the 'border' sample point lay in Zone B or C). Marks out of ten were awarded. The highest possible grade appears to be 9.0, but in fact one lens appears to have performed so outstandingly at one aperture that it gained a mark of 9.1. Amps to 11, then. You may or may not be surprised to learn that it was the cheapest lens they tested.
It has long been our contention, based on real-world experience, that the Zeiss 21mm would have achieved a grade in excess of 4.4 had it been tested by photodo – unprecedented for a sub-35mm lens. These MTF figures appear to support that position.
Lenses compared in the 18-28mm focal length range:
• Carl Zeiss 18mm f4 Distagon
• Carl Zeiss 21mm f2.8 Distagon
• Carl Zeiss 25mm f2.8 Distagon
• Carl Zeiss 28mm f2.8 Distagon
| 18mm / 2.8 | 21mm / 2.8 | 25mm / 2.8 | 28mm / 2.8 | 28-85mm | |||||||
| A | B | A | B | A | B | A | B | A | B | ||
| f2.8 | | | 9.0 | 7.0 | 6.8 | 4.8 | 8.4 | 6.6 | | ||
| f4 | 7.7 | 5.8 | 9.0 | 7.9 | 8.8 | 5.2 | 8.8 | 7.6 | 8.3* | 6.1* | |
| f5.6 | 8.7 | 6.2 | 9.0 | 8.4 | 8.8 | 5.5 | 8.8 | 8.5 | 8.7 | 6.8 | |
| f8 | 8.6 | 6.4 | 8.7 | 8.2 | 8.7 | 5.3 | 8.6 | 8.4 | 8.6 | 7.0 | |
| f11 | 8.1 | 6.5 | 8.3 | 7.8 | 8.2 | 6.0 | 8.3 | 8.1 | 7.8 | 7.6 | |
| f16 | 7.7 | 6.0 | 7.5 | 6.8 | 7.8 | 6.2 | 7.7 | 7.5 | 7.8 | 6.8 | |
| f22 | 6.9 | 5.3 | 6.6 | 6.1 | 7.0 | 6.0 | 6.9 | 6.7 | 7.0 | 6.0 | |
| Distortion | -1% | -3% | -2% | -2% | -3% | ||||||
| Vignetting | 0.60 | 0.45 | 0.90 | 0.70 | -0.25 | ||||||
* Zeiss 28-85mm tested at f3.3
Fully validating the reputations of Distagon 21mm and the 25mm, these MTF measurements demonstrate just how good the 21mm is: recording ultimate figures centre frame (Zone A) at all apertures up to f5.6, and high scores throughout. The 25mm, by contrast, is dissected and found wanting: excellent performance centre frame from f5.6 up, but frankly poor Zone B performance at every aperture. Similar full frame performance was shown by earlier 16:9 tests of the updated ZF design.
The Contax 28mm f2.8 also confirms its status as the 'working aperture' wide angle of choice with impeccable performance from f5.6 and up. It isn't a wide aperture wonder (like the Leica 28mm), but stopped down a bit it outperforms even the legendary 21mm. What the distortion figures don't reveal is the complex waveform distortion pattern of the Zeiss 21mm which can only be corrected by a specialist application such as PTLens. Unfortunately, the 'Hollywood' 28mm f2 lens was not tested.
Last, and least, the data on the 18mm is as damning as the real world tests: it's a fine looking lens, until you look outside the A Zone. Ideal for APS-C sensors, then. It does sit well within the pattern, though: high resolution = high distortion; lower the resolving the power of the lens, and it can be well corrected in other areas.
