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The Hartblei (Zeiss) 120/4 Makro-Planar optical design is optimized for close-up in the 1:2 to 1:20 range eg a “flat field slightly larger than a human head with intricate detail”. The tests on this page are outside that optimal range eg in the 1:50 range. However, the Zeiss description claims excellent performance even at infinity.
Although the specifications indicate a reproduction ratio of 1:4.5, that is specified for an image size of 55X55mm. On a 35mm DSLR, that equates to about 1:2.9.
The MTF charts (Zeiss and Hartblei) suggest a nearly flat field, with a trace of astigmatism near the edges and corners of the shifted area (as used on a DSLR). Contrast of coarse structures (10 lp/mm) is somewhat low on the MTF chart, and this is apparent in the results. Micro contrast is good for the full 56X56 frame, but not particularly notable; the lens offer very balanced performance everywhere.
Contrast is moderate, but consistent across the field, with only a modest drop-off into the extreme shifted corners. Distortion is absent, and vignetting is low.
The results show that with a flat (planar) subject:
- unshifted performance is excellent over the entire the 35mm frame;
- fully shifted, full resolving power is maintained out to the extreme corners, though contrast drops a bit towards the periphery
- chromatic aberration is absent;
- peak contrast is seen at f/8 for central areas, and f/8 - f/11 for the periphery.
- Contrast and resolution hold up very nicely at f/16, and results at f/22 are still very good.
Excellent, balanced performance over a larger image circle.