Chasseurs d'Images 261: test of lenses.

Started Feb 13, 2004 | Discussions thread
Powerdoc Veteran Member • Posts: 3,542
Well i'll try to sumarrize it for you.

LM1 wrote:

I'm not asking you to translate the whole article, but you could,
maybe, give us some meaningful numbers from the article.

?

The test from CI are based upon DXO analyser from DO labs. Do labs is a french start up, with some brains in his scientifical comitee like Pierre Louis Lion 1994 Field medal.

The test procedure is indeed very simple. A picture of a pattern (made of black dots) is taken by a camera (with various lenses in case of DLSR) and the result is compared to a virtual pattern (a perfect image of the pattern if you want).

The DXO sofware analyser compare the two images, the perfect virtual pattern, and the one taken by the camera. 5 points are studied :

  • the noise

  • the vigneting

  • the geometrical distorsion

  • the chromatic aberration

  • the sharpness (and it's the most difficult part of this test) .

All this points are studied at various stop and focal lenses.

The sharpness is studied via the observation of the degradation of the dots of the patterns in various aeras. The more it's blurry the more the dot is streched or enlarged. This degradation is evaluated by a number the BxU (blur unit).

I must emphasis that this test study the whole system : both sensor/digital processing and lens. Thus it's possible to compare an APN camera with a SLR one. (concerning the bridge camera, the minolta dimage A1 was excellent).

CI choose to use JPEG fine folders by default (the results may be different with RAW, but no one know for the moment)

Some conclusions where made. Due to the smallest sensor both the D300 and D10 made better pictures in the corner than the EOS 1 DS : less vignetting, less distorsion, less chromatic aberration, and a better sharpness in the corners. All this results are indeed logical, because with the smaller sensor only the central part of the image transmitted by the lens is used, and we know that most of the times the center is better than the corners.

The canon L series gave pretty good results with the rebel and D10, but was a step behind of the EOS 1 DS (16/35 L and 17/40 L). The results where equally good (and indeed very good) with the 24/70 2,8 L and the 28/70 2,8 L . The canon EF 18-55 gave good results on a D300, althought it was a step behind a L serie. The 28-105 3,5 4,5 USM 2 gave very good results with the 10 d and rebel, and good results with the EOS 1 D.

Sigma lenses gave better results on a canon body, than a Nikon one, or worse the S2 (very strange indeed).
The Nikon lenses where a step behind than the Canon one.

On the french forum site of CI, this test provacated a little flamewar. Nikon and Fuji owners where very disapointed by those tests.

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