Posted by philou on Tuesday, February 9. 2010 at 23:28
In my previous post I discovered some strange things while playing on my two 50mm on a Nikon D700:
- at close focus the Arsat is wider than the Nikkor,
- the arsat seems sharper than the Nikkor !!??, even wide open.
So two days later, I've took some shoots of the same scene: a building at approx 30 meter of the camera. The Arsat has been focused using the telemeter of the d700 + multiple tests shots while the nikkor has been autofocused on the same focus point.
I confirm the Arsat is wider than the Nikkor. (so it is not an artefact of focusing systems)
- at f/1.4, the two lenses are sharp in the center (today I found the nikkor a little bit sharper), while the the border of the Arsat are poor, the Nikkor still has a good definition,
- at f/2 the center of the Nikkor leaves nothing to be desired, the Arsat is clearly below and still delivers crappy borders,
- at f/2.8 the Arsat is still behind the Nikkor in the center, the border of the Nikkor are very good and the Arsat starts to deliver better borders,
- f/4 is the same as f/2.8
The contrast of the Arsat is really poor wide open (the Nikkor is ok), it is better at f/2 and nice at f/2.8.
The Arsat showed a strong focus shift when stopped down. At f/1.4 it was focused at 30 meters, at f/4 the sharpest aera starts at 15 meters. This explains why when I bought this lens I discovered I had to turn the focus ring a bit after the telemeter confirmed the right focus to take pictures at f/2.8.
The Arsat also showed a huge amount of strange barrel distortion (the distortion figure is not centered).
The conclusion is rather simple: the Arsat is a bit crappy !
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