DxOMark review for the Nikon 24-120, the new constant f/4 aperture on DxOMark.

Tuesday November 23 2010

Lens Review
Introduction | Much more light | About resolution | Vignetting at wide apertures | Lateral chromatic aberration | Distortion | So… who is this lens good for?

Increased centre resolution…

The other feature that has been improved is the resolution, especially in the center throughout the zoom range. Reading the summary does not really show a tremendous gain: jumping from 58 lp/mm to 59 lp/mm when used on a D3X doesn’t sound so impressive. But a quick look at the graphs shows that things have changed a lot.
The old zoom was much more limited. Between 24mm and 50mm, you had to stay between f/5.6 and f/11 in order to reach the sharpest resolution. Above 50mm, you had to stop down to f/8 and even to f/11 to stay as sharp as possible.

Center resolution map of the 24-120mm f/3.5-5.6 on a D3x

The new 24-120mm, however, has a very good center definition at any focal length between full aperture (f/4) and f/11, except between 85mm and 120mm, where you have to shoot at close to f/5.6 to remain perfect. Overall, the new zoom is much more comfortable for daily use.

Center resolution map of the 24-120mm f/4: easily above 60 lp/mm on a D3x!

… But not very good in the corners

Center resolution is now very comfortable, and remains so for 1/3 of the field. But as soon as you reach 2/3 of the field, it decreases. To remain above 50lp/mm (on a D3X) you have to stick to 24mm f/8, and between 50mm and 85mm you must use apertures between f/8 and f/11. Fully opened, the lens falls under 50 lp/mm, and plunges under 40 at 75mm. In the corners, the situation is roughly the same.
So, in short, if you want your pictures to have as much definition as possible on their whole surface, the best focal length provided by this 24-120mm is between 50 and 85mm, at apertures within f/8 and f/11.

2/3 field resolution map of the 24-120mm f/4: the graph clearly shows the optimal area: 50–85mm at f/8–f/11.