Arsat 50/1.4 - Resolution Tests

I've done some tests today using a ISO-12233 resolution chart.

It confirmed my first impression :

At wide open aperture (1.4), the border resolution is poor and the center suffers of very high pronounced chromatic abberations : high contrast figures are rendered with a purple, yellow or cyan glare that can be as high as 10 pixels.
Stopping down at 2.3 helps : the center is sharp, scratching the resolution of the 10M pixel sensor of the D40x. The border are still soft.
At 5.6 aperture, the center reaches the sweet spot of the lens, the borders are still a bit less sharp, but nothing to worry about.
An aperture of 8 is uniformizing the lens performance everywhere in the picture : however, the resolution of the center (and thus the border) is still a bit under the one of the center when stopped down at 5.6.
At 16, a mild quality drop can be observed in the center as well as in the border.

Vignetting is a non issue when using 2.8 or higher aperture settings.

Yellow/cyan chromatic abberations are present at all aperture settings. But this is generally not a show stopper here.

The lens also shows a quite high barrel distortion (I've nothing to measure this, but it seems high for a standart lens, maybe around 1%).

To conclude, this lens has a bad optical design, this is not a big surprise here as it is a (cheap) russian copy of a regular nikon lens. However russian engineeners have fogotten to include some features in this lens such as multicoated optical elements that would have helped in reducing chromatic abberations, at least at ultra wide aperture settings. Buying a regular 50/1.4 Nikon AI-S lens seems to be a better choice, even if the price of such a lens is a bit higher (>150$ or more for an used one).