photography

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).

I recently bought an Arsat H 50/1.4 lens for my Nikon DSLR. It is a cheap lens (<100$), however it is not really easy to find. Some items can be catched on ebay.

This lens is a soviet copy of the Nikon 50/1.4 standart AI-S lens. The build quality of the lens is not comparable to high quality Nikon lenses. Anyway, the lens is fully made of metal and it feels like a solid rock. the zoom ring is smooth but the aperture ring seems a bit fragile. The engravings indicating the aperture and the focus distance are dumpy. The rubber band of the focus ring is a piece of crap : it is poorly assembled to the focus ring.

At wide open aperture, the lens suffers from excessive loss of contrast thus resulting in dreamy pictures, especially when using it focused at the infinite. The image below is a 1:1 crop on the center of a shoot at 1.4 focused on infinite :


Stopping down to 2.8 helps a lot :


I've not done strict resolution tests, nonetheless, the center performance seems to be very good from 2.8 to 16, but border performance is only good from 5.6 aperture. At wide open aperture, the border resolution is awful, and the center resolution is not so good : the lens seems to suffers of high diffraction/reflexion in it (as shown in the above image), using it in low contrast and low light condition helps here.

Even if this lens is far for perfect, it is still a very funny lens to use and some good pictures may be produced with it. Here are some sample pictures that demonstrates that a reasonnable level of sharpness can be reached with it :



Above pictures have been taken with aperture of 1.4 & 2.8.

Go to the about:config page, search for an entry called gfx.color_management.enabled, if it does not exist, create this entry as a boolean. Then, simply set this to true and restart you're Firefox.

This workaround has been tested successfully on Firefox 3 Beta 4, and may not work with previous versions.