This is the third mirror lens I have had, and I had terrible experience with the previous two. Unsharp, lacked contrast, dark corners, uneven sharpness, etc. Frankly, I bought this one all because it came with a Pentax KA mount, which by itself, almost pays for the lens if sold on eBay :-)

One of the best features of this lens is the close focus capability. It can focus as close as 1.7m, and a magnification ratio of 1:3.7. This is a remarkable feat to accomplish for a mirror lens.

After a few test shots, I was surprised to find that this lens is very sharp, and not vignetting, and contrast is excellent. This lens is not to be used handhold without some sort of stablization. The first few pictures in this gallery were taken with a broom stick found at the backyard as a mono-pod/tripod that I should have brought. It really did help, but still, getting sharp pictures was not easy.