Seaham docks | Stock Photo | iStock.

The Contax/Yashica Carl Zeiss Sonnar 135 mm f/2.8 lens is a very good lens for taking photos. However, if you look around the web, you might think this is not true. You often find bad photos or bad “tests” for this lens. This happens mostly for two reasons:
- testing a lens properly is difficult,
- testing a lens on film (this lens was designed for film) is expensive – much more costly than writing a few lines on a blog, indeed.
I photographed the Seaham docks with the Sonnar mounted on the Sony NEX-5 camera: a very poor performer! This lens, on digital, creates plenty of nasty false-coloured out-of-focus areas (I guess this is due to spherochromatism, I am not sure). This lens, on digital, is a very poor performer. I had to spend too long time to correct this image and make it good.

On the other hand, the photo of the traffic in Newcastle was taken on Ektar 100 film, and only minor correction in Photoshop was necessary. This Sonnar, on film, is a very good lens.