You can find many Go photographs from the Mainichi Shimbun here (with great thanks to kokiri and his 2009 post on SL).
The site shows relatively low resolution thumbnails (which can be extracted with screenshot) and offers to sell their full-resolution originals. They also supply higher resolution photos with watermarking.
Here are some examples.
Iyama in thought
Sumire using her laser vision
Games in kimono
Apparently there are also very old photographs if one scrolls down far enough. They can possibly also be accessed by date searching; I haven’t tried. Anything published by a Japanese newspaper before 1968 is, I believe, now in the public domain (which is, ofc, not to say that you won’t still have to pay).