I don’t know the exact year or the venue the photo at the left was taken at. Probably around 1975. The photo below could have been taken at the same time. It has a similar backdrop. These may have been taken at a guest posing event near contest time. What is interesting about Schwarzenegger’s calves is that they look “thinner” from the front and higher set as well. There are a lot of photos of bodybuilders whose calves look bigger than Arnold’s do in that photo. However, from the back, it is a whole different story. From behind, Arnold’s calves look very three dimensional and bunch up into all kinds of gnarls and contortions( see below photo,right calf).
Regarding the gnarled look, Mike Mentzer had the same inner calf bump(see below). Developed enough, some bodybuilder’s calves have a peak on the inner calf like Mentzer does in the below photo. The bodybuilder who had the most developed inner calf peak was Matt Mendenhall. Check out the photo below Mentzer. Mendenhall’s small knee and ankle joints made his calves look all the bigger. Amazingly, Matt Mendenhall never went professional and is an example of one of the best bodybuilders who never got their “pro card”.