@bf3cb02a, I think I noticed the Nikkor/Takumar contrast difference a couple weeks ago when you were posting Nikon and Pentax photos interspersed with each other. I found I was quickly able to spot which was which before reading your notes. 

 @b8889edb I might go back and check. It could be the lens, or maybe the film, ISO rating and developer.  With film photography there are so many variables!