Stain-like visual artifacts

[u/Xzimnut]

Hi folks! I’ve picked up pinehole photography a few weeks ago. I’m still making lots of mistakes but in general, I feel like I’m progressing and I know what to do next time to avoid errors I noticed in previous pictures.

However, I run into one particular issue consistently and I can’t find any answer for this one: all my pictures have a sort of stain/visual artifact where the luminosity is lower than the rest of the scene. I’ve attached some of my pictures to illustrate what I’m saying.

Does anybody know what it could be? I was wondering that maybe the product for developing is not prefectly mixed. I don’t have all the details but the one I use is a powder made of coffee byproduct that I mix with water.

Thanks in advance for your help!

[u/_eagereyes_]

The last one looks like an intentional effect some people make by carefully just putting developer on part of a piece of paper at first :) What developer and fix are you using, and are you agitating during development? I assume this is paper, not film, right?