Focus
I made a mistake that I took a many out-of-focus picture in Portugal.
When I was checking films I noticed some photos is defocused about 15cm behind. I think that out-of-focus is made by two reason; my error or camera problem.
If my Rolleiflex has a trouble, I have to ask for my favorite repair shop to fix it.
So I took a photos and develop by myself to check focus of my camera. In the result, my camera is no problem. I focused eye of totem pole and almost good result.
I'm sure it's OK as long as it is done carefully.
Idleness is the devil's workshop.