My failure to visualize the background. I get so mesmerized by the image focus that I forgot how bright the out of focus background was.
I jumped right in trying to make a "fine print" on fiber paper. I made a good contact sheet, but after that I should have continued to work out the print on rc paper.
Got in a rush.
Any SLR, I don't spend enough time looking at the image stopped down to the actual aperture.
This is something shooting an enormous camera like 14x17, with 2 exposures per expedition forces you to do. Even then it's easy to miss something.
I need to shoot from a tripod that would help. At least help to slow me down.