Since I installed Nitdroid, when I open "photo's" I see a lot of thumbnails, icons, crap etc.

This is because Maemo looks for every image on the device + sd-card. When changing to "default camera folder" I only see the photo's I made. That is what I want.

But is it possible to tune some settings so that when I open "photo's" from the menu it only loads my default camera folder, so that I don't have to change it manually every time I want to look at some photo's?

try the app tracker-cfg

it allows you to select which folder your device should index. you can select only camera folder.

This worked, thank you!