Nikon D300 User Manual page 46

Current – This is the most limited playback mode available.
Whatever folder your camera is using currently will be
displayed during playback. No other images or folders will be
displayed. You might have a folder named 999D300S, or
555ND300, for example, and be using it for landscape
images. If you use Current, only that folder's images will
display when you press the Playback button.
My Recommendation: In my opinion, using anything
except All leaves one open for lost images. If you don't have
any other Nikon cameras around, this may not be a critical
issue. However, if you're like me, you'll have a series of
older Nikons around and you may be switching memory cards
between them. If there's an image on any of my memory
cards, I want to see it and know it's there. Until I started using
the All setting, I was regularly formatting cards with forgotten
images on them. From my pain comes a strong
recommendation—use All!
46