Most random stones you’ll find lying around at a campsite will do a little sharpening of a knife but their uneven textures isn’t going to give a good finish and there’s a real danger of damaging the edge of the blade permanently.
If your just doing a single overnight camp its doubtful if you’ll need to take any sort of knife sharpener but its handy to have if there’s a longer camp or open ended backpacking trip involved.
Any half decent knife should manage one night under normal use, i.e light work and not using it to open food cans 🙂
Smiths Consumer Products PP1 Pocket Knife Sharpener
An interesting little tool from Smiths this knife sharpener ticks all the boxes for lightweight camping or backpacking.
With very little weight and versatile enough to cope with different knife styles with the addition of a tapered diamond rod which folds away neatly into the case.
Smith’s SK2 2-Stone Sharpening Kit
As good as some of these tools are, in my opinion there’s still no substitute for spending some time with your knife and a quality wet/dry stone setup.
If you can justify taking a kit camping even though its going to take up more space than something like the PP1 product above, its allows more control over the whole sharpening process.
The Risk Of Overdoing It
Every time a knife is sharpened it takes away some of the metal that makes up the blade. This can be kept to a bare minimum with enough experience, the right tools for the job and only working the blade when necessary.
Unfortunately its very easy to get into the habit of giving the blade a once over the moment it appears a little dull.