Why Does My Camera Do This?
 

Often, when I am out on a shoot, camera set to raw, when I get home and download my images, the camera has switched to JPEG itself mid-shoot, which is very annoying and inconvenient. Has anyone come across this before and how can I sop it?

My guess is that your camera has a button that switches it from raw to jpg and you are accidentally pressing it. What camera do you use?

canon 60D. It oesn't do it every time and Im not aware of a button that does this

Are you switching settings between the 'Creative Zone' and the 'Basic Zone' on the mode dial? I'm not familiar with the 60D but certainly on my 40D the 'basic zone' only records in jpeg mode.

I think thats the reason why, grrrr, how silly of me. Thanks

This is the issue of creative zone and basic zone. so be aware of this when shooting is on.