camera external power supply

well having worried and wondered for a while how I can get 12 converted to 5 with a SMPS I finally realized, whats wrong with a simple external pack of batteries... as 4 X 1.25 = 5 volts. my problem is keep removing the tripod shoes as the camera screw socket is plastic so I'd rather used external power and not have to keep undoing the tripod shoe to get to the battery compartment

When the batteries are freshly charged they'll give 6V which might damage the camera.

yea thats what i am worried about but with 6 V droping to five theres no way of regulating it I don't want to bugger my 300 £ camera

You could use a low dropout regulator. I can't remember what current you require but if I remember it's significant and getting a low dropout regulator for it could be a challenge but it might still be a good idea even if it drops out.

In your original post you mentioned a 12V source. Where does this 12V come from?
The reason I ask is you could stick with the 12V supply, and use a 5V linear regulator to power the camera. It's undoubtedly the simplest solution to the problem, the downside is that it's probably one of the least efficient so whether it's a good solution for you depends on where the 12V comes from.

Brian