GLOC(Offline)

As I understand it, backup lights need to have 3 C-cells to be considered DIR but something like the Lenser Frogman which is powered by 4 x AA is not DIR (or so I believe). Why?

I understand the rational that for a backup light you need to have good battery life hence the 3 C-cells, but if the Lenser has 50h battery life with 4 x AA cells, surely this is longer than 3 C-cells on a tungsten bulb (5.5-6 hours quoted). The Lenser is measured as 1.25W & 33 Lumens, whereas the Scout and Photon Torpedo are both 5.5W but I have not been able to find the lumens (the important number) and so a direct comparison cannot be made as the shape of the reflector has a lot to do with the final light output.

So, what is the 'real' definition of a backup light, is it based on brightness, battery life, or some other thinking?

Thanks

Gareth