Really thanks, that is a clear answer. I will check the manuals you gave me. What I thought (ignorant) was that my camera takes ALL the firmware from CHDK so it is like a new camera totally depending from CHDK firmware. But you are telling me that the behaviour is another, the camera becomes only able to accept scripts so if I give her a whatever script in the <ALT> mode (for example T=60" and ISO=400) the camera plays the script and all the other variables remains the same like in a normal functioning situation... that's great so CHDK is an add-on for the camera, it is not all the firmware... but tell me, is there any dangerous situation for the lens of my camera? For example, to be honest, the situation T=4minutes and ISO= 3200 (extreme situation I know but anybody can do for joke after 3-4 beers) is a danger for my lenses or not? THANKS for your kindly response and for your time