I recently bought a Canon 5d mark III with the standard kit lens (24-105). I am not a very experienced photographer and so I have been confronted with a steep learning curve but I think I am making reasonable progress.
For most of the photographs, I have been using the P mode with single point spot focus, which seems suitable for what I have been doing. I can still adjust the balance between shutter speed and aperture. The automatic choice seems to lean towards the maximum aperture. Perhaps the algorithm thinks that because I am using spot focus I don't mind having a small depth of field but there are times when I do. It also seems to choose the minimum ISO speed that it thinks it can get away with, which leaves little room to manoeuvre. This seems unnecessary since the ISO speed can be reasonably high before there is any problem with noise.
My question is: How can I adjust the ISO speed to make it higher in these conditions? It is possible to set a minimum ISO speed which would probably do the job but this seems a bit too complicated if I want to vary it from one shot to another. Is there some better strategy which would do everything I need?