P mode picks a setting for shutter speed and aperature when you
press the shutter release half way. You can tehn "program shift"
the settings with the control dial if you don't like what it chose.
Say you are shooting P mode and you press the shutter release half
way, in the viewfinder you will see the speed and aperature taht
has been chosen to give "proper" exposure. Now, say it has chosen a
wider aperature than you want, becuase you want the Dof to be small
in this shot. Just rotate the dial and wht in the view finder - it
will adjsut both the shutter speed and aperature - up or down
depending on which way you trun the dial.
If at the same time you want to dial in some EV compensation, just
use the thumb dial on the back of the camera.
The end result is the same as if you had used AV or TV (or even M)
mode - assuming you trust the exposure reading/setting from the
camera. The differnce is instead of setting one of them manually
and etting the camera set the other, you are in effect setting both
at the same time.
Frank
I prefer to use "M" when I can so I know what is going to happen,
but if the light is variable I will often change to "Av" so I can
control the aperture and let the shutter speed be whatever it has
to be. More rarely, I will choose Tv.
I guess I just don't know what the camera will pick in "P" mode (I
know there is a table some place). Maybe I am just more of a
control freak

)
I have a 1D, a couple of L zooms and a couple fast short primes
that I bought to help shoot my kids sports. I love it all so far.
However when I am traveling, hiking, or just shooting the family in
the yard kind of stuff, I find myself relying on the P mode.
The family is always moving around, nothing is ever set up or posed.
I will use AE lock or Program shift sometimes for some more control.
The 1D does such a great job at metering that P works great almost
all the time. Compared to the spikey histograms I was almost always
getting with my E-10, the histograms on my 1D images are nice,
smooth curves.
So...What is so bad about shooting in P mode?
--
I plan on living forever - so far so good!