I've had my Rebel XSi 450D for about 6 months now. I've been practicing action shots at high school football games, as it has the same setting (field and lighting) as my main volunteer gig. I've volunteered to take pictures for the girls high school soccer team. And yes my daughter is a player on the team. I'm an amateur photographer and have read my owner’s manual several times and have experimented with manual, program, action settings. I've changed the F-number, ISO speed and shutter speed with no success. It's good to know from reading some past treads that even the experienced shooters delete many pictures, because I've definitely deleted my share. I'm not sure if it's my lens or the settings causing the results of the attached photo. Should I purchase an external flash or different lens for action shots at night? Thanks in advance for your time.
The picture is too dark
My picture details below
Lens: Sigma 28-300mm F3.5-6.3 DL Aspherical IF
F-Number (or aperture) 5.6
ISO speed 800
Exposure Time 1/125

