What went wrong with this shot D5100 with f/1.8 lens

F5.6 would be iso 800 at 1/30. Or iso 1600 at 1/60. Hardly extreme settings. You honestly think 1.5 ft of dof (if your calculations are correct) would keep everything sharp? And of course you assume the perfect focus plane would be shot, focusing errors happen.

And maybe I'm crazy but the noise at iso 1600 on that camera isn't bad + noise can be fixed, out of focus can't. I'm not sure why so many people on this forum are obsessed with shooting group shots like this at F2. I highly doubt these kids are moving so fast that 1/30 shutter speed would be blurred with VR, esp on a 50mm setting. I've shot this exact same type event using the setting I suggested and the shots came out great, everyone was in focus etc.

I know it's a commonly parroted opinion that fast glass beats a kit lens with VR but the reality is, for many situations like this, it just doesn't. Fast glass is great for subject isolation etc but for group shots where you need DOF, it's not.

--
Stacey