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

apaflo wrote:

Welcome to the world of Event Photography... where you'll very commonly shoot in poorly illuminated auditoriums and gymnasiums. And you'll learn a few tricks!

As others have mentioned, you used Auto Exposure, probably ADL though the Exif data doesn't say so one way or the other, and spot metering. The specific problem of course is that the "spot" was on a fairly dark area right in the center of the image, so it brightened the whole image.

Next time you'll want to do it a little differently. Use Manual Exposure mode. Use a higher ISO too, to allow both a higher shutter speed (say about 1/100) and also allow you to stop the lens down a bit too. That shot was at ISO 320, 1/60 and f/2. You might want to try ISO 1600, 1/125 and then stop down to say f/4. That would give you a lot more Depth of Field, would freeze any movement much better, and would reduce exposure by about 2/3 of a stop (which may not be enough, and if so you might try ISO 800 or something in between).

The Light Value from the Exif data says 6.2 EV, which isn't really bad for this kind of thing. Some are 1 EV higher, but some are 2 EV lower too!

Eventually you'll also decide that a 50mm lens doesn't provide enough functionality. You'll want to look at a 70-200mm f/2.8 VR. Not cheap, but note that that is not the newest version with VRII. The older version will be just fine on a DX sensor body like the D5100.