Hi Kate,
Given the choice between a technically perfect average moment or a technically average perfect moment I will go for the latter – every time. Almost anyone can create a technically perfect image – but great moments are a lot more difficult to capture.
This image here is a case in point. The moment is great, the guitarist has his hair flying in the air along with a great pose and a reasonable pout on his face to match the music. When combined with the stage lighting I would say this image has a lot of energy and that is a good thing.
From a technical perspective though, this image is just a hint on the soft side. There are probably a couple of reasons for this – one is the fact that this guy was likely moving about on stage in an unpredictable fashion. My guess is that between the camera focusing and the actually capture being made this muso shifted out of focus.
As another consideration, I notice that you made the image at your lens' widest aperture – f/1.8 – and that really does give you a narrow depth-of-field, particularly if you are this close to the subject.
Rather than working at f/1.8 at 1/125s of a second at 800 ISO, I would be inclined to bump the ISO up one stop to 1600 ISO and then close the aperture down closer to f/2.8. This will help make the image look that little bit sharper.
The one thing I would do then is to clone out the two small lights on very left edge of the frame and I think you are in business.
Keep up the good work!
Cheers,
Anthony