The Half captures the moments just before an actor goes on-stage – the half hour in which they "become" the character they are about to play, and normally a very private time that few get to see. Luckily, renowned theatre photographer Simon Annand has been allowed to take pictures of actors at this very personal time, the best of which are being exhibited at Idea Generation Gallery. These rare shots offer an extremely candid look at some very famous performers at their most vulnerable: so often seen poised and posed, here their immediacy and honesty is instantly striking.

"The half" is a theatre term with almost mythical connotations that refers to the private time devoted to an actor's craft, and the merging of two personalities into one body before the rigors of performance. What's hugely pleasant about this exhibition, is that it blasts some of the more mystical aspects of this to one side – there are plenty of photos of pensive actors staring off into the middle distance, but far more show the personality and individuality that radiates from such talented performers and sets them apart from the throngs of less successful actors. Emotions run the gamut from nervous to excited, and the sense of enjoyment that a lot of these talented people get from their craft is instantly apparent.

Not that the more sombre photos have less impact – the quiet dignity and gravity of an intensely concentrated person is quite riveting, and there is a sense that some of these performers do fully open themselves up to sharing their personality with a fictional character. The beauty of acting has always been that there are a million and one ways to rehearse and perform, and it's nice to see so many different styles juxtaposed – there is no sense of hierarchy or judgment of who is doing a better job in preparing. It's a quiet insight into an industry that likes to shroud itself in mystique, and that's part of the fun here.

The photos are also very graciously candid – there's no sense that these shots have been deliberately posed, and each manages to capture something about the actor that most other photographers have had trouble capturing. This is likely because they are taken at a time when actors are so particularly receptive, open and focused. And because they are in a dressing room, there is something very visceral about the closeness of these pictures, both physically as well as emotionally.

It's particularly strange to consider these photographs alongside other pictures that we have of these performers. For example, Daniel Radcliffe's face couldn't be more well-known from his countless films, posters, and press shots -- yet in his photograph here, he is almost unrecognisable. He has more character in Annand's portrait than I've ever seen in him before – and maybe capturing him at his most vulnerable is what makes that possible. All of these photos are delightful and insightful, and I'd thoroughly recommend a visit.

Simon Annand: The Half, at Idea GenerationChris Hislop reviews Simon Annand: The Half at Idea Generation Gallery.4