One of the best things about a Cindy Sherman show is you never know what you’re going to get. And in this exhibition, of a new series of "Untitled" images, what you get is very surprising indeed. Sherman's photographs are not about her, but they are always her. Sherman has always used herself – or "herself", a manipulated, redacted representation – as the canvas on which she works. This time, however, the canvas itself has changed.

A well-groomed, middle-aged woman walks into view and lights a cigarette. She stands, she smokes, the camera gives us a steady close-up of her face. As she appears to reminisce, her face subtly registers a range of emotions. Is she agitated, sad, irritated? She takes long drags of her cigarette. The film ends and she walks out of view. A second film begins. Same woman, same duration. A cigarette is smoked, the camera lingers on her face. She’s lost in recollection, but wait, there are subtle changes. A different backdrop.

In National Anthem, the debut play by bestselling novelist Colin Bateman, a composer lies prostrate on the floor. Half hungover, half waiting for inspiration, he has been commissioned to co-write an anthem for Northern Ireland with a poet and has a day to do it before flying back to his continental tax haven. The ad-hoc alliance soon fractures as differences emerge. One is Catholic, passionate and pretentious, one has sold his Protestant soul to MOR rock and platinum sales. Can the two sides work in harmony?

Camera-less photography isn’t, as some might think, a 20th-century invention, discovered by experimental Modernists such as Moholy-Nagy and Man Ray. Thomas Wedgwood, before the invention of the camera and at the very beginning of the 19th century, made paintings on glass and placed these in contact with pieces of paper and leather which had been rendered light sensitive with chemical treatments. Where the painted areas blocked the light, the image left its trace. Unfortunately, since Wedgwood lacked knowledge of how to fix the images, the results vanished almost as soon as they appeared.

With the Frieze Art Fair now upon us, the only sane response for anyone interested in art is to leave London until the wretched event is over. Art fairs are for art what pimps are for virgins, to misquote Barnett Newman. The work, in other words, doesn’t stand a chance. And just as supermarkets don’t give shelf space to products for you to admire the packaging, art fairs don’t display work for you to look at and enjoy. In each case, the point is to purchase.

While most will be familiar with him as an actor, and some will know him also as a photographer and painter, few will be aware of the full extent of the late Dennis Hopper’s artistic practice. Hopper, who died in May of this year, did everything from taking photographs of Dr Martin Luther King Jr during the historic Selma-Montgomery marches through producing oil paintings inspired by the scale of billboards to making pop-art assemblages, abstracts, and painting large-scale figures appropriated from commercial advertising.

One of the most difficult questions to answer is what makes a great performer great? So much that happens on stage takes place in an eye-blink. Dancer A is "better" than Dancer B, but why? Critics talk about "line", about "extension", about how dancers use and shape space. But it is hard to see shapes in words. Now portrait photographer and installation artist David Michalek has, with one deft blow, solved this problem.

It takes a lot of work to make a show look as unconsidered and chaotic as this one: thought and care and time and attention all have to be paid before something so random can be achieved. But as so often with Tillmans, the nagging questions persist: is randomness, are the offhand and the casual, valid as ends in themselves? Because Tillman’s über-hip affectless cool has become very tiresome indeed. Even worse, it’s becoming predictable and dull. Tillman's eye, as ever, remains wonderful, but I remain doubtful about the form in which he chooses to convey his ideas.

Many people use that weaselly phrase about Antony Gormley, saying he “divides the critics”. For the most part this is not true: for the most part the critics loathe Gormley’s work. They suggest he is either a bad figurative sculptor masquerading as a conceptual artist, or a bad conceptual artist masquerading as a figurative sculptor. This is really just a whinge that he doesn’t fit in a box, but so what?