Lucas Cranach: Repeat to fade

Lucas Cranach's art could have a dark and compelling force. If only he hadn't kept on doing the same thing, says Tom Lubbock

A stylish artist is Lucas Cranach. Whether he's much more than that, I doubt, but his work is worth exploring. This German Renaissance master is slightly peripheral to the vision of the average British art-goer. The name calls up images of slinky, boneless, trainer-bra nudes wearing big hats, or hard-lined mug shots of the Protestant reformers. Cranach at the Royal Academy is the artist's first major appearance in this country, and it has about 70 works. He and his busy studio specialised widely – in portraits, light pornography, low comedy, Lutheran (and sometimes Catholic) propaganda, courtly celebration, devotional images, mythological fantasies.

I wouldn't call the show a big revelation. Make the most of it, though. This is the only solo Old Master show we're getting in Britain this year – or (not to forget Pompeo Batoni at the National Gallery) the only serious one. It's hardly comprehensive, either. It travels from a previous, much larger showing in Frankfurt. And if you leaf through the catalogue, you'll find that all too many of the more interesting-looking images – Martin Luther on his Deathbed, say – come with a little phrase in brackets on the page opposite: (Frankfurt only).

The show is still enjoyable, of course it is. Cranach-world is full of nice, neat sensations. It's a fiddly, bitty, picky universe, of clipped edges and wiry lines, cracks and creases, crisp folds, crunchy foliage, elaborately decorated fabric. Wine-gum colours gleam out from dark backgrounds in gem-like segments. Fine-combed beards, tight-knotted braids, studded bodices and the links of ornamental chains broadcast a plethora of metallic glints.

Cranach is one of those artists who offer us a sense of molecular clarity, of things being clear deep down into the grain and minutiae of them. It makes the world itself feel like a work of craftsmanship, something wholly within our grasp. Sometimes, among this dense visual texturing, bright slips of flesh appear. In contrast to the surrounding bittiness, Cranach's smooth nudes feel properly bare. Whether the pretext is the Garden of Eden or Greek mythology, these images are clearly interested in a feeling of nakedness, and presumably their first customers had an appetite for the Cranach body. But I think it's normal nowadays to feel a bit queasy about his figures.

It comes from the way their outlines are as sharp as paper, but the flesh inside them is as formless as beaten egg. Like soft cake-mix in hard cookie-cutters, these bodies offer no resistance to the weird, sinuous shapes that Cranach imposes on them. With snake-like torsos and frog-like limbs, his Venus and Lucretia pose against darkness, while standing on a shallow curved foreground. People who like to set the flesh-loving Old Masters against the flesh-denying ways of the fashion industry should remember their Cranach. You won't find a stranger or more artificial body-ideal on any modern catwalk.

So Cranach can make your eyes light up, and your skin crawl. But he can't touch you, because he isn't himself fully in touch with reality. His art may have a look of truthfulness. After all, Cranach-world isn't just bitty. It's spiky, wonky, wiggly. It has qualities that give the impression that something definite and resistant is being registered. And this makes it fit in with a broad artistic stereotype. Ah yes, the northern renaissance. The northern artists don't idealise and classicise like the Italians. They know the cold and the wind, the dark forest, the dark Protestant mind. They have a sense of hard, ugly, awkward reality.

But if this generalisation ever has any purchase, it doesn't apply to Cranach. He shows that you can make a spiky, wonky, wiggly world, and still lack any feeling for the facts. Spikiness can be just another form of idealisation, another mode of slickness. Think of Bruegel, with his feeling for the weight and strain of bodies, their active clumsiness and hard-won grace. Cranach's bodies simply don't work, they don't even try to: they're nothing but pictures of bodies. Or think of Dürer, with his sense of the particularity of things. Even when he is making up fantasy creatures, he understands the unpredictable ways in which the world takes shape, how it always exceeds artistic invention.

Recalling the work of those two near contemporaries, you appreciate the amazing idleness of Cranach's picture-making. He deals entirely in formulae. He has at his disposal a bank of visual clichés for doing hair, hands, trees, bodies, babies, which he uses as applicable. Most of the time he is simply not bothering.

Cranach fills great swathes of his pictures without any thought at all. How much of the surface area of his work is accounted for by the mere repetition of forms! The multiple sleeve-slashes of a fashionable tunic, the straight pleats of a skirt, the scrolls of a beard, sprigs of leaves, tufts of grass, apples in an apple tree, stones on stony ground – one after another after another, and the ground is covered.

Now, it would be stupid to imply that visual repetition is always bad. It is beautiful when Botticelli repeats the twinkling V-shaped waves of the sea in The Birth of Venus. It is beautiful when he repeats the flowers and vegetation of the meadow floor in The Primavera. He's trying to make us feel that nature is like a piece of human decorative patterning. The idealisation is conscious and to be understood as such.

Likewise, it's fearsome when Albrecht Altdorfer – one of Cranach's immediate heirs – repeats hundreds of helmeted heads and hundreds of lances in his epic The Battle of Alexander at Issus. The unending repetition of armed men, the sheer mind-boggling quantity of them, the indifference of one man to another, is part of his sublime and terrible scheme. But Cranach repeats to no such purpose. The meadow floor in his mythological nudist colony, The Golden Age, isn't thinking about pattern and artifice. It isn't thinking about anything. It's just saving time and filling space.

The way that Cranach goes wrong is a way that art often goes wrong, and often gets liked for it, too. It finds a trick for doing the world and gets stuck on it. The trick is nice enough. And in a way the stuckness is nice, too: it's regular, it's undemanding, it's reliable, it's soothing. There are times when you like things to be on autopilot.

But then you remember what else art can do – Dürer's, Breugel's, Altdorfer's, Botticelli's – and how every inch of a picture can demand and reward your attention. Cranach is not just lazy, he simply can't help himself. He can't get himself off autopilot, even when a little improvisation would have made all the difference.

Christ Blessing the Children has Jesus thronged by mothers presenting their babies. Heads overlap. Eyes peep out of narrow gaps. A pressure of eager intimacy builds up. And then you notice that every single baby's head is the same baby's head, from the studio "baby's head" template book. If he won't bother, why should we?

Cranach, Royal Academy, London W1 (0870 848 8484), to 8 June