WCXX

In such circumstances, it's easy to forget that Ruskin was perhaps the nation's finest ever art critic: champion of both Turner and the Pre-Raphaelites. He also dabbled as an artist himself, as a charming new exhibition of drawings and photographs reminds us.

Ruskin demanded artists forsake beauty for truth. Their practice should involve "rejecting nothing, selecting nothing and scorning nothing, believing all things to be right and good". His meticulous scrutiny of nature's detail rather mirrored Darwin's.

The invention of daguerreotype photo-graphy in 1839 proved a revelation. Ruskin was an instant devotee, revelling in these images – of previously unimaginable accuracy – on polished silver plates. In its early years, the daguerreotype was mainly used for family portraits, but Ruskin had other ideas. During the course of various trips, he took – or had taken by his trusty manservants – hundreds of photos of European hotspots.

Venice was his favourite, and Ruskin seems overwhelmed at the fact that, on returning home, he no longer had to rely on drawings or memories of the Doge's Palace. With photography, it was "like carrying off the palace itself", he said. "Every chip and stone and stain is there."

It's fun to see a man of such earnest erudition showing his childlike side. In his vertiginous picture of Palazzo Bernardo, taken from a gondola, we see him playing with perspective – like a boy with his new toy. He wasn't averse to climbing awkward heights for a decent shot, either – witness his close-up of the Smiling Angel at Reims Cathedral. Indeed, so intrepid was he, Ruskin thought nothing of lugging his daguerreotype equipment up the Alps and taking the first known photo of the Matterhorn.

The chief purpose of these images was to illustrate his books (such as The Stones of Venice), as well as aid their writing.

Ruskin was also a keen draughtsman and he continued to draw even after discovering photography: a medium that rendered his sketches obsolete in terms of truthful record. Several are on show here, and I suppose there's some interest in the way photography (consciously or not) started to influence his drawings – for instance, the heightened shadow effects in San Martino cathedral, Lucca.

But, for me, it's the photos that stand out. They mark a blissful union of Ruskin's aesthetic and scientific interests: like the happy marriage he himself never had.

'John Ruskin: Photographer & Draughtsman', at Watts Gallery, Compton, Surrey, to Jun 1; wattsgallery.org.uk 01483 810 235

READ: The unfinished story of John Ruskin