Just add blue (a beautifully basic blue button-down, that is). That is legendary photographer Lord Snowdon’s secret to making a great portrait of one of his famed subjects — David Bowie, Serge Gainsbourg and countless others — even greater. These portraits are collected in Snowdon Blue, a book his daughter Frances von Hofmannsthal penned in collaboration with Swedish denim label Acne, which has created a limited edition collection of just these kinds of shirts.