I nearly didn't bother with this shot as I'd originally intended this to be shot in colour – the deck chair has blue and white stripes and Marhall had a red shirt – but it didn't work out, mostly because the sea just looked a muddy brown and detracted from the contrasting foreground colours. But in black and white, it's much better.

This shot was converted to B+W using a combination of techniques as follows (particularly aimed at producing contrasty but natural looking skin tones):

First, create a Hue/Saturation adjustment layer and set the saturation to -100. Second, create a Channel Mixer adjustment layer ('above' the Hue/Saturation layer) and convert to monochrome using the Red channel. Next, and this is the interesting bit, alter the opacity of the Hue/Saturation layer until the skin tones look balanced. With 0% opacity the skin tones will be bright (possibly over bright/exposed), with 100% opacity the skin tones may look dull or flat, or underexposed.