First ask your subject to take a moment to clean around their eye and remove contact lenses – if they wish to wear make-up that’s fine, but a macro lens will exaggerate any clumps or goo, so a clean eye is often better unless their make-up is very tidy, or you fancy fixing it during processing. Place a chair against a wall and ask your subject to sit upright, with the back of their head against the wall – this prevents them from swaying back and forth too much and moving in and out of focus.
2 Let there be light
Presuming you’re using artificial light (either flash or continuous), move your light into position and have a look at the effect that its positioning has on your subject’s eyes. Much like landscape photography, having the light on-axis with the camera flattens detail or texture within the iris, whereas strong side-lighting highlights detail. Pay attention to the catchlight too, and its position within the eye – you don’t want it blocking out too much detail, but at the same time having no catchlight makes the eye look unnatural.
3 Focus carefully
With your light in position, secure your camera on a tripod, attach your macro lens and a remote release and turn on LiveView. Manually set your macro lens to its closest focusing distance and carefully move it into position, looking at the LCD screen to judge when your subject’s eye comes into focus. Once in position, ask your subject to sit very still and carefully fine-tune to focus whilst zoomed into the LiveView preview. You might wish to switch to mirror lock-up mode too, if available, for a sharper image.
If using flash, set your shutter speed to your flash sync speed and adjust the flash power and aperture to give you a good exposure – aim for a mid-aperture of f/8-f/11 for maximum sharpness. If you’re using continuous light then aim to keep your shutter speed above 1/100sec to prevent blur, and increase your ISO, or light power (if available) to maintain a mid-aperture. Ask your subject to look straight ahead, and blink normally to stop their eyes from watering. Get your timing right and fire when their eye is open.