Stack for sharpness
Get the ultimate depth of field in your outdoor shots: Rod Lawton shows how to stack a series of frames with different focus points
Don’t risk diffraction from a tiny aperture, try focus stacking instead
If you want the maximum depth of field, or near-to-far sharpness, in your outdoor shots, the usual approach is to set a very small lens aperture. However, while this does increase the zone of sharpness in your pictures, there is a drawback. At apertures of f/16, f/22 or smaller, the image detail starts to soften due to ‘diffraction’ effects.
There’s no way round this. It’s caused by the way light rays bends as they pass through small apertures. In the days of film it was less obvious because the resolving power of film was lower than the digital sensors we use today, and it was harder to magnify images to the levels at which we can view them at on a computer screen. Now, though, the drop in sharpness at small lens apertures is quite obvious. To get the best quality with today’s cameras and lenses, you don’t want to shoot at apertures smaller than f/11 if you can avoid it.
To solve the problem of diffraction, here’s a technique borrowed from the world of macro photography. It’s called ‘focus stacking’, and it means taking a series of shots with the lens
Diffraction is caused by the way light rays bend as they pass through small apertures… To get the best quality with today’s lenses you don’t want to shoot at apertures smaller than f/11
focused at different distances, then combining them in Photoshop.
In macro photography, focus stacking is a painstaking process because the depth of field is very shallow at short focus distances – you may need to take as many as 50 shots to make sure every part of the subject is sharp in at least one of them. But when you’re shooting outdoors, you’re focusing on objects further away. As long as you use a medium aperture of f/8, the depth of field for each shot should overlap enough to leave no ‘focus gaps’ in your final picture.
Our finished picture is made up of just four frames. They’ve been blended using Photoshop’s automatic Photomerge and layer blending tools – there’s really nothing to it.