10 things we learned in this test
If you haven’t used a really fast lens before, there are some important factors that soon come to light
1 Be sharp
The widest available aperture of f/1.4 really can give an incredibly shallow depth of field to your shots, so accurate focusing is critical.
2 The eyes have it
Given the need to blur fussy backgrounds in portraiture, fast lenses are ideal. At f/1.4, it’s more important than ever to focus precisely on the eyes.
Using the widest aperture in portraiture, it’s likely that areas of the face and hair will be defocused when you’ve focused on the eyes. This can be useful for softening complexion, and smoothing out wrinkles.
4 ND filters
When you want a tight depth of field but the light is too bright to enable use of a very wide aperture, fit an ND (Neutral Density) filter to the lens.
5 DOF preview
When narrowing the aperture from its widest setting, the DOF Preview button can show the resulting depth of field. However, the viewfinder image will be darkened, so it may be preferable to use Live View mode for focusing.
6 On the fringe
Unlike the more usual sort of fringing (lateral chromatic aberrations), coloured halo effects caused by ‘bokeh fringing’ (longitudinal chromatic aberrations) can’t be automatically corrected in camera, and need fixing later.
7 Speed thrills
If you don’t need a large depth of field, the wide apertures offered by these lenses enable handheld twilight shots without the need to push ISO settings to very high values.
8 Live View focusing
Contrast-detection Live View autofocus tends to be more accurate than the regular phase-detection autofocus mode, as it works directly from the camera’s image sensor. However, it’s also much slower.
9 Move closer
With 35mm lenses in particular (compared with 50mm and 85mm lenses), you’ll need to move closer to the main subject if you want to blur the background effectively.
10 See clearly
It’s easier than usual to focus manually with fast prime lenses, because the viewfinder image is much brighter thanks to the extra wide aperture.