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Canon EF 50mm f/1.8 II (Full Format) - Review / Test Report - Analysis |
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Lens Reviews -
Canon EOS (Full Format)
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Page 2 of 3
Distortion
The lens shows a fairly low degree of ~1.2% barrel distortion on a full format DSLR. This is usually negligible in field conditions.
Vignetting
Typical for most full format lenses it suffers from a rather extreme degree of vignetting (3! EV) when used at its max. aperture setting. Unless you're after this effect you will prefer to compensate this either via a camera setting or post-processing. The situation is much better at f/2.8 but it takes f/4 till the vignetting is no longer visible from a real world perspective.
MTF (resolution & chromatic aberrations)
Classic 50mm primes tend to be rather soft at max. aperture setting but they get extremely sharp when stopped down a bit - the EF 50mm f/1.8 II is no exception to this rule. The center performance is very acceptable at f/1.8 whereas the borders are relatively soft. There's also a lack of contrast at this setting. The quality increases continuously towards medium aperture settings. The lens achieves very good levels around f/4 and the excellent peak is reached at f/5.6. At f/8 there's already the usual (minor) decrease due to diffraction effects.
Please note that the MTF results are not directly comparable across the different systems!
Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness.
If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations
Chromatic Aberrations (CAs)
Lateral Chromatic aberrations (color shadows at harsh contrast transitions) generally very well controlled and not overly field relevant at ~0.6px or less on the average at the image borders.
Bokeh
The quality of the bokeh, the out-of-focus blur, is naturally of major interest for an ultra-large aperture lens like the 50mm f/1.8. Unfortunately it turns out that this is a major weakness of the lens. One major problem is the non-circular aperture shape which is visible in highlights at max. aperture and especially from f/2.8 onwards. The focus blur is pretty even in front of the focus zone but nervous towards the rear.
Bokeh Fringing (Longitudinal Chromatic Aberrations (LoCA))
LoCAs (non-coinciding focal planes of the various colors) are a typical problem of large aperture, non-APO lenses such as the 50mm f/1.8. As you can notice below the halos have different colors - magenta (red + blue) in front the focus point and green beyond. The problem dissolves slowly till it's almost neutralized from f/4 onwards.
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Move the mouse cursor over the f-stop marks below to observe the respective LoCAs
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| f/1.8 |
f/2.2 |
f/2.8 |
f/4 |
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