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Tamron SP 150-600mm f/5-6.3 Di VC USD (Canon EOS) - Review / Test - Analysis |
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Lens Reviews -
Canon EOS (Full Format)
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Distortion
The Tamron lens produces pincushion distortions throughout the zoom range, with a peak of 1.2% at 300mm and a minimum of 0.6% at 450mm. This isn't overly relevant when it comes to nature scenes but it can be noticeable with architecture photography.
Vignetting
There's a moderate degree of vignetting at maximum aperture throughout the range with a peak of about 1.2EV (f-stops). While this is visible for sure, it is not extreme by full format standards. Stopping down to f/8 resolves most of the issue and it's negligible beyond.
MTF (resolution & chromatic aberrations)
Some may be surprised by the relatively moderate performance figures below. Please note that two effects are coming together here. First of all - the "common" peak performance on the EOS 5Ds R, out test camera, is reached around f/4. The Tamron lens is slower than that thus, diffraction effects are already decreasing the resolution potential at all aperture settings. On top of that comes the fact that we are talking about a super tele lens here. Remember that this is a chart-based MTF system and the longer the focal length, the longer the distance between camera and chart. Beyond 300mm air diffusion is starting to have an impact and as you can conclude, it's correspondingly more pronounced the more you zoom out. Please keep that in mind here.
In terms of resolution, the Tamron is a relatively good performer but don't expect miracles from it. We tested it on the EOS 5Ds R thus at 50mp and those 50mp are a stress test for all lenses, really.
The image center is very sharp between 150mm and 450mm even at max. aperture. At 600mm, there's a more pronounced drop at max. aperture. The dead center is still good to very good but the near-center is not so hot anymore. It's worth stopping down to f/8 at this setting, although you shouldn't expect "tack sharp" results in any case. The outer image field is generally rather soft except at 300mm where the lens achieves good results. At 150mm you can boost the corners a bit by stopping down. However, they remain unimpressive towards the long end, especially at 600mm.
The centering quality of the tested sample was relatively good for such a lens. The field curvature is somewhat more pronounced at 150mm but less relevant from 300mm onward.
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 of 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 the image borders) are very well controlled between 150mm and 300mm. Beyond the increase to moderate levels and can get visible in critical scenes.
Bokeh
The max aperture of the Tamron lens may be moderate but a shallow depth-of-field is still easily possible at longer focal lengths and medium focus distances. So let's have a look at the bokeh.
Out-of-focus highlights are pleasing if they are sufficiently "big" but once they compress, they show an onion-like substructure that is getting pronounced the more you stop down. As usual, you'll also have to live with "cat's eyes" at the image borders.
As far as the general out-of-focus blur is concerned - the background is quite smooth (left-hand sample crop below), whereas the less critical foreground blur (to the right) is somewhat harsher.
That being said, you can always push a lens into a situation where it looks bad with respect to its bokeh. Below is a sample crop that shows an out-of-focus image portion with extreme contrasts. Few lenses can compensate for such a situation and neither can the Tamron. However, if the contrast spread remains moderate, the results are pretty good.
Bokeh Fringing / Longitudinal Chromatic Aberrations (LoCA)
The so-called bokeh fringing refers to colored halos in the focus transition zone. Hard contrasts can have a purple color tint in the foreground, changing to greenish beyond the focus point. However, this aspect is mostly an issue for ultra-large aperture lenses and the slow speed Tamron SP 150-600mm f/5-6.3 Di VC USD isn't really affected by this even at max. aperture.
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