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Tamron 150-500mm f/5-6.7 Di III VC VXD - Review / Test Report - Analysis
Lens Reviews - Sony Alpha (Full Format)
Article Index
Introduction
Analysis
Sample Images & Verdict

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Distortion

The Tamron 150-500mm f/5-6.7 Di III VC VXD does rely on auto-correction with respect to image distortions. In RAW images, it produces a medium level of pincushion distortion in the low- to mid-range. The issue eases a little at 500mm.

With activated image auto-correction, the distortions are perfectly corrected, as you can see below.

Vignetting

The RAW vignetting is slightly higher than average for a super tele zoom lens. At maximum aperture, the light falloff is visible at around 1.5EV (f-stops). However, stopping down by about one f-stop solves this issue by most standards.

With activated image auto-correction, you won't notice a significant vignetting.

MTF (resolution)

Super-tele lenses are difficult beasts and the manufacturers have to live with some compromises in the design - also to keep the price on a sane level. The Tamron 150-500mm f/5-6.7 Di III VC VXD is no different in this respect. At 150mm, the lens is very good to excellent in the image center and the outer image field is still on a good to very good level. There is, however, a caveat here - heavy field curvature, which defocused flat objects in the corners. This is mostly relevant at closer focus distances, less so near "infinity". The field curvature is gone at 250mm and the overall resolution is maintained. At 400mm, there is just a marginal decrease in performance. At 500mm, the center remains very good, although some corner softness is creeping in at this setting.

The centering quality of the tested sample was Okay.

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 CAs (color shadows at the image borders) are quite well controlled, with an average pixel width of around 1px at image borders. Image auto-correction will take care of this, of course.

Bokeh

Super-tele zoom lenses tend to have a rather busy bokeh, specifically with respect to the rendering of out-of-focus highlights. So how does the Tamron 150-500mm f/5-6.7 Di III VC VXD manage in this respect?

The highlight discs (here: at ~300mm) show a relatively busy inner structure and there's also some outlining that is emphasized when stopping down. The more edgy aperture shape starts to show up at f/11. This shows once more that prime lenses still rule the scene here.

The shape of the highlights tends to deteriorate towards the image borders - this is due to mechanical vignetting. However, the rendering is still pretty pleasing, even in the image corners. The highlight discs are ellipsoid here at max aperture. Stopping down "repairs" the corner discs but it requires f/11 for a complete correction (at the expense of ending up with edgy "discs").

The general rendition in the focus transition zones is surprisingly smooth both in the background (shown to the left below) as well as in the foreground (to the right).