Sony 500mm f/4 G SSM review: The longest super telephoto prime lens ever tested by DxOMark

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DxOMark Lens

Introduction

Sony announced the SAL500F40G at Japan’s premier imaging show CP+, staged in Yokohama in early 2012, though a prototype was premièred at CES in Las Vegas in 2011, alongside mock-ups of the to-be-released SLT-A77 and A33 models.

Made to order, the $13,000 500mm f/4.0 model is the longest focal length lens from Sony bearing the G-series moniker, once an indicator of premium quality lens designs from Minolta that Sony acquired back in 2006.

The optical construction is a modern design with no less than three ED glass elements plus internal focusing (for quick focusing and minimal disruption to the centre-of-gravity). It also features an ultra-sonic type SSM that’s also compatible with the on-chip phase-detection AF mode of the top-flight SLT-A99 and Nano AR coating (a sub-wavelength type coating optimized for digital capture, reducing ghosting and flare).

To help lessen weight to relatively reasonable levels (it weighs in at 7 lbs 10 oz, or 3460g) the lens features a magnesium alloy body and it’s both dust and moisture sealed.

Sharp-eyed readers may note that the lens doesn’t feature image stabilization, but that’s due to Sony SLT cameras adopting a stabilized sensor. On APS-C SLT type camera the lens is the equivalent to a 750mm f/4 (on a 35mm full-frame,), however, if combined with one of the Sony NEX models using the $400 LA-EA2 adaptor the combination doesn’t benefit from being stabilized.

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Thanks to our new Seattle Lab, we’re now able to evaluate super-telephoto lenses and the SAL50040G is the first of those, with the results of more to be delivered over the coming months.

Sony 500mm F4 G SSM mounted on Sony Alpha 900

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Measured on a 24Mpix Sony Alpha 900, the 500mm f4 G has a DxOMark score of 20, slightly lower than we might have anticipated in a high-grade lens like this. If you look at the Metric scores individually, the Sharpness score is a slightly disappointing 16P-Mpix, 30-percent below the 24P-Mpix potential maximum that could be achieved on the Alpha 900. But that’s a collective function of the camera sensor and lens, and a more efficient sensor may have produced a higher result.

Of course what matters on a lens like this, especially as one as pricey as this, is the performance at maximum aperture. While sharpness is a bit on the low side, it is extraordinarily homogenous across the imaging field at f/4; you won’t notice any difference in images at 100-percent on screen or in prints viewed up-close. In fact, the difference is less than 1% measured from the centre to the corners and an excellent result.

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At maximum aperture, the Sony 500mm has homogenous sharpness across the imaging field

Slight pincushion distortion can be measured but it’s not noticeable in real world use, and neither vignetting nor chromatic aberration are likely to be problematic and well within expected tolerances.

The transmission score, measured at 4.3Tstops (on the Sony Alpha 900) is a little lower than expected and disappointing given the lower number of elements (11 elements in 10 groups) used. Both the Nikon and Canon lenses feature optical image stabilization and have a higher quantity of glass elements in their construction, 16 in 12 groups in the case of the Canon.

Sony 500mm F4 G SSM mounted on A900 Vs Canon EF 300mm f/2.8L IS II USM Vs Canon EF 300mm f/4L IS USM both mounted on 5D Mark II

Thanks to the new facilities in Seattle the Sony is the first super-telephoto 500mm that we’ve been able to test. However, we have recently assessed the Canon 300mm f/2.8L IS II USM, the first in the series of up-graded telephotos lens from the firm eschewing UD (ultra low-dispersion) glass and adopting a double fluorite element design instead.

With that in mind and no direct comparison for us to work with, the Canon 300mm f/2.8 is almost certainly out-resolving our test camera the Canon EOS 5D Mk II, scoring the maximum possible 21P-MPix in the sharpness test, and, seemingly, out-resolving the Sony 500mm. Also bear in mind the Sony Alpha 850/900 models adopt a sensor with a higher pixel count than the Canon.

In other respects, the Canon performs similarly, including a somewhat poor Transmission value, though the lack of distortion is notable, as is the very low chromatic aberration. The older 300mm f/4 IS USM is showing its age, with a low 13P-Mpix Sharpness score and disappointing Transmission value (of 4.6Tstops). Chromatic aberration, Distortion and Vignetting are close to the longer, more difficult to correct 500mm f/4G, all pointing towards the Sony performing well in these areas.

Overall, the Sony looks promising but it’s a pricey option. As well as using fluorite the new Canon super-telephotos have the latest image stabilization technology (offering up four-stops compensation, and including a new Mode 3 option to prevent disruption during composition). Not that, that is going to be of interest to Sony users, but goes some way to explain the cost of a lens like this. Without those features or the performance to match, the Sony lens looks over-priced.

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Although the Sony is consistent across the field it can’t match the sharpness of the shorter, yet faster 300mm f/2.8.

Based on our P-MPix figures, the Sony is close to 20% sharper than the Canon 300mm f/4L IS USM, but some 20% less sharp than the new Canon 300mm f/2.8 L IS II USM. It’s worth noting that although the Canon lenses are shorter in focal length and easier to correct, the additional stop in ‘brightness’ or Transmission (actually 1.1TStops) of the 300mm f/2.8 makes that and the Sony similarly challenging to correct for aberrations during the design stage.

You could look at it another way. Teleconverters are regularly used to supplement telephotos, and while the 300mm f/2.8 matched with a 1.4x converter may be too short at 420mm f4, a 2x extender will give you a 600mm f/5.6.  Both types are made for Nikon lenses but they also produce a 1.7x teleconverter that will adapt the AF-S 300mm f/2.8 to a 510mm f/4. If you’re more likely to find use of a 300mm and require longer lengths less frequently, supplementing that with teleconverters may be answer.

Given the price, some 27% higher than the equivalent Canon EF 500mmL f/4L IS II USM that now shuns UD (ED) glass in favor of Fluorite and includes an optical stabilized system, there’s no doubt the Sony is an expensive choice. Nevertheless, it is a welcomed addition to the range. Even if at first sight it appears that sharpness is not one of its strong points, it’s at an acceptable level for the current Sony full-frame cameras. As for chromatic aberration, distortion and vignetting, these image-degrading properties are handled quite well, but the 4.3Tstop transmission is disappointing. We’ve not yet had the opportunity to test rival offerings for direct comparison, so the alternatives may not actually perform any better, or be any more suited to higher resolution sensors. At around $4,999, Sigma makes a 500mm f/4.5 EX DG – it lacks, however, the fast-focusing HSM option that is present in the Sony mount. Alternatively, the recently upgraded $7,500 Sony 300mm f/2.8 G SSM II may be an option with teleconverters; Sony users are however somewhat limited in choice, as the 500mm f4G SSM is the only super-telephoto currently available to them.