Tamron 17-70 F2.8 Di III-A VC RXD field review

Introduction

The Tamron 17-70 F2.8 Di III-A VC RXD is a very compact general-purpose lens for Sony’s APS-C, E-mount mirrorless cameras. Think of it as roughly equivalent to a 24-105mm F4 lens on a full-frame camera, but scaled down to match the APS-C sensor format.

Although it’s designed for cameras with APS-C sensors, it can still be used with full-frame models when cropped to APS-C. We tried both approaches for this review, pairing it with the Sony a6600 as well as the Sony a7R IV in APS-C crop mode.

With a constant F2.8 maximum aperture across its zoom range, the Tamron 17-70mm makes a great travel lens for photographers on a budget. It also shows potential as a video lens thanks to its vibration control and lack of focus breathing. It’s available now at a price of $799.99 USD.

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Key specifications:

• Focal length: 17-70mm (25.5-105mm full-frame equivalent)
• Aperture range: F2.8
• Stabilization: Yes, Tamron Vibration Compensation
• Filter thread: 67mm
• Close focus: 0.19m (7.5″) wide / 0.39m (15.4″) tele
• Maximum magnification: 0.21x (wide) / 0.19x tele
• Diaphragm blades: 9
• Hood: Included
• Weight: 525 g (1.16 lb)
• Optical construction: 16 elements in 12 groups

With a generous zoom range and good detail out to the corners, the Tamron 17-70mm F2.8 makes a great travel-zoom lens. ISO 100 | 1/30 sec | F8 |34mm equiv.| Sony a7R IV (in APS-C crop mode) Photo by Chris Niccolls

Tamron launched the 17-70mm F2.8 Di III-A VC RXD in late 2020. It’s both the company’s first F2.8 zoom for sub-frame mirrorless cameras, and the industry’s first to achieve a 4.1x zoom ratio, so we were keen to try it in the real world.

For our review, DPReview TV host Chris Niccolls took it on a road trip to the Calgary Zoo and the nearby town of Okotoks, Alberta, while editor Dan Bracaglia gave it a whirl closer to home around DPReview’s headquarters in Seattle.

Let’s take a look at what the Tamron 17-70m F2.8 can do and what it’s like to use.

All sample images edited in Adobe Camera Raw 13 with adjustments limited to white balance, exposure, highlights, shadows, white and black levels. Sharpening and noise reduction at ACR defaults.

Handling

The 17-70mm F2.8 is pretty typical of Tamron’s modern product line. At 524g (18.5oz), it’s very lightweight, but build quality is nevertheless pretty good.

A pair of rings encircle the lens barrel, with the smaller of these near its tapered base controlling manual focus, and the larger one adjusting the focal length. Up front there’s a 67mm filter thread, a size that’s also common on many of the company’s other lenses.

Absent from the lens, though, are any buttons. We found that to be a somewhat perplexing omission; with no dedicated controls for focus mode or vibration control, owners of the Tamron 17-70mm F2.8 will have to spend more time in their camera’s menu system than would otherwise be the case.

The good news is that Tamron’s vibration compensation is generally really solid, and functions well in combination with in-body stabilization if supported by your camera body.

The zoom ring is very smooth and well-balanced. The manual focus ring has relatively little damping and so feels very light in use, but that’s pretty typical of lenses in this category. An internal focusing design means that focus adjustments won’t change the lens barrel’s length or cause filters to rotate, although turning the zoom ring will cause the barrel to extend or retract to match.

Autofocus and manual focus

The Tamron 17-70mm F2.8 foregoes the fancy linear motors typical of higher-end lenses, opting instead for a stepper motor-based autofocus drive. Yet despite that choice, AF performance is nevertheless very impressive, with even significant shifts in focusing distance taking just a fraction of a second on our Sony a7R IV body.

And while this is by no means a macro lens, it can still focus fairly close. At wide-angle, the minimum focusing distance is as little as 19cm (7.5″), yielding a maximum magnification of 0.21x (1:4.8). At telephoto, meanwhile, you can focus to around 39cm (15.4″) for a slightly lower magnification of 0.19x (1:5.2).

The Tamron 17-70mm F2.8’s wide maximum aperture helps portraits pop from their backgrounds. ISO 250 | 1/100 sec | F2.8 |102mm equiv. | Sony a7R IV (in APS-C crop mode) Photo by Chris Niccolls

The good news, though, is that there is almost no focus breathing regardless of focal length. What that means is that the focal length doesn’t noticeably change when focus is adjusted. Along with its quiet autofocus drive, this makes the 17-70mm F2.8 an attractive option for videographers.

Image quality

The Tamron 17-70mm F2.8 pairs nicely with either Sony’s APS-C mirrorless bodies, or with its full-frame models when using the APS-C crop mode. Sony’s APS-C cameras currently top out at 24 Megapixel resolution, while the full-frame a7R IV can extract just a smidgen more detail from its 26.2 Megapixel APS-C crop. We used the latter for our image quality comparison.

ISO 160 | 1/250 sec | F2.8 | 26mm equiv. | Sony a7R IV (in APS-C crop mode) Photo by Chris Niccolls

Sharpness

Near its 17mm wide-angle, the lens is pretty sharp across the entire image frame when shooting wide-open at F2.8. In fact, we didn’t notice much difference in detail levels when stopping down to F5.6, even in the corners.

And the news is almost as good at the 70mm telephoto end, too. Again, sharpness was very good across the frame at F2.8. We did see some improvement to detail when we stopped down to F5.6 this time, even towards the center of the frame, but it was a relatively subtle difference.

ISO 100 | 1/500 sec | F2.8 | 105mm equiv. | Sony A6600 Photo by Dan Bracaglia

Vignetting and distortion

The 17-70mm F2.8 exhibits quite strong distortion throughout its focal length range. At 17mm there’s significant barrel distortion, and as you zoom in, pincushion distortion is readily visible at mid- to tele-photo focal lengths. While distortion is easily fixed in post-processing, the large amount of it present in this lens means it’s likely to impact corner sharpness and, furthermore, will mean a slightly longer corrected minimum focal length on the wide end.

Vignetting is well-controlled throughout the zoom range, with some darkening of the corners which is easily corrected in post-processing.

Although there’s quite strong distortion at wide-angle, it can easily be corrected in post-processing. ISO 100 | 1/1000 sec | F2.8 | 26mm equiv. | Sony A6600 Photo by Dan Bracaglia

Bokeh

There are a couple of weak spots in the Tamron 17-70mm F2.8’s image quality, and unfortunately bokeh is one of them. Amateurs and enthusiasts will likely find it more than acceptable, but users on a quest for maximal image quality may want to spend a bit more for a higher-performing alternative.

The problem, specifically, is quite strong onion ring bokeh. Out-of-focus highlights in images shot with the Tamron appear to be patterned by numerous concentric circles, giving their bokeh an undesirably busy appearance.

The 17-70mm F2.8 is quite prone to onion ring, giving its bokeh a rather busy look. ISO 1600 | 1/250 sec | F2.8 | 105mm equiv. | Sony a7R IV (in APS-C crop mode) Photo by Chris Niccolls

Cat’s eye effect – which causes elliptical rather than round bokeh as you stray further from the center of the frame – is relatively mild, and mostly goes away once you stop down to F4. However, wide open the circle of confusion is increasingly truncated at image peripheries as in the image above. In other words, you may notice chopped-off out-of-focus highlights and generally busier – or sometimes swirly – bokeh as you stray away from the center of the frame.

Flare and sunstars

If you’re a fan of sunstars in your landscape images, the Tamron 17-70mm actually puts up a pretty good showing in this regard, with pretty 18 well-defined ‘spikes’ coming from small, bright light sources in the frame.

In this, an odd landscape photo of a dystopian future where we are ruled by cameras and smartphones (wait, we’re in that world already, aren’t we, and this is just a gear cabinet), you can see that at smaller apertures the Tamron 17-70mm F2.8 produces some pretty solid sunstars. ISO 12800 | 1/20 sec | F16 | Sony a6600

On the other hand, the Tamron 17-70mm is rather prone to flare, which could prove more of a concern. If bright light sources like the sun can be kept out of the frame, though—and the provided compact lens hood certainly helps here—then things aren’t too bad.

Cherry-red flare artifacts can prove problematic if you can’t keep the sun out of the frame. ISO 100 | 1/200 sec | F4 | 77mm equiv. | Sony a7R IV (in APS-C crop mode) Photo by Chris Niccolls

If the sun is in your shot, though, the lens hood can’t help you, and you’ll see rather intrusive cherry-red ghosting, something that can be a pain to fix in post. Again, for Tamron’s target market it’s not likely to be a big issue, but it may push more advanced users up the line to a more-expensive rival.

Lateral and longitudinal chromatic aberration (fringing)

Lateral CA is a type of fringing around high-contrast edges near the edges of the frame; it’s called ‘lateral’ because it appears to the left or right (or top or bottom, depending on the orientation) of these edges. While it’s not attractive, it’s usually easy to remove, and not a particular concern for the Tamron 17-70mm F2.8, largely because with this lens it’s automatically corrected for in JPEGs and in Raw converters.

Longitudinal CA or LoCA can be seen as cyan / magenta fringing in the bokeh circles of this shot. ISO 100 | 1/1000 sec | F2.8 | 105mm equiv. | Sony a7R IV (in APS-C crop mode) Photo by Chris Niccolls

Longitudinal CA, which appears as cyan / magenta fringing just in front of and behind the plane of focus in the Tamron, can be far more troublesome and difficult to remove. It’s not terrible, by any means, but it’s definitely there, and something to be aware of. Note the cyan fringing around highlights around the lettering behind the plane of focus.

Conclusion

Despite a few minor issues that may cause users chasing ultimate image quality to look elsewhere, we think the Tamron 17-70 F2.8 Di III-A VC RXD shines at its $799.99 USD price point. That’s great news, because there really aren’t a lot of alternatives.

ISO 100 | 1/400 sec | F2.8 | 80mm equiv. | Sony A6600 Photo by Dan Bracaglia

If the sometimes-busy bokeh, strong distortion and flare aren’t big concerns for you, and you can live with the slight inconvenience of its lack of physical controls, there’s a lot to recommend this lens. We found ourselves especially surprised both by its corner-to-corner sharpness across the focal range, even when shooting at or near wide-open. And autofocus performance is very impressive, too.

Yet it’s a good 20% cheaper than its nearest rival, Sony’s Zeiss Vario-Tessar T* E 16-70 mm F4 ZA OSS ($999.99), which does not offer unequivocally better image quality. And it’s in a totally different league to the only more-affordable option, the Sony E PZ 16–50 mm F3.5–5.6 OSS ($299.99), a lens which we honestly can’t recommend for anything other than the portability offered by its small size.

And of course, neither of those lenses can match the Tamron’s continuous F2.8 maximum aperture. For that, you’d need to look to the much-pricier Sony E 16–55mm F2.8 G lens. That optic, while excellent, is priced at $1,299.99, and is nearly two-thirds more expensive than the Tamron 17-70mm F2.8, despite offering a narrower zoom range (though some will prefer its wider starting focal length).

Despite some optical flaws, the combination of edge-to-edge sharpness, versatile range, bright aperture and great value is currently hard to find in the APS-C E-mount lineup. If you’re in the market for a new travel zoom for your Sony APS-C camera, the Tamron 17-70mm F2.8 Di III-A VC RXD unquestionably deserves a spot near the top of your shopping list, and easily garners a Silver Award from us here at DPReview.

See what our team at DPReview TV has to say about the Tamron 17-70mm F2.8.