Sony 24-70mm f/2.8 GM Lens Review

bythom sony 24-70mm GM

What is It?
The 24-70mm f/2.8 GM is one of three fast zoom lenses for the FE mount (A7 and A9 cameras in the still realm use FE). These f/2.8 optics came late to the scene, with Sony first releasing a trio of f/4 zooms.

So you have a choice: 16-35mm, 24-70mm, and 70-200mm in either high end f/2.8 versions, or in small and trim f/4 versions.

The f/2.8 versions are all G Master (GM), which is Sony's highest designation for a lens. These lenses are designed to perform at the highest levels.

As usual in such lenses, the optical path is complex: 18 elements in 13 groups, with five special elements in the mix, as well as Nano coating. A nine-blade circular aperture diaphragm attempts to retain good bokeh when stopped down. Smallest aperture is f/22. All that glass at a fast aperture means the filter ring up front is 82mm.

Minimum focus distance isn't great at 15" (0.38m), but nor is that terrible. It's about a just-right 1:4.2 maximum magnification ratio. That keeps the lens out of macro territory, but doesn't bury it in "no close work" territory, either.

The lens doesn't have Sony's OSS image stabilization, but I actually see that as a good thing. The A7/A9 camera bodies can easily handle the IS for this focal length range if you need it, and the lack of OSS in the internal design keeps Sony from having to further complicate the optical path. Mid-range zooms are notoriously difficult to make perform across wide angle, normal, and telephoto ranges, and from edge to edge. Sticking IS components into the optical path has a tendency to impact sharpness at the extremes.

This isn't a small and light lens. The overall length is a big 5.4" (136mm), and the weight comes in just below two pounds (886g). There's been a lot of back and forth on the Internet about how the f/2.8 lenses are eradicating Sony's primary asset with their mirrorless products (small size and weight), and this lens is right at the heart of that.

Still, Nikon's latest 24-70mm f/2.8 is 6.1" (154.5mm) long and 37.7 ounces (1070g) in weight. The Sony still has a small advantage, and the overall advantage becomes bigger when you add in the body sizes/weights you'd be using these lenses on.

Personally, I look at thewhole debate a little differently than others. I can put together a camera/lens kit in the Sony FE realm that's very much smaller and lighter than the equivalent DSLR kits, or if I'm maxing out lenses as I would be with the f/2.8 trio, I'm still slightly better off.

There's no DOF scale on the lens, as is generally the case with all Sony lenses these days, and minimal controls. There's one focus fn button (default is focus hold), an AF/MF switch, and a zoom lock switch. There's no tripod collar.

You get a big ALC-SH141 lens hood and a fairly decent soft case for the lens at the US$2200 price.

The lens is made in Japan, and is dust and weather sealed.

Source of the review sample: two-month loan from B&H; thousands of images shot at several sporting events, as well as a few landscape scenics.

Sony's Web page for the lens.

How's it Handle?
The zoom ring on my sample was very stiff, but still smooth. It was also louder during turning than I'd expect for a lens of this caliber, but not obnoxiously so. The zoom lock button is totally unnecessary with this level of resistance to zoom. The fly-by-wire focus ring is the usual Sony Smooth.

The one-on lens function button is a little forward of where I normally hold a lens of this size, but is still in a reasonably proper position to use with your thumb if you're supporting the lens in your palm, as you should be.

On the lighter A7 bodies, this lens will balance a bit front-heavy, but not enough to worry about.

The general feel and build of the lens seems high quality.

How's it Perform?

Sharpness: In the central region at everything except 70mm wide open, this lens is spectacularly sharp. About as sharp as you could ever expect. Even at 70mm wide open I'd rate it at least very good, and maybe excellent; if you stop down to f/4 you get back to spectacularly sharp in the central region.

But oh those outer regions, they tend to trip up the mid-range zooms. I'd rate the extreme corners at only good at the middle focal lengths wide open; at the extreme focal lengths I'd rate it very good. You need to stop down to get everything this lens can deliver, as in f/5.6 or f/8. Even the near center can show significant decline from the absolute central area at 24mm wide open.

Best performing aperture tends to be f/5.6 across the board. Some might quibble a bit on that as f/8 can pull in the corners at some focal lengths a bit more, but the center sharpness is starting to decline as it does.

All that said, the following image taken at a recent Spartan Race is full frame at about 48mm and is revealing:

bythom US CA Squaw Valley Spartan A9 15532

The hay bails from left edge to right edge are very sharp (I'm stopped down three stops). The rendering from obstacle up to the far peak fades from perfectly sharp focus to slight out of focus very nicely, almost like many recent Nikkors.

In looking at thousands of images from that weekend, I find the in-field rendering of the 24-70mm GM better than its test chart rendering, a trait it shares with the Nikkor 24-70mm f/2.8. As noted, the center is very sharp, but with a little judicious stopping down and avoidance of the worst focal length/aperture combinations, this new Sony lens brings home very snappy images. I'd have to put it up near the best of the 24-70mm lenses I've encountered.

Vignetting: As you might expect, wide open the lens has quite a bit of vignetting. About two-and-a-half stops at 24mm f/2.8, with the best case being about one-and-a-half stops at 50mm f/2.8. From 35mm onward, you don't get down to my usual two-thirds of a stop "good" point until f/5.6, and you never get there at 24mm.

The in-camera vignetting correction gets us to "good" for just about everything except 24mm and 70mm wide open, where we still have a full stop of vignetting.

Overall, even with corrections, this lens is a vignetter. This limits its usability for some types of imaging (e.g. architectural). Remember, bringing up corners by as much as you would be with this lens is like shooting at a far higher ISO value, and it's going to introduce noise in the corners you might not want.

Linear Distortion: As is becoming typical, we're seeing zooms with fairly high levels of linear distortion, with the camera (and raw converters) then correcting that if you so wish.

Barrel distortion is about 3% at 24mm, and this turns to about 2% pincushion distortion at 70mm. As is typical with this type of result, the "neutral" point is very close to the wide angle setting, somewhere about 28mm; pincushion is already starting to show at 35mm. The distortion is slightly mustached (irregular), but not enough that you can't apply regular changes and get near perfect results.

Most people will want to turn on the distortion corrections in camera shooting JPEG, or use the appropriate corrections in their raw converter. Otherwise, you won't be getting many straight lines with this lens.

Chromatic Aberration: Not terrible and not exceptional. The wider focal lengths clearly show some higher levels of lateral chromatic aberration that will clearly show up in pixel edges if not corrected on the A7rII. At the telephoto end of the lens, I wouldn't worry about chromatic aberration, even on the 42mp sensor bodies.

Unlike a lot of zooms, there's clear longitudinal chromatic aberration on this lens, which shows up clearly on the edges of bokeh at f/2.8. There's also a bit of onion patterning in the bokeh, but overall I'd call the bokeh good. Not as exceptional as some of the out of focus regions you get from the most recent Nikkors, but much better than what you find on most zoom lenses of this specification.

Final Words
The real question you have to ask at 24-70mm is which of the following two do you value most: (1) corner sharpness, (2) maximum aperture, (3) size/weight, and (4) price. If you haven't guessed, the 24-70mm f/2.8GM is what you buy if you value #1 and #2 over the others. The 24-70mm f/4 Zeiss is what you buy if you value #3 and #4 over the others. Heaven help you if you value #1 and #3, or #2 and #4 the most ;~). Some things aren't possible.

The 24-70mm f/2.8 is easy to recommend as long as you don't mind the size/weight and the price. It's definitely one of Sony's better FE efforts, and it has a nice balance of traits for a fast mid-range zoom.

Despite my comments about corner sharpness, there's not a 24-70mm f/2.8 on the market from anyone that doesn't have some issues with the transition from wide angle optics to normal optics to telephoto optics. Of all the zoom lenses to design, the wide-to-telephoto ones are the toughest to get perfect, as you're juggling so many competing factors.

Sony got this one just about right. It's as "right" as Nikon's 24-70mm f/2.8E, for example, only slightly different (emphasizing center over corners, while Nikon deemphasized center for corners). Said another way, I'd put this Sony 24-70mm up against any other 24-70mm from anyone and by happy. We'd see some slight differences in optical priorities in the results, but only slight.

In short, Sony sought to make a state-of-the-art 24-70mm f/2.8 for the FE mount, and they achieved that. If I were shooting PJ/sports with the A9 every day, this lens would be in my bag, for sure.


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