Sony 24-105mm f/4 G OSS Lens Review

bythom sony 24-105mm

Sony has a service advisory for this lens. Lenses with certain serial numbers may not focus correctly when the aperture is closed down, giving the appearance of focus shift. Be sure to check your lens with Sony's 24-105mmm f/4 Service Advisory. The lens used in this test was not subject to this advisory.

What is It?
The Sony 24-105mm f/4 G OSS was a mild surprise when it was introduced in late 2017 along with the A7Rm3. Given that we already had a trio of f/4 lenses and the trio of f/2.8 lenses had been completed, many thought that the next big zoom would be something in the telephoto range. 

But the mid-range is too important to ignore. And a 24-70mm f/4 (the older Zeiss lens introduced with the original A7 series) isn't necessarily competitive when many of the competitors are touting 24-120mm f/4 mid-range lenses. 24-70mm is okay as a compromise when you've got fast f/2.8 going for you, not so much when it comes to an everyday walkabout lens, as 70mm isn't very far into the telephoto range.

That Sony restricted themselves to 105mm at the long end is interesting. I think it shows that they wanted to push performance over flexibility. Designing a 5x lens (24-120mm) that performs really well is a tougher optical problem than at 4x (96mm). That's particularly true when the lens crosses from wide angle optics to telephoto optics. 

So let's talk about those optics. As with most zooms these days, the lens design is complex: 17 elements in 14 groups, with 4 of those elements being aspherical and 3 being low dispersion (ED) glass. The aspherical elements in this lens are fairly involved, with somewhat more unique curvatures than I'm used to seeing. Indeed, Sony claims the frontmost and backmost aspherical elements are "advanced aspherical lenses." They appear to be trying to hold corner attributes both prior to and post entrance pupil. We also get Nano AR coating to combat flare and a Flourine front coat to disperse oil, dirt, and water. 

The lens is compact at 24mm (4.5" or 113mm), but extends almost 2" when zoomed to 105mm. The lens barrel doesn't rotate during zoom, and the zoom ring turns about one quarter of a turn to go from minimum to maximum focal length.

Maximum aperture is a fixed f/4, with the minimum aperture a fixed f/22. A 9-aperture blade opening produces a near circular opening when stopped down.

Closest focus is 15" (0.38m). That produces a fairly respectable 1:3.2 maximum magnification ratio. Not a macro lens, but also not a lens that you have to get back from your subject with, either. To put that in perspective, you can get about a six-inch wide object filling the frame at 105mm at closest focus. There is no distance scale on the lens.

Up front we have a 77mm filter ring and a supplied ALC-SH152 petal lens hood that bayonets into the lens. 

At 23.4 ounces (663g) the 24-105mm can't be considered lightweight, but neither would I consider it a heavy lens. Sony uses the word "lightweight" in their marketing materials, but that's a stretch. The 24-70mm f/4 is a half pound lighter (230g lighter), and with a third generation A7 body and the 24-105mm f/4 you're talking about hanging almost three pounds from your neck strap (1320+g). 

Note that the 24-70mm f/2.8 is 31.3 ounces (886g), so significantly heavier than the 24-105mm f/4. That's sort of the basic appeal of the 24-105mm: more reach, less weight, but you give up a stop of aperture. 

The 24-105mm f/4 G OSS is made in China and retails for US$1300.

Source of the lens reviewed: purchased

Sony's Web site for the lens

How's it Handle?
As with the other FE lenses, there's not much to talk about. The AF/MF and OSS On/Off switch orient to your left hand while shooting and a relatively stiff switches that don't change positions accidentally. The usual Lens function button is right where your left thumb would tend to naturally be when cradling the lens in your left hand. Sony got this right with the first G lenses, and they haven't gone mad trying to finesse control locations or try something different since. That's exactly the way we want our lenses to handle: consistently.

The zoom and focus rings on my sample are what I'd call near perfect. They're smooth but slightly resistant, exactly the way I want them to be.

Overall, the lens handles exactly as I want it to.

How's it Perform?
My expectations for this lens were mixed. The previous Zeiss Sony 24-70mm f/4 was, well, terrible other than maybe in the center. The recent Sony GM lenses such as the 24-70mm f/2.8 have been excellent. Was this new contender in between, or nearer one end of the spectrum than the other?

Focus: Overall, very snappy, even at 105mm with moving subjects. I did see some issues with the lens focusing in very low light (ISO 51,200), but I wasn't really expecting to get good focus performance with an f/4 lens with so little light available. There just weren't a lot of photons hitting the sensor.

IS: Stabilization is controlled solely by the switch on the lens. The body setting is ignored (and grayed out). Sony doesn't seem to make a CIPA claim for the lens, but it appears to perform quite well.

Sharpness: Oh my. I had been shooting with the Sony 12-24mm f/4 and Sony 24-70mm f/4 prior to putting the 24-105mm f/4 on the A7R3 camera. Let me just say this: I immediately knew which images were from the 24-105mm f/4. Immediately. There was a pop and clarity to them that stood out immediately at 24mm. So let's go to the details.

bythom int guatamala December2017 A73 29452-1

Really solid performance across so much of the frame allows you to frame without worrying about corner mush. You might be able to see that the grass in the lower right corner still has integrity (this is from an A7R3).

In the central area, this lens is very sharp right from f/4 at 24mm and at still decently sharp at 105mm, which is unusual for lenses that cross the wide-angle to telephoto territory. At 35mm, 50mm, and 85mm, f/5.6 is clearly a better choice of aperture, though. At no point does the older 24-70mm f/4 even come close to this lens in the center, though. Never. Though I don't trust such statistics generally, Imatest was reporting 20%+ resolution increase from the 24-105mm over the 24-70mm at the center. In this case, visual verification was easy, though: I hooked a mostly uninterested third party into looking at the comparisons, and they picked the 24-105mm from the 24-70mm every time. And that's in the central region.

At the extreme corners, you'll need to get to f/8 or so to get everything this lens can produce. But boy oh boy is that an eye opener. Corners at 24mm f/8 are nearly as good as the excellent center. And so far beyond what the older 24-70mm f/4 produces that there's simply no contest. You will hate your 24-70mm f/4 after seeing what the 24-105mm does at the wide end with a little stopping down. But frankly, even at f/4 the 24-105mm is better in the corners than the 24-70mm ever is at any aperture. 

The superb edge to edge doesn't really stay true as you zoom in, though. At 50mm, the corners are as good wide open as they are at f/8, but clearly less sharp than the central area. The new lens still beats the 24-70mm by a wide margin, though. Generally, at telephoto focal lengths, the 24-105mm is going to go slightly soft in the extreme corners. Call it good in the extreme corners at 85mm and beyond. But there's a plus side: the area which stays sharper is actually fairly wide. Two thirds of the way out I'd call the lenses' performance as very good to excellent at virtually every aperture and focal length. 

And I'd go further: at longer distances the 24-105mm lens does a bit better than at shorter distances. Overall, I'm very pleased with the sharpness of this lens. Corners are no longer totally unusable as they were with the 24-70mm, and there's a great deal of contrast snap to the lens overall, with excellent central sharpness no matter how you use it.

So my question earlier is answered: the 24-105mm f/4 OSS is much closer to the recent GM lenses Sony produced than the earliest FE lenses. Much closer. Enough so that some might find it indistinguishable.

But...there was a discussion on the Internet about focus shift as you stop down with this lens just after it first appeared. Even more strangely, it appears that it was serial number dependent. In AF-S mode, the Sony cameras do their focus work with the aperture wide open (to let in more light). Thus, focus shift would be easily seen, and I've seen several examples of that presented to me by others. Unfortunately, I can't duplicate that on my sample, which seems to have no focus shift at all. Sony now has a recall page open for certain serial numbers of the lens to fix this problem.

In AF-C mode, the Sony cameras use the shooting aperture (because the camera needs to be able to respond immediately if you press the shutter release, with no delay waiting for aperture to stop down). So if your sample does focus shift, one way to avoid it is to use AF-C instead of AF-S. Of course, then we have to talk about the precision of focus for AF-C versus AF-S, which, unfortunately, does not play in AF-C's favor. But a better choice is to just get your sample fixed by Sony. They'll do that for free.

Vignetting: Well, the bad news: even corrected with the profiles you'll see some corner dimming at 24mm f/4. It's actually hard to miss, and it doesn't go away completely as you stop down. Indeed, it's the highest vignetting I've measured on a lens for its intended format. By the time you get to 35mm, the vignetting is much better under control, and can be easily corrected.

Chromatic aberration: Modest levels of lateral chromatic aberration can be see in high contrast images at 24mm, easily correctable. This gets better as you stop down at 24mm. It also gets better as you zoom in, with 70mm being nearly free of visible CA. Longitudinal chromatic aberration is slightly visible at f/4, and seems to go away by stopping down.

Linear distortion: Strong barrel distortion at 24mm of over 4%, and strong pin-cushion distortion at 105mm (at almost exactly 3%). The crossover point between the two types of distortion happens somewhere around 28mm. The camera can correct much of this distortion in JPEGs, and the Adobe profiles also are reasonably good at correcting most of the distortion (both leave about 0.5% non-linearity).

Bokeh: Busy for my taste. A lot of onion-skin and a pronounced—but not colored—edge to out of focus specular highlights. Overall, though, I tended to dislike the focus-to-out-of-focus transition on mid-range object edges: it just looks complicated rather than soft. 

Flare: Sony makes a big deal about Nano coating on this lens. Yes, that helps. But you can still get significant flare with this lens. It's just a fairly predictable and simple flare, though.

bythom US CA Monterey A7III 19805

Final Words
In short, this is the lens you want if you're looking for the best mid-range FE zoom without breaking the bank (or pushing down the scales too far). I can't really think of anything I'm truly unhappy with on this lens, and it's a real step up from the old 24-70mm f/4 ZA. Anyone is going to see that it's a step up, it's that obvious in the pixels. Center, mid-frame, edge, doesn't matter: this new lens just slaps the old one aside.

Of course, the 24-70mm f/4 ZA has one thing going for it: it's smaller and lighter. Almost an inch shorter and a half pound lighter. Indeed, much of the "mirrorless is lighter and smaller" mythology comes from what Sony did with the early A7 bodies and f/4 lenses: they simply made them as small and light as possible, compromising the optical abilities some as they did so. That meant that those early offerings weren't all that competent. The A7Rm3 has bulked up a bit from the original A7R, and the 24-105mm f/4 is definitely a bigger and heavier lens than the 24-70mm f/4. So the size/weight distinction between a highly competent full frame mirrorless system and a highly competent full frame DSLR is not quite so pronounced now. 

Still, an A7Rm3 and 24-105mm f/4 aren't exactly huge. We're talking less than three pounds in a size that can pack into my relatively small ThinkTank Spectral 10 bag with my laptop and all the other basic gear I carry while traveling (headphones, extra batteries, RX-100, chargers and cables, iPad, 

I'm quite pleased with the Sony 24-105mm f/4 G OSS. It's quickly become my primary travel lens of choice for the A7Rm3. And it produces splendidly sharp images with no defects I can't easily manage. Stopped down to f/8 the lens is near spectacular at 24mm, which is where I shoot a lot of the time. 

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