Intro

The Sigma 24mm f3.5 DG DN is a compact prime lens designed for full-frame mirrorless cameras and, at the time of testing, available in Sony e and Leica L-mounts. The 24mm f3.5 DG DN was launched in December 2020 alongside a 35mm f2 DG DN and 65mm f2 DG DN as part of Sigma’s new I series, which also includes the existing 45mm f2.8 DG DN. These four lenses are also members of Sigma’s Contemporary series, positioned below the flagship Art range, but still capable of excellent results. What differentiates the I series from other Contemporary models are their compact sizes and some interesting design ideas. In the video below I’ll show you everything you need to know about the Sigma 24mm f3.5 DG DN and how it directly compares against the Sony FE 24mm f2.8 G launched a little later. If you prefer to read the written highlights, keep scrolling!

Let’s start with coverage and to put 24 into perspective here’s the view when shooting with the Sigma 45mm f2.8 DG DN which delivers very natural-looking perspective and magnification.

Now for the Sigma 24mm f3.5 showing how much broader the field of view is from the same position.

And next for the Sony 24mm f2.8 which interestingly is delivering a slightly wider field of view from the same position and on the same camera. Now it’s not uncommon for lenses with the same quoted focal length to capture slightly different fields of view in practice, some due to their construction, others due to software correction later. As I’ll show you later, the Sony 24 2.8 is actually capturing an even wider view in RAW, before cropping it slightly to correct for geometry, but the end result remains a little wider than the Sigma. 

At 64x49mm, the Sigma on the right is a little narrower and longer than the Sony 24 2.8 on the left, and at 225g a little heavier too, but once they’re both mounted on a body you won’t notice much difference in size and weight.

They do have quite different designs and controls though. Despite its compact size, the Sigma 24 3.5 separates its aperture and focusing ring sufficiently to avoid accidental operation of the other, and thanks to knurling on either side of the aperture scale this ring is also wider than the Sony. It lacks the extra controls of the Sony, but less cramped as a result and has an attractive vintage style. The Sigma takes larger 55mm filters.

Meanwhile Sony’s 24 2.8 has a tactile but very narrow aperture ring with a smooth focusing ring positioned right alongside. It’s a little cramped compared to the Sigma, but impressively Sony’s also managed to squeeze in a small customisable focus hold button as well as the chance to declick the aperture ring with a switch, features both missing from the Sigma not to mention most small lenses. The filter thread is smaller too, measuring 49mm.

Both lenses are described as being dust and splash-proof with subtle rubber grommets at their mounts, although Sigma’s sealing doesn’t extend to the whole barrel, whereas Sony’s does.

Both lenses are supplied with quite different hoods. The Sony 24 2.8 on the left comes with a short cylindrical hood while Sigma supplies a more substantial petal hood that obviously occupies more space in a bag, but provides greater protection. I quite like the ribbed styling on the Sigma hoods that ties in with the vintage look of the lens, although it may attract dust over time.

Uniquely Sigma also supplies not one but two different lens caps with its I-series lenses. First is a traditional plastic cap with spring-loaded clips, but second is a metal disc which attaches magnetically, with a satisfying snap and the magnets feel strong enough to keep it in place too. With the hood mounted though, this second cap is a little awkward to fit or remove, so it is arguably a bit of a novelty, but I like that Sigma’s trying something different here.

In terms of focusing in Single AFS on an Alpha 1, the Sigma 24 3.5 is fairly swift and like most Sigma lenses I’ve tested on Sony bodies, employs a minor contrast-based wobble at the end to confirm accurate focus. Sony’s own lenses seem to avoid this wobble in AFS or perhaps do it so fast as to be invisible, but if you switch to AFC continuous AF, the wobble goes away and the process is faster too.

As a demonstration, here’s the Sigma 24 3.5 refocusing for movies where the autofocus is set to continuous and you’ll see the wobble has gone and it looks pretty confident.

For comparison, here’s Sony’s 24 2.8 again for movies where the performance is similar.

Next for a face detection test with the Sigma 24 3.5, again for movies in continuous AF, with Wide area and human eye detection enabled. The 24mm focal length may not be your first choice for portraiture, but if the subject’s positioned carefully it can work for environmental compositions where you see more of the surroundings, plus it’s an ideal focal length for handheld vlogging. Meanwhile the Sony 24 2.8 does an equally good job at keeping me in sharp focus as I move around the frame. Let’s now take a closer look in a stills portrait comparison.

I’m starting with the Sigma 24 3.5 with its aperture wide-open, where it’s possible to achieve a small amount of blurring in the background.

Taking a close look at the Sigma portrait shows very sharp details on my eyeball as driven by the Alpha 1’s eye-detection, and proves the lens has sufficient resolution even for the Alpha 1 sensor. I should mention though the hit rate on focused eyeballs wasn’t quite as high as Sony’s own 24 2.8, so I’d recommend taking several to be sure.

Moving sideways for a look at the rendering shows minor blurring in the background, although for greater subject separation you’ll understandably need faster or longer lenses. That said, for a compact wide lens with a modest 3.5 aperture, the style is quite attractive.

Now back to the full view from the Sigma for a moment, before switching to the Sony 24 2.8 from the same position where again you’ll notice it has a fractionally wider field of view.

Here’s a close look with the Sigma on the left and the Sony on the right where you can see both are capable of capturing very fine details. In my tests I found the Sony lenses delivered close to a 100% hit rate with face and eye detection, whereas the Sigma lenses were a little lower at least when using eye detection on the Alpha 1. That said, I still managed to get plenty of focused portrait switch the Sigmas, just not every single one of them.

Comparing their rendering in the background though tells an interesting story. Looking closely the slightly faster f2.8 aperture on the Sony is indeed delivering slightly larger blurred shapes than the f3.5 of the Sigma, but compare their edges and you’ll see the Sigma’s rendering is smoother with more gradual transitions compared to the sharper edges of Sony’s bokeh blobs. It’s a personal choice, but I prefer the look of the Sigma’s rendering here even though its aperture is a tad slower.

Next for the rendering of bokeh balls from close range, starting with the Sigma 24 3.5 near to its closest focusing distance. From this distance it’s possible to generate small bokeh balls, but like most lenses of this size and price, there’s outlining around their edges and some faint patterns within. With the lens closed to f4 or smaller, the seven-bladed diaphragm system also becomes visible with blobs taking on a seven-sided shape.

Here’s the Sigma 24 3.5 on the left and the Sony 24 2.8 on the right, both at their maximum apertures and from the same distance. As seen on previous comparisons, the Sigma captures a slightly tighter field of view which in turn compensates for the slightly slower aperture to deliver similar-sized blobs in this test. In terms of rendering style, neither lens is free from artefacts, but Sony’s on the right shows visibly sharper outlining versus the smoother edges from the Sigma on the left. There’s no right or wrong here, but I prefer the softer background rendering style of the Sigma.

In terms of minimum focusing distances, Sigma quotes 10.8cm and here’s what I could achieve from as close as I could get – reproducing a subject size of 6.5cm across the frame, albeit quickly becoming soft away from the middle.

Now here’s the Sigma 24 at the top and the Sony 24 at the bottom, both from their closest focusing distances. Sony quotes 24cm with autofocus or 18 in manual, so you’re looking at the latter where it’s reproducing a subject size of just over 17cm, and even with the aperture wide-open the details are pretty sharp right up to the edges. The Sony is noticeably sharper here, but if you can close down the Sigma or shoot from further away, the image will improve.

At the other end of the scale, here’s my distant landscape scene, starting with the Sigma 24 3.5 on the Alpha 1 at f3.5, and with the view angled so that details run right into the corners. 

Zooming-in on the middle section reveals very crisp details at the maximum aperture with no benefit to closing it down to improve the quality further. 

Moving out to the far corner proves the lens can maintain the detail again with the aperture wide-open. There’s unsurprisingly come vignetting, or darkening in the corners, at f3.5, but this reduces as you gradually close the aperture.

Toggling between uncorrected RAW files and the in-camera JPEG versions reveals there’s no geometric corrections applied by default, although applying it from the lens menu of the Alpha 1 did improve some barrel distortion. Compare that to toggling between RAW and JPEG versions shot with the Sony 24 2.8 and you’ll see the JPEGs are benefitting from both geometric correction and compensation for vignetting.

With the Sigma 24 3.5 on the left and the Sony 24 2.8 on the right, showing magnified views of their central areas, you’ll see both perform very well at their respective maximum apertures, although again the Sigma’s view is a little tighter. 

Switching to their corners and again that difference in coverage means we’re looking at different details but from the same part of the frame. Both are a little softer in the corners compared to their central areas and there’s darkening due to vignetting too, but overall their performance for distant subjects is fairly similar here, and once stopped-down, are essentially neck-in-neck.

Just before wrapping-up, a few comments for videographers. 24mm is a nice focal length for handheld vlogging, and you can see here at f3.5 there’s a little subject separation, although if you intend to apply stronger digital stabilisation which incurs a crop, you may begin to find it not wide enough. If you intend to use Active SteadyShot or post-stabilisation in Catalyst, I’d suggest the Sony 20mm f1.8 or the Samyang 18mm f2.8. If you intend to crop a lot, even the Sigma 16mm f1.4 for APSC sensors could be an option.

And finally, a focus breathing test starting with the Sigma 24 3.5 manually focusing from infinity to the closest distance and back again at f22. As you focus closer on the Sigma, the field of view reduces, although at the time I tested on the Alpha 1, I had to perform the full focus pull in several steps. And now for the Sony 24 2.8 which has the opposite effect, so as you focus the lens closer, the field of view increases.