The Sigma 23mm f1.4 DC DN is a mild wide angle lens designed for mirrorless cameras with cropped APSC sensors. Launched in April 2023 and initially available in Sony-e, Leica-L and Fujifilm-X mounts, it delivers coverage equivalent to 35mm, ideal for general-purpose use. Before you ask, there’s no plans for Micro Four Thirds, Canon or Nikon versions, at least not yet.
The 23 becomes Sigma’s fourth DC DN prime lens designed for APSC sensors, joining the existing 16, 30 and 56mm models, all sporting bright f1.4 apertures. Placed side-by-side you’ll see all four share a family resemblance, with similar design and controls.
If you’re a Fujifilm owner, you already have the choice of two XF 23mm lenses, the compact f2 which is a little cheaper than the new Sigma and the high-end f1.4 which is pricier at around $900. The model I want to place it side-by-side with in this review though is Sony’s 24mm f1.8 ZA, a collaboration with Zeiss launched over a decade ago in 2011 when Sony still used the NEX-branding for APSC mirrorless. I use this lens on my A6400 to film most of my YouTube videos and it still sells for around $800. In my full review below, you’ll see how the new Sigma measures-up, but if you prefer to read the written highlights, keep scrolling!
Sigma 23mm f1.4 DC DN: 66x79mm, 330g // Sony 24mm f1.8 ZA: 63x66mm, 225g. They’re similar in diameter, but the Sony is 13mm shorter and roughly two thirds the weight thanks in part to its slightly dimmer aperture.
Like other models in the series, the only control on the Sigma 23 is a smooth and well-damped manual focusing ring. Likewise for the Sony lens, neither of which has any switches mounted on their barrels.
Like most new Sigma lenses, the 23 1.4 has a rubber grommet to provide sealing at the mount, albeit not throughout the rest of the barrel. Conversely the Sony 24 1.8 doesn’t appear to be sealed at the mount, so use with caution.
At the other end of the lens, the Sigma employs a 52mm filter thread and is supplied with a bayonet lens hood. The slightly narrower barrel of the Sony takes 49mm filters, and the lens is also supplied with a hood.
Ok, now for focusing, and unless otherwise stated, all my tests were made using a Sony A6400 body. Let’s start with the Sigma 23 wide-open to f1.4 and using single AF mode to pull-focus between the two bottles. There’s the usual wobble at each end to confirm the focus, but it’s quick enough for general use. Switch the camera to Continuous AFC mode though, and like most Sigma lenses I’ve tested, the focusing speeds-up and avoids the confirmation wobble for faster overall response.
Now let’s compare the Sony 24 at f1.8 where it looks a little faster overall in Single AFS mode, mostly due to less of a wobble to confirm. Meanwhile switching to continuous AFC mode speeds-up the process and eliminates the wobble again due to the AF system exploiting the phase-detect system.
Here’s the same test but for video, with the Sigma 23 on the left at f1.4 and the Sony 24 on the right at f1.8, both using a single AF area in the middle and with continuous autofocus. You can see both lenses are capable of smooth focus pulls without wobbles for video, although do so at different speeds here with the camera’s default settings. Note some bodies may allow you to adjust the racking speed and response.
Next for face tracking, starting with the Sigma 23 wide-open at f1.4 but this time using the full AF area with face and eye detection. Here you can see the lens and camera easily refocusing on me as I move around the frame. You can also see how this focal length and aperture are ideal for filming pieces to camera – again it’s what I use for most of my YouTube videos.
Let’s put the Sigma 23 on the left and compare it to the Sony 24 on the right, both at their maximum apertures of f1.4 and f1.8 respectively. Both are clearly good at this particular job, and we’ll be taking a closer look at how they render the backgrounds in just a moment, but first focus breathing.
Here’s the Sigma 23 at f16, manually focusing from infinity to the closest distance and back again where you’ll notice the field of view shrinking at closer focus. Sorry for the wobbling here as it’s an unstablised system on the A6400.
And for comparison, here’s the Sigma 23 on the left versus the Sony 24 on the right, both at f16 and manually focusing from infinity to their closest distances and back again, where you’ll notice the Sony on the right exhibiting virtually no breathing at all. And impressively the Sony is also focusing closer at the extreme-end, so a great result from this older lens here.
Ok, now for my optical tests, starting with my distant landscape scene, angled so that details run into the corners. You’re looking at the Sigma 23mm at f1.4 here, mounted on an A7 IV body in APSC mode since I needed faster shutter speeds with the aperture wide-open than my A6400 allowed.
Since the Sigma lens is designed to be used with a profile, all of the images and results I’m showing you have Distortion Compensation set to Auto in the Sony menu, where it corrects for some mild barrelling.
Let’s zoom-in for a closer look at the middle of the frame with the Sigma 23 on the left and the Sony 24 on the right, both at their maximum apertures of f1.4 and 1.8 respectively.
Looking beyond the slightly different lighting conditions shows both lenses delivering good results in the middle of the frame right out of the gate with minimal benefits to stopping-down any further.
Now let’s return to the Sigma sample at f1.4, before heading into the far corner where there’s some of the usual darkening due to vignetting, but on the whole respectably sharp details. I’ll keep the Sigma on the left at f1.4 and compare it against the Sony 24 at f1.8 on the right, showing a slightly different part of the pier due to its slightly longer focal length.
But looking at the pier legs on both crops clearly shows the Sigma 23 on the left taking the lead in sharpness when both lenses have their apertures wide-open. As I gradually close the apertures on both lenses, you’ll see the vignetting lifting, but the Sigma remaining ahead on corner sharpness. Note this is with both lenses focused in the middle of the frame, so is also an indicator of field flatness. The Sony can be sharp in the corners, but you’ll need to focus there, or close the aperture down.
Moving onto portraiture, the 35 equivalent focal length is great for wider compositions that show a little more of the surroundings without too much distortion to worry about.
Here’s the Sigma 23 at f1.4 where you can also get an idea of the amount of blurring possible in the background and the rendering style. Just for comparison, here’s the Sony 24 from the same distance at its maximum aperture of f1.8 where you can see its slightly tighter field of view and rendering style.
Now for a closer look with the Sigma 23 on the left and the Sony 24 on the right, again at their maximum apertures. When viewed in isolation, both are capable of sharp portrait details, but side-by-side, the newer Sigma lens on the left is visibly crisper, while also delivering slightly less busy-looking bokeh in the background. Rendering is always a personal choice, but I’m preferring the Sigma here, although note both lenses are showing evidence of LoCA fringing here.
Next for my bokeh ball test with the Sigma 23 wide-open at f1.4 and focused close to its minimum distance of around 25cm. Let’s briefly toggle between it and the Sony 24 from the same distance and position at f1.8. Notice how the Sigma is actually delivering a similarly-sized subject to the Sony – maybe even a tad larger – despite its slightly shorter focal length. This is due to a mild magnification from focus breathing at close range as demonstrated earlier.
Taking a closer look at both samples with the Sigma 23 on the left and the Sony 24 on the right shows both lenses exhibiting some outlining and textures within the blobs, but I’d say the Sigma blobs are a little cleaner inside and larger too thanks to its larger aperture.
As I gradually close their apertures, you’ll see the impact of their respective diaphragm blade systems, with the Sigma on the left rendering the rounder shapes we’re more used to seeing on newer lens designs versus the more angular shapes of older models. There’s no right or wrong here, only personal preference.
While focus breathing helps the Sigma achieve similar magnification to the Sony from the same distance though, the Sony lens can focus much closer.
Here’s the Sigma 23 focused as close as I could to the ruler, where it’s reproducing a subject measuring around 138mm across the frame. I’ll keep the Sigma image at the top and compare it against the Sony at the bottom from its closer minimum focusing distance of 16cm where it’s reproducing 92mm across the frame.
Personally speaking, the closer focusing distance of the Sony lens has proven very useful when filming small details on the products I review on YouTube and gives it greater flexibility for me, but of course your mileage may vary.
At this point I’d normally wrap-up my review, but I’ve one final test for you which actually proved to be a bit of a surprise. As you know, both lenses are designed for use on cameras with cropped APSC sensors, and as such you wouldn’t expect their imaging circles to extend much beyond the corners of this smaller frame. But since I had an A7 IV to hand, I thought I’d try both lenses with the camera using its full sensor coverage.
Here’s the Sony 24 in the cropped APSC mode which it’s designed for, followed by the camera set to full-frame where you’ll see the imaging circle as expected. No surprises here.
But now let’s compare it to the Sigma 23 in full-frame mode, and while some of the imaging circle remains visible as expected, it’s far less extreme than the Sony. Now to be fair, neither lens is designed to be used like this, but you can still see how the Sigma not only has a larger imaging circle, but one that remains respectably sharp well beyond the APSC frame size.
To better illustrate the difference in their imaging circles, I’ll toggle between a blank wall photographed with both lenses on a full-frame camera. Again this is not how they’re meant to be used, but the Sigma clearly has some potential for owners of full-frame bodies if they’re willing to apply a mild crop, perhaps when exploiting digital stabilisation on video.Check prices on the Sigma 23mm f1.4 DC DN at B&H, Adorama, WEX UK or Calumet.de. Alternatively get yourself a copy of my In Camera book, an official Cameralabs T-shirt or mug, or treat me to a coffee! Thanks!