There are lenses that earn their place in the bag permanently, and lenses that teach you something useful before moving on. The Sigma EX DG 12-24mm HSM f/4.5-5.6 belongs firmly in the second category. I used it for a sunset shoot on Ladle Hill near Watership Down with the Canon EOS 5DS R — conditions that should have played to a wide-angle landscape lens’s strengths. The results were good in several respects and honestly disappointing in one critical area. I have since sold the lens. This review tells you exactly why — and whether it might still be the right choice for you.
| Lens at a Glance — Sigma EX DG 12-24mm HSM f/4.5-5.6 | |
|---|---|
| Lens | Sigma EX DG 12-24mm HSM |
| Mount | Canon EF |
| Focal Range | 12–24mm |
| Maximum Aperture | f/4.5 (at 12mm) to f/5.6 (at 24mm) |
| Autofocus Motor | HSM (Hyper Sonic Motor) |
| Build | EX series — solid, weather-resistant construction |
| Filter Thread | No front filter thread — bulging front element |
| Camera Used | Canon EOS 5DS R (50.6MP) |
| Location | Ladle Hill / Watership Down, Hampshire |
| Conditions | Sunset — low light, high contrast |
| Current Status | Sold — edge softness unsatisfactory at 50MP |
What Is the Sigma EX DG 12-24mm HSM?
The Sigma EX DG 12-24mm HSM f/4.5-5.6 is a full-frame ultra-wide zoom lens, part of Sigma’s EX (Excellence) series — their professional-grade line distinguished by better build quality, improved optical coatings, and more robust construction than the standard range. At 12mm on a full-frame sensor it delivers an angle of view of approximately 122 degrees — genuinely extreme by any standard, and wider than anything in Canon’s own EF lens range at the time of its release.
The EX series build quality is immediately apparent. The barrel is solid, the mount is firm, and the overall construction has the reassuring density of something built to last. The bulging front element — necessary at this focal length and responsible for the lack of a standard filter thread — requires careful handling and a dedicated petal hood. The HSM autofocus motor is quiet and reasonably quick in good light, though in the low light of a Hampshire sunset I found manual focus more reliable, and the focus ring responds smoothly to a deliberate touch.
Ladle Hill at Sunset — The Perfect Wide-Angle Test
Ladle Hill sits on the chalk ridge immediately north of Watership Down, an Iron Age hillfort whose earthworks still rise and fall across the crown of the hill in a way that makes the whole site feel permanently on the edge of revealing something. The views from the top are among the finest in north Hampshire — south across the Test Valley, west into the Wiltshire downs, north across the Berkshire Vale. On a clear evening in late summer, with the sun dropping towards the western horizon and the Hampshire farmland laid out below in the particular warm light that August reserves for its last hour, it is one of the most photographically compelling viewpoints in the county.
It is also, in retrospect, one of the most demanding test grounds for a wide-angle lens. The 50.6-megapixel sensor of the Canon EOS 5DS R — with its cancelled anti-aliasing filter extracting maximum resolution from every corner of the frame — is entirely unforgiving of edge softness. What might pass unnoticed on a 24-megapixel file becomes apparent at 50 megapixels, and apparent at print sizes that this camera routinely produces. A wide-angle lens tested here either earns its resolution rating across the full frame or it does not. The Sigma, in honest assessment, did not quite earn it.
What the Sigma Did Well
At 12mm the sense of scale is immediate and extraordinary. Standing at the top of Ladle Hill watching the sun drop below the western horizon, the Sigma transformed the scene into something genuinely panoramic — the rolling hills stretched and curved across the frame, the clouds given a depth and movement that no standard wide angle could have delivered. The expansive field of view adds a drama to landscape photography that becomes addictive once you have experienced it. As the only lens that could offer this perspective on a Canon EF mount at the time, it occupied a unique creative position.
Flare control was better than I expected for a lens shooting directly into a strong sunset light. Even when I deliberately positioned the sun near the frame edge — the most demanding position for any lens’s coating — the result was controlled rather than chaotic, with a degree of veiling flare that added atmosphere without destroying the image. Colour rendering was warm and rich, the sunset hues coming through with a vibrancy that suited the Hampshire countryside’s particular palette of ochres and greens and deep sky blues.
Where the Sigma Fell Short
The problem became apparent when I examined the files at 100% on the 5DS R’s 50.6-megapixel output. Edge softness — a characteristic of almost all ultra-wide lenses to some degree — was more pronounced than I had hoped, and more pronounced than the lens’s EX series status had led me to expect. The centre of the frame was sharp and detailed, rendering the distant Hampshire countryside with good clarity. But towards the corners and edges, the resolution fell away in a way that became increasingly difficult to ignore at the enlargement sizes I regularly print to.
This is the fundamental tension in ultra-wide lens design: the optical compromises required to achieve a 122-degree field of view on a full-frame sensor are significant, and at extreme wide angles even excellent lenses struggle to maintain edge sharpness. The Sigma is not a poor lens — on a lower-resolution body, or for images viewed at smaller sizes, the edge softness would be far less apparent. But paired with a 50-megapixel body that reveals everything the negative contains, it showed its limits more clearly than I was comfortable with for serious landscape work. I subsequently sold it and have not replaced it with another ultra-wide — the Canon RF 28mm f/2.8 STM covers the wide end of my current landscape work with sharper results across the full frame.
At 12mm the world opens up in a way that is genuinely thrilling. But on a 50-megapixel sensor the edges of that open world need to be as sharp as the centre — and the Sigma, on honest examination, could not quite manage it.
Who the Sigma 12-24mm Is and Isn’t For
| This Lens Suits | This Lens May Not Suit |
|---|---|
| Photographers using bodies below 30MP | High-resolution bodies (40MP+) where edge softness is more visible |
| Landscape work viewed at moderate sizes | Large-format printing where corner resolution is critical |
| Creative ultra-wide work embracing distortion | Architectural photography requiring straight lines |
| Canon EF mount users needing extreme width | Canon RF mount users — native options now available |
| Photographers on a budget for ultra-wide work | Those who pixel-peep or demand consistent sharpness edge to edge |
What Works Well
- Extraordinary 12mm field of view — genuinely unique creative perspective
- Good colour rendering — warm and vibrant in sunset conditions
- Better flare control than expected for an extreme wide angle
- Solid EX series build quality — robust and well-constructed
- HSM autofocus quiet and responsive in good light
- Smooth manual focus ring for precise control in low light
- Good value at current second-hand prices
Worth Knowing
- Edge softness noticeable on high-resolution bodies (40MP+)
- Significant distortion at 12mm — curves straight lines visibly
- No front filter thread — bulging element requires dedicated accessories
- Not weather sealed to the same standard as Canon L-series glass
- EF mount only — requires adapter on Canon RF bodies
- Specialised focal length — not an everyday or versatile lens
Is the Sigma EX DG 12-24mm HSM sharp?
In the centre of the frame, yes — it is sharp and delivers good detail in good light. Towards the edges and corners it softens, and this softness becomes increasingly apparent on higher-resolution bodies. On the Canon EOS 5DS R at 50.6 megapixels I found it too soft at the edges for my landscape printing requirements. On a body of 24 megapixels or below, the edge performance would be less visible and the lens considerably more usable. For a sharper wide-angle alternative on the Canon RF system, see my review of the Canon RF 28mm f/2.8 STM.
Is the Sigma 12-24mm good for landscape photography?
For landscape work viewed at moderate sizes or on lower-resolution bodies, yes — the 12mm field of view delivers a sense of scale and drama that is genuinely compelling, and the colour rendering in golden hour light is warm and pleasing. For large-format printing from a high-resolution body, the edge softness is a limitation that is difficult to overlook. For my landscape work I now use the Canon RF 28mm f/2.8 STM for wide work and the Canon L Series 24-70mm for greater versatility. See my guide to photographing British landscapes for more on focal length choices.
Does the Sigma 12-24mm work on Canon mirrorless cameras?
It works on Canon RF bodies via the Canon EF-EOS R adapter, but the EF mount and adapter combination adds bulk and the autofocus, while functional, does not perform at the same level as native RF glass. If you are shooting on a Canon RF body and need an ultra-wide option, native RF mount lenses are worth considering for the autofocus and handling benefits. See my review of the Canon EOS R5 for more on the RF system and adapter performance.
Why did you sell the Sigma 12-24mm?
Edge softness on the Canon EOS 5DS R’s 50.6-megapixel sensor. The centre sharpness was acceptable but the corners and edges fell away more than I was comfortable with for the large-format landscape prints I produce. On a lower-resolution body the same softness would be far less apparent. It was not a bad lens — it was the wrong lens for my specific combination of body and output size. I sold it and have not found a compelling reason to replace it with another ultra-wide for my current work.
Is the Sigma 12-24mm still worth buying second hand?
At its current second-hand price, conditionally yes — for photographers using lower-resolution bodies who need an affordable ultra-wide EF-mount option. It is a legitimate creative tool that delivers a perspective unavailable from any other lens in the Canon EF range. Just be clear-eyed about the edge softness limitation before purchasing, and test it thoroughly on your specific body before committing to it for important work.
This article is part of my Photography Kit Reviews hub. For more lens and camera reviews, see my guides to the Canon RF 28mm f/2.8 STM, Canon RF 200-800mm, Canon EOS R5, and Canon EOS 5DS R. For my film photography work, visit my Film Photography hub.
