Sigma 10-20mm f/4-5.6 EX DC HSM APS-C Lens for Canon EF-S Mount {77}

Sigma's 10-20mm ultra-wide zoom built for APS-C shooters.

On a Canon APS-C body, 10mm delivers a field of view that architecture photographers and landscape shooters genuinely need, wide enough to work inside tight interiors or pull in a full ridgeline without stitching. The 10-20mm f/4-5.6 range covers real-world shooting distances without distortion becoming a liability, and the HSM (Hyper Sonic Motor) autofocus keeps acquisition quiet and fast enough for candid work. The 77mm filter thread is a practical bonus: it's a common filter size, so you're not buying a dedicated set of NDs or polarizers just for this glass.

The EX designation in Sigma's lineup signals their professional-grade optical and mechanical construction standard. Stopping down to f/8 or f/11 gives landscapes the front-to-back sharpness that wide primes used to own exclusively. For Canon crop-sensor shooters who want a dedicated ultra-wide without jumping to full-frame glass with an adapter, this lens was designed from the ground up for the format, the DC designation means the image circle is matched to APS-C, keeping the optics compact and the weight manageable on a day-long shoot.

Who It's For

Travel and architectural photographers working on APS-C Canon bodies will find the 10mm end genuinely useful for tight interiors, narrow streets, and environmental portraits where backing up isn't an option. Landscape photographers benefit from the f/8-f/11 sweet spot at wider focal lengths, where depth of field control matters more than speed. Documentary and photojournalist shooters who need a wide zoom with HSM autofocus for quiet operation in sensitive environments get that here. Event photographers covering venues with spatial constraints will use the full 10-20mm zoom range within a single room.

Key Features

• 10-20mm focal range with f/4-5.6 maximum aperture
• HSM autofocus system for fast, quiet focus acquisition
• 77mm filter thread accepts standard ND and polarizing filters
• EX-series optical construction for professional-grade sharpness
• DC optics optimized specifically for APS-C sensor coverage
• Compact, lightweight design suitable for day-long shooting

FAQ

What's the actual field of view on a Canon APS-C body?

At 10mm you're looking at roughly 104 degrees - wide enough for interior architecture and tight landscapes. The 20mm end sits around 62 degrees, giving you a legitimate telephoto option within the ultra-wide range.

Does the HSM autofocus work on all Canon EF-S bodies?

Yes. HSM (Hyper Sonic Motor) is compatible with any Canon EF-S mount camera. It's quieter and faster than Canon's older AF motors, which matters for candid shooting.

Why does the aperture change from f/4 to f/5.6?

At 10mm the maximum aperture is f/4, but as you zoom to 20mm it stops down to f/5.6. This is typical for zoom lenses - maintaining f/4 across the entire range would require significantly more glass and weight.

Is distortion really manageable at 10mm?

Barrel distortion is present at the wide end, but it's controlled by Sigma's optical design and becomes negligible once you stop down past f/8. For architecture, shooting at f/11 gives you both distortion control and front-to-back sharpness.

Will standard filters work with the 77mm thread?

Yes. 77mm is one of the most common filter sizes - your existing NDs, polarizers, and UV filters will mount directly without adapters.

How does this compare to Canon's own 10-22mm EF-S lens?

Canon's 10-22mm is sharper at f/2.8 maximum aperture and covers 1.2mm more on the telephoto end. This Sigma is more compact, lighter, and typically costs less - trade-offs are typical in the ultra-wide range.