Sigma 10-20mm f/3.5 EX DC HSM APS-C Lens for Canon EF-S Mount {82}

Sigma's f/3.5 ultra-wide zoom built for APS-C shooters

The 10-20mm f/3.5 EX DC HSM gives Canon APS-C bodies a field of view equivalent to roughly 16-32mm in full-frame terms, which puts serious wide-angle reach in a single zoom range. The constant f/3.5 aperture across the entire focal length is the defining spec here. Most wide zooms in this range use variable apertures, so you don't have to compensate exposure as you zoom in from 10mm to 20mm. That consistency matters when you're shooting in tight, low-light interiors or working fast.

The HSM (Hypersonic Motor) drive makes autofocus fast and near-silent, and it supports full-time manual focus override without switching modes. The 82mm filter thread is large but workable for those who want to use circular polarizers on landscape work. The EX designation reflects Sigma's professional-grade optical and mechanical construction standards. For APS-C Canon shooters who want a dedicated wide-angle workhorse without the compromises of a variable-aperture kit lens, this focal length range paired with a constant maximum aperture is a well-reasoned combination.

Who It's For

Architecture and interior photographers get a lot from the 10mm end, where the field of view is wide enough to work in confined spaces without distortion management becoming the whole job. Landscape shooters working on APS-C Canon bodies benefit from the constant f/3.5 when shooting golden hour or blue hour without a tripod. Event and documentary photographers covering venues with challenging light will find the fixed maximum aperture more predictable than variable-aperture alternatives. Street photographers who want a rectilinear ultra-wide for environmental context shots will find the 10-20mm range gives them room to work close without going fisheye.

Key Features

• Constant f/3.5 aperture across entire 10-20mm focal length
• HSM autofocus motor for fast, quiet focusing with full-time MF override
• 82mm filter thread for circular polarizers and ND filters
• Canon EF-S mount designed for APS-C sensor coverage
• EX-grade optical and mechanical construction
• 16-32mm full-frame equivalent field of view on APS-C bodies

FAQ

What's the full-frame equivalent focal length on an APS-C Canon body?

Roughly 16-32mm in full-frame terms, thanks to the 1.6x crop factor of APS-C sensors. That gives you serious wide-angle coverage without stepping up to a full-frame body or changing lenses.

Does the aperture stay constant across the zoom range?

Yes, it's f/3.5 from 10mm to 20mm. Most wide zooms in this price range use variable apertures that stop down as you zoom in, so you won't need to adjust exposure compensation when focal length changes.

How does the HSM autofocus perform?

The Hypersonic Motor is fast and nearly silent. You also get full-time manual focus override without flipping a switch, which is essential for precision work once you've locked focus.

Can I use filters on this lens?

Yes, it has an 82mm filter thread. That's larger than standard, but it's manageable if you want to run circular polarizers for landscape work or ND filters for long exposures.

What does the EX designation mean?

EX reflects Sigma's professional-grade optical and mechanical construction standards. You're getting better glass and more robust assembly than entry-level alternatives.

Is this lens weather-sealed?

No weather-sealing is mentioned in the specifications. Treat it as an unprotected optic in harsh conditions.

What's the minimum focus distance?

Specifications don't include minimum focus distance. Contact KEH or Sigma directly for that detail.