Sigma made two 10-20mm EX DC HSM ultra wide zooms for APS-C cameras: one with a variable f/4-5.6 aperture and one with a constant f/3.5 aperture. The f/3.5 version gathers more light at every focal length and usually costs you more in size and weight. The f/4-5.6 version is the lighter, simpler travel option. Confirm exact specs and mount availability with Sigma’s materials or a trusted listing.
What Each Lens Is For
Both lenses are built for cropped sensor cameras, which is what the DC designation means. They give a very wide view for landscapes, architecture, interiors and creative perspective work. Neither is designed for full frame bodies, so check that your camera uses an APS-C sensor.
Key Differences
- Aperture behavior: The f/3.5 lens holds its maximum aperture across the zoom. The f/4-5.6 lens loses some light as you zoom toward 20mm.
- Size and weight: The constant aperture design is generally larger and heavier. Compare the numbers on Sigma’s pages.
- Low light and astro: The brighter lens is easier to use in dim interiors and for night skies, where every bit of light helps.
- Filters: Ultra wide lenses can have bulbous front elements or large threads that limit filter use. Check the filter situation for each version before buying.
- Autofocus motor: Both use Sigma’s HSM motor on supported mounts. Older designs may behave differently on newer camera bodies.
| Factor | f/4-5.6 | f/3.5 |
|---|---|---|
| Aperture | Variable | Constant |
| Handling | Lighter, easier to carry | Larger, brighter |
| Best for | Travel, daylight scenes | Low light, interiors, night skies |
How to Decide
- Think about when you shoot. Mostly daylight landscapes rarely need the extra light.
- Consider how far you walk with the lens. A smaller lens is easier to keep in the bag.
- If you shoot interiors or night skies handheld or on a tripod, extra brightness helps keep ISO lower.
- Check used market condition carefully, because both are older designs. Look for smooth zoom and focus action and clean glass.
- Confirm your camera mount is supported and ask whether the lens needs any adjustments for your body.
Extra Tip
Whichever lens you choose, shoot a few frames at different apertures and zoom positions soon after buying it. This shows you where it looks sharpest and helps you spot a faulty copy while a return is still possible.
FAQ
Will these lenses work on a full frame camera?
They are designed for APS-C. On full frame bodies they may force a crop or show dark corners, so use them on cropped sensor cameras.
Which has the wider view?
Both cover the same stated focal range of 10 to 20mm, so the angle of view is similar. The difference lies in brightness and size.
The Short Version
Choose the f/3.5 version for low light work, interiors and night skies, and accept the extra bulk. Choose the f/4-5.6 version for lighter carry and daytime shooting. We have not used these lenses ourselves, so verify details before buying.
