Canon RF 100-400mm f/5.6-8 IS USM vs Sigma 10-18mm f/2.8 DC DN Contemporary (Canon RF)
The bottom line
These cover different focal lengths — the Canon RF 100-400mm f/5.6-8 IS USM is 100-400mm, the Sigma 10-18mm f/2.8 DC DN Contemporary (Canon RF) is 10-18mm — so they're not really substitutes. Pick by the field of view you actually need: the Canon RF 100-400mm f/5.6-8 IS USM for super-telephoto, the Sigma 10-18mm f/2.8 DC DN Contemporary (Canon RF) for wide-angle.
Choose the Canon RF 100-400mm f/5.6-8 IS USM if…
- ✓You need more reach — it goes to 400mm vs 18mm for distant subjects, wildlife and sport.
- ✓You shoot handheld or on an unstabilised body — it has optical stabilisation, the other doesn't.
- ✓You like close-focus work — 0.41x magnification vs 0.28x.
Choose the Sigma 10-18mm f/2.8 DC DN Contemporary (Canon RF) if…
- ✓You want more light and background blur — f/2.8 is faster than f/5.6, better for low light and subject separation.
- ✓You shoot wide — it starts at 10mm vs 100mm for landscapes, interiors and architecture.
- ✓You value portability — at 260g (9.2 oz) it's lighter than the 635g (1.40 lb) alternative for travel and all-day carry.
- ✓You work outdoors — it's weather-sealed against dust and moisture; the other isn't.
Where they differ
- ›Aperture: the Sigma 10-18mm f/2.8 DC DN Contemporary (Canon RF) opens to f/2.8 vs the Canon RF 100-400mm f/5.6-8 IS USM's f/5.6 — more light and shallower depth-of-field.
- ›Focal range: Canon RF 100-400mm f/5.6-8 IS USM is 100-400mm, Sigma 10-18mm f/2.8 DC DN Contemporary (Canon RF) is 10-18mm — different framing and reach.
- ›Stabilisation: only the Canon RF 100-400mm f/5.6-8 IS USM has optical stabilisation — steadier handheld shots, especially on bodies without IBIS.
- ›Weight: the Sigma 10-18mm f/2.8 DC DN Contemporary (Canon RF) is 260g (9.2 oz) vs 635g (1.40 lb) — you'll feel the difference handheld.
- ›Durability: the Sigma 10-18mm f/2.8 DC DN Contemporary (Canon RF) is weather-sealed; the other isn't.
Frequently asked
Is the Canon RF 100-400mm f/5.6-8 IS USM or the Sigma 10-18mm f/2.8 DC DN Contemporary (Canon RF) better?
These cover different focal lengths — the Canon RF 100-400mm f/5.6-8 IS USM is 100-400mm, the Sigma 10-18mm f/2.8 DC DN Contemporary (Canon RF) is 10-18mm — so they're not really substitutes. Pick by the field of view you actually need: the Canon RF 100-400mm f/5.6-8 IS USM for super-telephoto, the Sigma 10-18mm f/2.8 DC DN Contemporary (Canon RF) for wide-angle.
Who should choose the Canon RF 100-400mm f/5.6-8 IS USM?
Choose the Canon RF 100-400mm f/5.6-8 IS USM if you need more reach — it goes to 400mm vs 18mm for distant subjects, wildlife and sport. Choose it if you shoot handheld or on an unstabilised body — it has optical stabilisation, the other doesn't. Choose it if you like close-focus work — 0.41x magnification vs 0.28x.
Who should choose the Sigma 10-18mm f/2.8 DC DN Contemporary (Canon RF)?
Choose the Sigma 10-18mm f/2.8 DC DN Contemporary (Canon RF) if you want more light and background blur — f/2.8 is faster than f/5.6, better for low light and subject separation. Choose it if you shoot wide — it starts at 10mm vs 100mm for landscapes, interiors and architecture. Choose it if you value portability — at 260g (9.2 oz) it's lighter than the 635g (1.40 lb) alternative for travel and all-day carry. Choose it if you work outdoors — it's weather-sealed against dust and moisture; the other isn't.
What is the main difference between the Canon RF 100-400mm f/5.6-8 IS USM and the Sigma 10-18mm f/2.8 DC DN Contemporary (Canon RF)?
Aperture: the Sigma 10-18mm f/2.8 DC DN Contemporary (Canon RF) opens to f/2.8 vs the Canon RF 100-400mm f/5.6-8 IS USM's f/5.6 — more light and shallower depth-of-field.
| Product | ||
|---|---|---|
| Optical Design | ||
| Focal Length | 100-400mm | 10-18mm |
| Lens Type | Zoom | Zoom |
| Optical Elements | 18 | 13 |
| Optical Groups | 12 | 10 |
| Aperture & Iris | ||
| Maximum Aperture | f/5.6 | f/2.8 |
| Minimum Aperture | f/32 | f/22 |
| Aperture Blades | 9 | 9 |
| Rounded Aperture | Yes | Yes |
| Coverage & Angle | ||
| Format Coverage | Full-Frame | APS-C |
| Lens Mount | Canon RF | Canon RF |
| Angle of View | 24° – 6° | 110° – 76° |
| 35mm Equivalent | − | 16-29mm |
| Focus | ||
| Autofocus | Yes | Yes |
| Focus Motor | Nano USM | HLA |
| Focus Limiter | No | No |
| AF/MF Switch | Yes | Yes |
| Min Focus Distance | 88 cm | 12 cm |
| Max Magnification | 0.41x | 0.28x |
| Stabilization & Video | ||
| Optical Stabilization | Yes | No |
| Aperture Ring | No | Yes |
| Declickable Aperture | No | Yes |
| Parfocal | No | No |
| Internal Zoom | No | No |
| General | ||
| Price (MSRP) | $649 | $699 |
| Filter Size | 67mm | 67mm |
| Diameter | 79mm | 67.2mm |
| Length | 147mm | 73.3mm |
| Weight | 635g (1.40 lb) | 260g (9.2 oz) |
| Weather Sealed | No | Yes |
| Tripod Collar | No | No |
