Canon RF 100-400mm f/5.6-8 IS USM vs Sigma 15mm F1.4 DC 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 15mm F1.4 DC Contemporary (Canon RF) is 15mm — 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 15mm F1.4 DC 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 15mm for distant subjects, wildlife and sport.
- ✓You want one-lens flexibility — a 100-400mm zoom covers what the fixed 15mm can't reframe.
- ✓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 0.15x.
Choose the Sigma 15mm F1.4 DC Contemporary (Canon RF) if…
- ✓You want more light and background blur — f/1.4 is faster than f/5.6, better for low light and subject separation.
- ✓You shoot wide — it starts at 15mm vs 100mm for landscapes, interiors and architecture.
- ✓You prefer a fast, compact single focal length — a 15mm prime over a zoom.
- ✓You value portability — at 220g (7.8 oz) it's lighter than the 635g (1.40 lb) alternative for travel and all-day carry.
Where they differ
- ›Aperture: the Sigma 15mm F1.4 DC Contemporary (Canon RF) opens to f/1.4 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 15mm F1.4 DC Contemporary (Canon RF) is 15mm — different framing and reach.
- ›Type: the Canon RF 100-400mm f/5.6-8 IS USM is a zoom (flexible framing), the Sigma 15mm F1.4 DC Contemporary (Canon RF) a prime (one focal length, usually brighter and lighter).
- ›Stabilisation: only the Canon RF 100-400mm f/5.6-8 IS USM has optical stabilisation — steadier handheld shots, especially on bodies without IBIS.
- ›Close-up: the Canon RF 100-400mm f/5.6-8 IS USM reaches 0.41x magnification vs 0.15x — more for close-up and macro work.
- ›Weight: the Sigma 15mm F1.4 DC Contemporary (Canon RF) is 220g (7.8 oz) vs 635g (1.40 lb) — you'll feel the difference handheld.
Frequently asked
Is the Canon RF 100-400mm f/5.6-8 IS USM or the Sigma 15mm F1.4 DC 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 15mm F1.4 DC Contemporary (Canon RF) is 15mm — 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 15mm F1.4 DC 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 15mm for distant subjects, wildlife and sport. Choose it if you want one-lens flexibility — a 100-400mm zoom covers what the fixed 15mm can't reframe. 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 0.15x.
Who should choose the Sigma 15mm F1.4 DC Contemporary (Canon RF)?
Choose the Sigma 15mm F1.4 DC Contemporary (Canon RF) if you want more light and background blur — f/1.4 is faster than f/5.6, better for low light and subject separation. Choose it if you shoot wide — it starts at 15mm vs 100mm for landscapes, interiors and architecture. Choose it if you prefer a fast, compact single focal length — a 15mm prime over a zoom. Choose it if you value portability — at 220g (7.8 oz) it's lighter than the 635g (1.40 lb) alternative for travel and all-day carry.
What is the main difference between the Canon RF 100-400mm f/5.6-8 IS USM and the Sigma 15mm F1.4 DC Contemporary (Canon RF)?
Aperture: the Sigma 15mm F1.4 DC Contemporary (Canon RF) opens to f/1.4 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 | 15mm |
| Lens Type | Zoom | Prime |
| Optical Elements | 18 | 13 |
| Optical Groups | 12 | 11 |
| Aperture & Iris | ||
| Maximum Aperture | f/5.6 | f/1.4 |
| Minimum Aperture | f/32 | f/16 |
| 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° | 82.9° |
| 35mm Equivalent | − | 24-24mm |
| Focus | ||
| Autofocus | Yes | Yes |
| Focus Motor | Nano USM | HLA |
| Focus Limiter | No | No |
| AF/MF Switch | Yes | Yes |
| Min Focus Distance | 88 cm | 18 cm |
| Max Magnification | 0.41x | 0.15x |
| 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 | $579 |
| Filter Size | 67mm | 58mm |
| Diameter | 79mm | 64mm |
| Length | 147mm | 65mm |
| Weight | 635g (1.40 lb) | 220g (7.8 oz) |
| Weather Sealed | No | Yes |
| Tripod Collar | No | No |
