Canon
Canon RF 100-400mm f/5.6-8
Prime/Zoom
84
/ 100
From $649
VS
Tamron 20-40mm f/2.8 Di III VXD wins by 1
Tamron
Tamron 20-40mm f/2.8 Di III VXD
Prime/zoom
85
/ 100
From $699
Specdex verdict
Tamron 20-40mm f/2.8 Di III VXD takes it — here’s why.
In our weighted Specdex score, Canon RF 100-400mm f/5.6-8 lands at 84 and Tamron 20-40mm f/2.8 Di III VXD at 85. That puts Tamron 20-40mm f/2.8 Di III VXD ahead by 1 points — a narrow margin driven mostly by its strengths in the categories below.
Pick Canon RF 100-400mm f/5.6-8 if…
- ✓Fast aperture
- ✓Quiet autofocus
- ✓Weather-sealed (most)
Pick Tamron 20-40mm f/2.8 Di III VXD if…
- ✓Proven optical formula
- ✓Weather-sealing (L/GM/S)
- ✓Strong resale
Canon RF 100-400mm f/5.6-8 84
vs 85 Tamron 20-40mm f/2.8 Di III VXD
Score breakdown
Canon RF 100-400mm f/5.6-8
84 sharpness 84
af 82
build 88
value 85
Tamron 20-40mm f/2.8 Di III VXD
85 sharpness 85
af 81
build 90
value 86
Specs side-by-side
| Spec | Canon RF 100-400mm f/5.6-8 | Tamron 20-40mm f/2.8 Di III VXD |
|---|
Canon RF 100-400mm f/5.6-8
Pros
- +Fast aperture
- +Quiet autofocus
- +Weather-sealed (most)
Cons
- −Mount-specific
- −Weight varies
- −Price scales with quality
Tamron 20-40mm f/2.8 Di III VXD
Pros
- +Proven optical formula
- +Weather-sealing (L/GM/S)
- +Strong resale
Cons
- −Mount-specific
- −Older AF motor on some
- −Heavier than modern counterparts
FAQ: Canon RF 100-400mm f/5.6-8 vs Tamron 20-40mm f/2.8 Di III VXD
Which is better, Canon RF 100-400mm f/5.6-8 or Tamron 20-40mm f/2.8 Di III VXD? +
Tamron 20-40mm f/2.8 Di III VXD scores 85 on our weighted rubric — ahead by 1. Your best pick depends on the sub-scores above.
Is Canon RF 100-400mm f/5.6-8 worth the price? +
At $649, Canon RF 100-400mm f/5.6-8 delivers a Specdex score of 84 — strongest in build.
Is Tamron 20-40mm f/2.8 Di III VXD worth the price? +
At $699, Tamron 20-40mm f/2.8 Di III VXD delivers a Specdex score of 85 — strongest in build.
Does Canon RF 100-400mm f/5.6-8 or Tamron 20-40mm f/2.8 Di III VXD last longer? +
Based on our long-term update and support ratings, both ship with multi-year support. Battery and reliability scores are visible in the breakdown above.