Rank #2 in Best Telephoto Zoom Lens 2026: 8 Ranked, and Two Spec Sheets That Don't Add Up
Canon RF 100-400mm F5.6-8 IS USM
Price and rating as shown on Amazon when we collected them. Both change.
The Canon RF 100-400mm F5.6-8 IS USM sits at number 2 in this guide at £599.00, with 4.6 out of 5 from 754 ratings. It is a telephoto zoom for Canon EOS R system bodies, sold as compact and light: the listing gives 635g and 164.7mm, a 5.5-stop optical image stabiliser and Ultra-Low Dispersion glass.
The detail that stands out here is that the listing's own fields disagree with each other. It carries a Fixed Focal Length of "400 Millimetres" on a lens the same listing calls a zoom with a 4:1 ratio and a 100-400mm range. One bullet credits "STM autofocus" while the product name and another field say USM. And the rating bars shown add up to 100 while the headline figure is 754 ratings. That is why the placing here leans on the focal range in the name, the price and the spread of ratings rather than on the numeric fields. Every figure on this page comes from the Amazon listing, not from testing of our own.
How those 754 ratings break down
An average hides its own shape. This is the spread behind the 4.6 stars.
Specification
Exactly as published on the Amazon listing, field for field.
| Price | £599.00 |
|---|---|
| Rating | 4.6 out of 5, from 754 ratings |
| Focal range (from the product name) | 100-400mm |
| Aperture range (from the product name) | F5.6-8 |
| Maximum aperture / minimum aperture (as listed) | 5.6 f / 8.0 |
| Fixed focal length (as listed) | 400 Millimetres — on a lens whose design is listed as Zoom |
| Weight and length (as listed) | 635g, 164.7mm |
| Image stabilisation (as listed) | Optical, quoted at 5.5 stops |
What buyers actually say
Quoted from customer reviews on Amazon
Verified purchase“I bought this lens to fill a gap between lenses as I have a manual lens that goes from 400 to 800mm the idea being I could get out and about trying my hand at wildlife etc, I'm just amature having fun and I've had that with the RF 100-400mm which gives you easy to focus sharp shots, I've read in some reviews that it's light to hold that I found it slightly heavier than they were saying as for size it fits easily into my camera bag when you see how pricey it can be for a lens like this, this one is good quality.”
Verified purchase“This lens is light and performs well in good light. It focuses fast and is sharp wide open.I took this to Silverstone F1 2026 with my R10 and was able to shoot through catch fencing at 400mm f8, at f9+ it struggles to clear the catch fencing.I have previously used the Tamron EF 100-400 adapted to the R10, I preferred the colours slightly on that lens but the 500g+ weight trade off is not worth it.”
What it is up against
The rivals it was ranked against in Best Telephoto Zoom Lens 2026: 8 Ranked, and Two Spec Sheets That Don't Add Up.
Questions people ask
Will the Canon RF 100-400mm F5.6-8 IS USM fit my Canon EOS R camera?
The listing says it is compatible with any Canon EOS R System camera and gives Canon RF as the mounting.
Is this lens f/5.6 or f/8?
Both numbers appear in the product name as F5.6-8. Separately, the Maximum Aperture field says 5.6 f and the Minimum Aperture field says 8.0.
How many stops of stabilisation does the Canon RF 100-400mm offer?
The listing quotes a 5.5-stop optical image stabiliser, described as delivering sharp stills and smooth video.
What is the fixed focal length of the Canon RF 100-400mm?
The listing has a Fixed Focal Length field set to 400 Millimetres, even though the same listing describes the lens as a zoom with a 100-400mm range and a 4:1 zoom ratio.
Does it use USM or STM autofocus?
The product name says IS USM and one listing field says USM autofocus, while a bullet in the same listing says STM autofocus ensures fast, quiet and smooth focusing. The listing carries both.
How heavy is it in practice?
The listing gives 635g and 164.7mm and calls it compact and lightweight. One buyer wrote that they found it slightly heavier to hold than the reviews they had read had suggested.
Comments
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