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Canon has unveiled the latest edition to its lineup of lenses designed for full-frame mirrorless cameras—and it seems destined to become a very significant lens for wide-angle underwater shooters. The RF 10–20mm f/4 L IS STM is the Japanese company’s widest RF-mount lens yet.

The new lens inevitably draws immediate comparisons with its counterpart in the DSLR world, the EF 11–24mm f/4 L, which has been a much-loved tool for capturing big animals, wrecks and reef scenics since 2015. Thanks to the technical innovations and design improvements the RF mount has made possible, the new RF lens offers a number of important advantages over the old EF lens.

Firstly, the RF 10–20mm f/4 offers a 130° field of view at 10mm compared to 126° at 12mm on the EF 11–24mm f/4. That 4° difference translates to a noticeably wider image field. Secondly, astonishingly, the RF 10–20mm f/4 weighs just 20.1oz (570g), half the weight of the EF 11–24mm f/4, which tips the scales at 41.6oz (1,179g). Thirdly, the new lens is only 4.4in (112mm) long, substantially shorter than the old lens, which is 5.2in (132mm). The RF 10–20mm is also a full inch (25.5mm) narrower at its maximum diameter than the EF 11–24mm. Finally, the new RF lens focuses somewhat closer than the old EF lens: 9.8in (25cm) versus 11in (28cm).

In terms of construction, the RF 10–20mm f/4 is composed of 16 elements across 12 groups, with one super ED and three ED elements. Ghosting is controlled via Canon’s SWC and ASC anti-reflection coatings. The ultra-wide zoom is the first L-series lens to use Canon’s STM focus drive motor technology for autofocus. Like other high-end lenses in the L series, the RF 10–20mm f/4 is dust and moisture resistant. Last but not least, the RF 10–20mm f/4—unlike its EF counterpart—is a stabilized lens, promising up to five stops of image stabilization (or up to six stops when combined with in-body image stabilization).

Available from early November from retailers such as Backscatter, the Canon RF 10–20mm f/4 L IS STM will have an MSRP of $2,300. (That’s not cheap, but it’s $700 less than the list price of the EF 11–24mm f/4!)
 

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