Over the last couple of years, Canon has released no fewer than four EOS R mirrorless cameras with APS-C sensors: the R7, R10, R50 and R100—in descending order of price and performance. But underwater shooters have a limited choice when it comes to Canon RF-mount lenses specifically designed for cropped sensors. There are just two: the Canon RF-S 18–45mm f/4.5–6.3 IS STM, with its 29–72mm equivalent focal length, which is perfect for fish portraits and combines well with macro and wide-angle wet lenses; and the Canon RF-S 10–18mm f/4.5–6.3 IS STM, which has a 16–29mm equivalent zoom range that makes it a solid choice for shooting reefscapes, wrecks and big animals.
Today, finally, a couple of alternatives have been announced: Sigma is now offering its 18–50mm f/2.8 DC DN and 10–18mm f/2.8 DC DN lenses with the Canon RF mount. In both cases, L-mount, Sony E-mount and Fujifilm X-mount versions are already available.
Both the 18–50mm f/2.8 and the 10–18mm f/2.8 are constructed using 13 elements in 10 groups and feature 7 diaphragm blades. The 18–50mm f/2.8 measures 2.9in (74.5mm) in length, weighs 10.2oz (290g), and boasts a minimum focusing distance of just 4.8in (12.1cm), while the 10–18mm f/2.8 is slightly shorter, at 2.4in (62mm), weighs an ounce less, at 9.2oz (260g), and focuses just a little closer, at 4.6in (11.6cm). With their significant speed advantage over the Canon equivalents, both these new Sigma lenses could prove to be optically more impressive as well.
The Sigma 10–18mm f/2.8 DC DN and 18–50mm f/2.8 DC DN are priced at $600 and $550, respectively.
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