Lens comparison · Canon RF / RF-S · updated 5 November 2026

Canon RF-S 18-45mm f/4.5-6.3 IS STM vs Sigma 18-50mm f/2.8 DC DN Contemporary

Canon RF-S 18-45mm f/4.5-6.3 IS STM18-45mm · f/4.5-6.3 · 130g
Sigma 18-50mm f/2.8 DC DN Contemporary18-50mm · f/2.8 · 290g
Verdict

Sigma 18-50mm f/2.8 DC DN Contemporary has more in its favour on paper. The 18-50mm f/2.8 DC DN Contemporary gathers more light for low light and background blur; the RF-S 18-45mm f/4.5-6.3 IS STM is lighter and cheaper. The Canon lens is the mount maker's own, while the Sigma is a third-party alternative.

Choose the RF-S 18-45mm f/4.5-6.3 IS STM for

  • less weight (130g vs 290g)
  • a lower price (about £70 vs £420)
  • optical stabilisation

Choose the 18-50mm f/2.8 DC DN Contemporary for

  • a brighter maximum aperture (f/2.8, about 1.4 stops more light)
  • more reach (50mm vs 45mm)
  • weather sealing
  • a constant aperture through the zoom range
RF-S 18-45mm f/4.5-6.3 IS STM18-50mm f/2.8 DC DN Contemporary
BrandCanonSigma
Focal length18-45mm18-50mm
Maximum aperturef/4.5-6.3f/2.8
Weight130 g290 g
StabilisationYesNo
Weather sealingNoYes
Filter size49mm55mm
Made forAPSCAPSC
New price£299£499
Used at MPB (Canon RF / RF-S)£62–£73£414–£429

More lens comparisons

E 16-55mm f/2.8 G vs 18-50mm f/2.8 DC DN ContemporaryXC 15-45mm f/3.5-5.6 OIS PZ vs 18-50mm f/2.8 DC DN Contemporary

See all Canon RF / RF-S cameras and lenses.

Frequently asked questions

Is the Canon RF-S 18-45mm f/4.5-6.3 IS STM better than the Sigma 18-50mm f/2.8 DC DN Contemporary?

The RF-S 18-45mm f/4.5-6.3 IS STM offers less weight (130g vs 290g), a lower price (about £70 vs £420), optical stabilisation; the 18-50mm f/2.8 DC DN Contemporary offers a brighter maximum aperture (f/2.8, about 1.4 stops more light), more reach (50mm vs 45mm), weather sealing.

Which is better value, the RF-S 18-45mm f/4.5-6.3 IS STM or the 18-50mm f/2.8 DC DN Contemporary?

On Canon RF / RF-S, the Canon RF-S 18-45mm f/4.5-6.3 IS STM costs about £70 against about £420 for the Sigma 18-50mm f/2.8 DC DN Contemporary (MPB used where listed, otherwise new; checked 5 November 2026).

Is f/2.8 worth it over f/4.5?

f/2.8 gathers about 1.4 stops more light, which helps indoors, at night and for background blur. If you mostly shoot in good light, the slower lens is usually lighter and cheaper.

Do both lenses fit the same cameras?

Both are available for Canon RF / RF-S (and other mounts: Sony E / FE, Fujifilm X, L-Mount). Both are made for crop sensors.