Canon 40mm f/2.8 STM vs Canon 50mm f/1.8

by Enche Tjin on June 24, 2012

Canon new prime lens, 40mm f/2.8 STM is one of the first pancake (very thin) lens and one of the first lens to have STM (stepper motor technology). STM technology makes sure that the lens autofocus smoothly when recording movies. According to recent reviews, this lens auto focus performance is fast and smooth, but still make an audible noise that could picked up while recording videos. AF performance is faster than regular lens, but slower than high-end USM lenses.

Canon also has Canon 50mm f/1.8 which is has some similarities with Canon 40mm but half the price and about 1.3 stop bigger maximum aperture. Which one is the right one for you? Let check out the specs.

Canon 50mm f/1.8 vs 40mm f/2.8

focal length: 50mm – 40mm (equiv. 80mm – 64mm)
max aperture: f/1.8 – f/2.8
weight: 130g – 130g
diameter: 52mm – 52mm
length: 22.8mm – 41mm
closest focusing distance: 0.45m – 0.3m
autofocus: regular motor – stepping motor (stm)
mount: EF, plastic – EF, metal
price: $75 vs $199


From the spec and illustration above, I’ll say that both lenses has some similarities: same diameter, same weight, both are quite small and compatible both for full frame or APS-C sized DSLR cameras.

The main advantages of the 50mm f/1.8 are:

  • Bigger aperture means more light and less depth of field
  • $124 cheaper
  • Longer focal length (better for close up portrait)
  • Easier to hold

Advantages of the 40mm f/2.8 STM are:

  • Smaller size
  • Consistent image quality at any aperture
  • More durable construction
  • Significantly faster and smoother auto focus
  • Wider focal length (better for landscape / environmental portrait)

Overall, Canon 40mm f/2.8 STM is a better lens. It produces consistent image quality, more durable and faster autofocus. However, it has awkward focal length that neither tele or wide. Canon 50mm f/1.8 has a bit longer focal length and bigger max aperture which is a bit better for portrait or close up photography.

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