Best fast normal prime for a Canon APS-C body: Canon 28mm f/1.8 vs Sigma 30mm f/1.4?

Asked 1/25/2011

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2 answers

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I’m choosing a fast, reasonably affordable normal prime for a Canon EOS 450D (APS-C) for available-light and street photography. A focal length around 28–30mm seems ideal.

The two main options I’m considering are the Canon EF 28mm f/1.8 USM and the Sigma 30mm f/1.4. My priorities are low-light performance, reliable autofocus, and overall image quality. I may eventually move to full frame, so lens compatibility matters too.

Specific questions:

  • How meaningful is the difference between f/1.4 and f/1.8 in real use?
  • Is the Canon’s autofocus noticeably better in practice?
  • Are the purple fringes/chromatic aberration on the Canon a real concern, and can a UV filter help?
  • Are there other lenses I should consider if I might switch to full frame later?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

15y ago

2 Answers

10

A few thoughts and links for your perusal:

  • Any reviews you're going to read will be subjective but they can be good data points. Here's a thread on DPreview comparing those two lenses as well as the FredMiranda review page for the Canon.
  • You did the right thing by trying out the lens for yourself.
  • It seems that the verdict is undecided on whether a UV filter can reduce chromatic aberrations. There is another question on this site about the downsides to using a UV filter.
  • The difference between f/1.4 and f/1.8 is 2/3 of a stop. You asked about how this would affect the shutter speed and this means that assuming all other conditions are the same, the faster glass (f/1.4) would allow for a shutter speed that's 66% faster than the slower glass (f/1.8).

Originally by user89. Source · Licensed CC BY-SA 4.0

user89

15y ago

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AI Answer

Generated from our catalog & community — verify before relying on it.

The biggest practical difference is aperture: f/1.4 is about 2/3 stop faster than f/1.8, so in the same light you can use a shutter speed roughly 66% faster. That is meaningful for handheld night and street shooting.

Between these two, the Sigma 30mm f/1.4 is often favored on APS-C because it was designed for that format and gives you the speed advantage. If APS-C is your main camera now, it’s a strong fit. If you later move to full frame, you can sell it and switch lenses.

The Canon 28mm f/1.8 has the advantage of full-frame compatibility, and its autofocus is generally regarded as good, but both lenses can show chromatic aberration/purple fringing wide open. That fringing is usually better handled in post-processing; a UV filter is not a reliable fix and can introduce drawbacks like extra flare.

Also keep in mind that many fast primes are softer wide open, so you may sometimes stop down a bit anyway.

If full-frame compatibility is the priority now, the Canon makes more sense. If low-light performance on your 450D matters most, the Sigma 30mm f/1.4 is the more compelling APS-C option.

UniqueBot

AI

15y ago

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