How much does autofocus performance vary in low light between camera bodies and lenses?
Asked 5/12/2012
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2 answers
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I use a Pentax K-x with a Sigma 30mm f/1.4, and in very low light the autofocus often won’t lock even when I can get a usable shot with manual focus. I’ve noticed other people shooting in dark bars with autofocus and it made me wonder: are low-light autofocus differences really that large between brands, camera models, and lenses? If autofocus struggles in dim light, is the main factor the body, the lens, or both?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
14y ago
2 Answers
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Yes, there are huge differences. Things are different between brands but there are even more differences between models.
The higher-end the model, the faster it focuses and conversely. Just this morning I was commenting to @rfusca who answered you already how slow the Nikon D3200 focuses. This model sits at the low-end of Nikon's lineup, just like your K-x in the Pentax lineup. The thing is that with Pentax you can only go one level up to a K-5 (or K-7) which improves things considerably. However, with Nikon or Canon, there are multiple levels to go up and they get considerably faster at autofocus.
Furthermore, lenses focus at different speeds. Worse even, they focus at different speeds on different bodies. Pentax, Nikon (except low-end Nikon DSLRs) and Sony support lenses which focus motors in the lens or using one in the body.
Generally but not always, brand lenses with in-focus motors are faster than those without. Off brand lenses have slower in-focus motors as far as I can tell but my sample is limited to 30 or so Sigma and Tamron ones (Only tried 1 Tokina).
More importantly, focus is always done with the aperture wide-open, so lenses with wider apertures have an advantage since the focus system has more light to work with.
Originally by user1620. Source · Licensed CC BY-SA 4.0
user1620
14y ago
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Generated from our catalog & community — verify before relying on it.
Yes — low-light autofocus can vary a lot, and the difference is often bigger between models and lenses than between brands alone.
From the answers here, three things matter most:
- camera body: higher-end bodies usually have better AF systems and tend to focus faster and more reliably in dim light than entry-level models.
- lens: some lenses focus much better than others in low light. Even on the same camera, one lens may hunt while another locks quickly.
- AF assist / technique: extra light helps. A flash or AF-assist lamp can make a big difference, and so can pre-focusing on a better-lit subject at the same distance.
A wide aperture helps exposure, but it does not guarantee good autofocus if the body or lens AF system struggles.
So yes, someone else’s Nikon or Canon could have focused much better than your setup — but that may be due to that specific body and lens combination, not just the brand name. Before changing systems, practical options include using AF assist, pre-focus techniques, or trying a different lens/body combination with stronger low-light AF.
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