Olympus OM-D E-M1 low light auto focus performance

Started 7 months ago | Questions thread
Timur Born
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Re: Olympus OM-D E-M1 low light auto focus performance
In reply to Brian Wadie, 7 months ago

Of course I chose conditions making the demonstration easy and reproducible. Noticed how normal refresh-rate changes AF speed when I switched exposure compensation from -2 to -1.7 EV? In those light conditions that was the breaking point where the camera slowed refresh-rate from 60 down to 30 fps in order to catch more light for Live View. This refresh-rate drop can also happen in more daylight situation when you pan the camera over a shadowy area, especially indoors with daylight coming from a window.

Also take note how the "Zoom AF" focusing algorithm works entirely different from normal AF and how it manages to focus on the blob of gray patch quite quickly where normal AF failed with both normal and high refresh-rates (high just hunting faster and giving up faster). There are situations where Zoom AF may fail while normal AF does not (especially using normal refresh-rate), but it's always worth a try if everything else fails. Once I find time I will have to compare Zoom AF on the E-M5 to the E-M1 as far as low light capabilities go.

On the E-M1 there is even another bonus with Zoom AF compared to the E-M5: It now features another AF frame *within* the fullscreen zoomed area, even at 14x magnification. This AF frame is smaller any other AF frame chosen by other means.

Take another look at 7:10. Normal refresh-rate does considerable hunting at all exposure settings, then I switch to high refresh-rate and the hunting stops completely! This is rather unusual, as normally you just get faster hunting, but obviously it can happen even with the same target area and camera settings.

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