Autofocus and Manual Focus Performance
Compared to the E-M5, the E-M1 has a “Dual Fast AF” system that can utilize both contrast and phase detection autofocus. In Single AF mode, the camera by default uses contrast-detection AF mode, unless you mount an older Four Thirds lens, in which case the camera will automatically switch to phase-detection AF. So phase detection is not used when shooting with Micro Four Thirds lenses in Single AF mode. You might find this disappointing, as traditionally phase detection is faster than contrast detection, especially on DSLRs. However, that’s really not the case with Olympus – contrast-detection AF is very fast and accurate. Having shot with pretty much every mirrorless system on the market, I would say that the contrast-detection AF system on Micro Four Thirds is still the fastest. Other systems are slowly catching up, although that’s mostly true for bright daylight conditions, where they switch to phase detection autofocus.
So when is phase-detection AF used then? With Micro Four Thirds lenses, that functionality is exclusively reserved for Continuous AF mode. When you switch to continuous AF, the camera uses a combination of both contrast and phase-detection AF, which results in fast focus acquisition and less “probing” of focus. This is great news for those that want to shoot moving subjects and have the camera continuously track the subject(s). Aside from the Nikon 1 system, I have been criticizing all mirrorless systems for their poor Continuous AF performance. While they do a pretty good job in Single AF mode, tracking subjects continuously has been problematic, even for the Micro Four Thirds system. When using the Olympus OM-D E-M5, for example, I found continuous AF to be too slow and inaccurate, making it rather useless for shooting fast action. My biggest frustration was the continuous “probing”, which was just rather annoying to use.
Since contrast-detection AF needs to scan for focus continuously when tracking, I understand that it is considered to be normal behavior. However, if you compare this behavior to a DSLR that uses phase detection, the experience is totally different. Olympus engineers realized that they had to move away from just contrast-detect AF and implement phase-detection AF for continuous focusing, which was a very smart move. Indeed, the OM-D E-M1 does focus much better in continuous AF mode than all other Olympus Micro Four Thirds cameras, including the E-M5. When phase detection is engaged, the camera locks on pretty well on high contrast subjects, even in low light conditions. When focusing on low contrast subjects, however, the camera might attempt to re-acquire focus and might even hunt for focus, which is quite normal and happens on DSLRs as well. While the “probing” of autofocus is greatly reduced, the camera sometimes still does it, probably when switching to contrast-detection AF.
To summarize the Continuous AF behavior, I would say that it has certainly greatly improved over what it used to be, but it is still not close to what a DSLR can do. I photographed my kids running around with the E-M1 in Continuous AF and the camera generally did well, but I still had plenty of blurry photos. The Fuji X-T1 was similar in this regard – it was a world better in comparison to previous Fuji cameras, but still not very reliable. For slower moving subjects, both the E-M1 and the X-T1 seemed to do pretty well with a good number of in-focus shots.
If you want to be in full control of focusing, have superb precision, but at a cost of slower focusing, you might want to switch to manual focus. Olympus has finally implemented the much-needed focus peaking feature on the E-M1, making manual focus a breeze to use. In combination with the ability to zoom from 5x to 14x magnification (which must be turned on in Custom Menu->AF/MF->MF Assist->Magnify->On) when you touch the focus ring, focus peaking can be really powerful when focusing. Whatever comes into focus gets highlighted with white borders, so you can focus with superb precision – something you would never be able to do with a DSLR, unless you switched to Live View and zoomed in. When zoomed in, you can rotate the rear dial to switch between different zoom levels.
Metering is generally pretty good and nothing to complain about. The E-M1 seems to be accurate in most situations, similar to what I get from my DSLR cameras. If you shoot in high contrast situations, such as when shooting directly at the sun, exposure might vary and images might come out either over-exposed or under-exposed. The good news is, compensating in such situations is really simple and straightforward – just rotate the front dial of the camera and you will be good to go. It also really helps to have -5 to +5 compensation range when shooting in extreme situations.
Despite its smaller sensor (when compared to APS-C), the Olympus OM-D E-M1 seems to have good dynamic range. According to DxOMark, the E-M1 has a better dynamic range at 12.7 EVs than its predecessor, the E-M5 at 12.3 EVs. This is worse than what we would see from an APS-C camera like Sony A6000, but not by a huge margin, as shown on the below screenshot:
As with all digital cameras, increasing camera ISO also decreases dynamic range, so shoot at base ISO of 200 if you want to preserve the most amount of information on your photographs.
Let’s see how the camera does in ISO performance against other cameras. Choose the next page below.
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