When comparing Olympus OM-D E-M1 vs Sony a7R II, the Slant community recommends Olympus OM-D E-M1 for most people. In the question“What are the best mirrorless cameras?” Olympus OM-D E-M1 is ranked 1st while Sony a7R II is ranked 3rd.
Ranked in these QuestionsQuestion Ranking
Pro Amazing image stabilization
Pro Supports standard Four Thirds lenses
Built-in phase detection allows you to use standard Four Thirds lenses via an adaptor.
Pro Good electric viewfinder
The viewfinder is bright and sharp.
Pro Great focusing system
The focusing system is quick, it rarely if ever resorts to focus hunting and it's consistently accurate.
Pro In-body stabilization saves money on lenses
Since stabilization can be applied to any lense, you can save money by not having to spend it on stabilized lenses which are generally more expensive than non-stabilized lenses.
Pro Convenient in-camera RAW conversion
Pro Quick access to settings
The camera takes a "buttons and dials for everything" approach. It's also possible to change what some of the buttons do.
Pro Great image quality
E-M1 takes sharp 16MP images with tonal colors. There's little noise up until 1250 ISO and there's little smudging up until 6400 ISO.
Pro Continuous autofocus works well at a distance
Continuous autofocus is reasonably reliable using long lenses at a distance. It works slightly better with the subject coming closer/moving away from the camera than it does when the subject is moving from side to side.
Pro Can preview HDR images in viewfinder
HDR images can be composited in-camera and the output seen using the viewfinder.
Pro MFT lens mount allows for a wide variety of lenses to choose from
Micro Four Thirds system is a standard used by Panasonic, Olympus, Sigma and many others so you're not locked into a having to buy lenses from one manufacturer.
Pro Excellent image quality
The camera has a 42MP BSI-CMOS sensor. Both in good light and low light, whether you're shooting in RAW or JPEG, the images have excellent detail. You can check out detailed studio tests over at DPReview.
Pro Great Auto ISO implementation
Pro In-body image stabilization
Pro Good 4K video
The camera can capture 4K30 (at up to 100Mbps), 1080p60 and 720p120 video internally and save to XAVC S with S-Log2 color profile. The video is detailed with little noise both in good light and in low light.
It's worth noting that 4K video is slightly better when shooting using the Super 35 region of the sensor instead of the full sensor region while 1080p performs better when shot at full width of the sensor and downsampled.
Pro The camera can be used while it's charging over USB
Pro Good AF for video
Camera's autofocus is fast and decisive. And it allows a good degree of control over how it behaves. You can adjust the focusing speed as well as sensitivity.
Pro Face detection AF for video
Pro Good video shooting tools
The camera has a zebra and focus peaking tools allowing you to monitor focus and exposure while shooting.
Pro Flat color profile for video
Pro Has a completely silent mode
If set up to use electronic shutter, the camera makes zero noise.
Pro Excellent AF point coverage
399 phase-detect AF points and additional 25 contrast-detect AF points.
Pro Excellent continuous AF
Both in good light and in low light.
Pro Good noise reduction control
Pro Flat color profile available for increased dynamic range
A flat color profile captures footage in low contrast and higher dynamic range allowing for easier color grading in post-production.
Pro Great dynamic range
Pro Excellent low-light capabilities
The camera has class-leading high ISO capabilities. A look at real-world high ISO shots can be found here.
Con Video quality could be better
The video is limited to 24MBit max bitrate.
Con Limited framerate options
Shooting in 1080p the camera is limited to 30fps, there are no slow-mo options or 24fps options.
Con Continuous autofocus is spotty at close range
Continuous autofocus is sometimes seen hunting with wide angle lenses at short range.
Con Power switch placement can feel inconvenient
Con Somewhat unintutive RAW conversion interface
Con The depth of interface options can be overwhelming at first
Con Cumbersome menu system
The camera has a plethora of poorly organized menu items.
Con Continuous shooting is limited to 5fps
With 5 frames per second the camera lags behind other cameras. If you're looking to shoot sports, this camera might not be the best choice.
Con Limited selection of native lenses
Sony has a comparatively little selection of lenses and while you can add an adapter to use lenses from other manufacturers, that choice comes at the expense of some functionality.
Con Screen is not touch sensitive
Switching AF points could be simplified by having a touchscreen.