see also:

• Sony a7R IV
• Olympus OM-D E-M1 Mark III

• the Sony a7RIV is an expensive 61mp full frame mirrorless camera which is a similar size and ergonomics to the 20mp Olympus OM-D E-M1 Mark III Micro Four Thirds mirrorless camera but which can do 24mp APS-C or 15mp 2x crop post-processed
• what would it take for the Sony to replace the functionality of the Olympus camera?

• cost
  • $US1799
• 20mp 2x crop of full frame for greater telephoto reach
  • the Sony can do in-camera APS-C crop to reduce file size, but a 2x crop needs to be post-processed and will only be 15mp
• minimal rolling shutter of the sensor which allows the silent electronic shutter to be far more usable
  • much reduced motion artefacts which makes:
    • the faster burst speeds usable for:
      • sports
      • ProCapture
      • motion freeze
      • Live ND filter effect mode
      • hand held 50mp HiRes mode with less moire
    • usable 1/32,000th sec electronic shutter speed (the Sony can only do 1/8000th sec mechanical)
    • far better video quality although clip files are limited duration due to the 4Gb file limit
  • faster flash sync speed for silent shutter
• incredible IPX1-rated weather-sealing which gives more confidence in inclement weather
• fast burst mode:
  • the Olympus can do 10fps with C-AF and 15fps S-AF with mechanical shutter and 18fps C-AF and 60fps S-AF with the electronic shutter
  • the Sony can only do 10fps mechanical shutter in 12bit compressed RAW or APS-C and only 6fps in uncompressed 14-bit RAW
• 7.5EV image stabilisation with OIS lenses
  • the Sony can only do 5.5EV
  • the E-M1 III is the best camera out there for handheld video such as vlogging whilst walking
• fully articulating swivel rear LCD
  • the Sony's can only tilt, so no selfie mode, no way to protect it by rotating it inwards
• Starry Sky AF mode
• Live Composite night mode
• Live BULB/Timed night modes
• automatic in-camera focus stacking
• in-camera programmable focus range
  • this provides a mechanism to force AF to ignore foreground and background areas with any MFT AF lens
• Eye AF prioritisation of the closest eye
• easier to use menu system

• Olympus mZD 40-150mm f/2.8 pro lens
  • “entry level” Sony FE 70-300mm f/4.5-5.6 G OSS
    • same FOV range similar DOF at FF
    • similar weight, same filter thread but shorter although extends on zooming whereas the Olympus doesn't
    • close focus 0.9m not 0.7m as with the Olympus
    • does have the benefit of becoming 100-450mm in APS-C mode but optical quality may not be high enough to provide this detail.
  • Sigma 100-400mm f/5-6.3 OIS
    • coming late 2020
  • Sony FE 100-400mm f/4.5-5.6 GM OSS lens
    • almost twice as heavy and twice as expensive
• Panasonic Leica DG Elmarit 200mm F2.8 Power OIS lens
  • this approximately equates to 400mm f/5.6 lens on FF or 300mm f/4 lens on APS-C crop mode - Sony do not make any primes in these categories - you could use a Canon EF lens but AF would not quite be as fast and they are unlikely to be sharp enough for the a7RIV's sensor being designed for older lower resolution work
  • OIS cannot be used in dual sync IS on Olympus cameras
  • $US2999 including bundled DMW-TC14 1.4x teleconverter
  • Sony FE 100-400mm f/4.5-5.6 GM OSS lens
    • this will essentially cover this lens but optics may not quite be as good as the Leica
    • it is longer - 205mm and extends on zooming while the Leica is only 174mm
      • this lens is similar design to the old Olympus ZD 50-200mm f/2.8-3.5 lens for Four Thirds but on steroids - significantly longer and heavier and with extra function switches and buttons, plus an effectively wider aperture, and thus no where near as discrete as the Leica, especially so being a white lens
    • it is heavier at over 1.3kg compared to 1.2kg for the Leica
    • close focus is better at 0.98m not 1.15m as for the Leica
    • bokeh is unlikely to be as nice given the zoom elements
    • $US2499 + $US548 for the 1.4x teleconverter puts them at the same price
• Olympus mZD 300mm f/4 PRO lens
  • this approximately equates to 600mm f/8 on FF or 450mm f/6 on APS-C crop mode
  • Sony FE 200-600mm f/5.6-6.3 G OSS
    • unfortunately there appears to be AF issues with this lens on the a7RIV when used on fast moving subjects or when panning
    • $US1999 making it cheaper than the Oly which is $US2499
    • close focus 2.4m which is much worse than the Oly's 1.4m
    • it is almost twice as heavy at 2115g compared to 1270g for the Oly
    • around 50% longer at 318mm compared to the Oly's 227mm
    • will it match the sharpness and bokeh of the Oly?
    • but is more versatile, gives more reach
  • Canon EF 400mm f/5.6L
    • this in theory would almost match it in APS-C mode but this lens cannot resolve to the a7RIV's sensor to keep up with the optical quality of the Olympus lens, plus it is not weathersealed and AF is likely to be much slower
    • if Sony made a native GM lens of this size then it would be a better match
  • Canon EF 100-400mm f/4.5-5.6L IS II USM
    • a much better lens optically than the 1993 era designed Canon EF 400mm f/5.6L and in theory would almost match the Oly lens for telephoto reach when used in APS-C mode
    • $US2199 so similarly priced and more versatile but AF would be slower and it is heavier at 1.6kg and OIS is only 4EV
• Olympus 150-400mm f4.5 pro zoom with built-in 1.25x TC
  • due to be released late 2020
  • this approximately equates to 300-800mm f/9 on FF or 200-530mm f/6 on APS-C crop mode
  • with the in-built 1.25x TC activated this approximately equates to 380-1000mm f/11 on FF or 250-670mm f/7.3 on APS-C crop mode
  • Sony FE 200-600mm f/5.6-6.3 G OSS with a 1.4x or 2x TC
    • 1.4x TC gives 280-840mm f/8-f/9 on FF
    • 2x TC gives 400-1200mm f/11-f/12.6 on FF
    • we will have to see how the image quality compares but it is unlikely this G entry level zoom will have optics to match the a7RIV resolution when mated with teleconverters
  • Sony FE 600mm f/4 GM OSS with a 1.4x or 2x TC
    • this would match it optically but is incredibly expensive at over $US12,999 with TCs and is 3kg
    • obviously has a massive advantage of 600mm with f/4 DOF and the 61mp FF sensor with higher ISO performance
  • Canon EF 200-400mm f/4 with in-built 1.4x TC plus an extra 1.4x TC
    • in FF this gives 200-400mm f/4 switchable to 280-560mm f/5.6 with in built TC
    • using an extra 1.4x TC would give 390-784mm f/8 which gets you to the same ball park as the Oly natively but the Oly can then kick in its TC to take you further, while the a7RIV gets to go to APS-C mode to match.
    • 3.6kg and $US11,800 are likely to be show stoppers though plus AF not as good as a native Sony FE lens.