The new Sony a7III compared to the Sony a7RIII and Sony a9

Written by Gary on March 2nd, 2018

Sony has just announced a brilliant new full frame mirrorless camera – the Sony a7III which is a massive upgrade to the earlier a7II model and is a cross between a budget-level version of the Sony a9 and the high resolution Sony a7RIII, both of which are much more expensive.

All of these cameras are roughly the same size and weight (around 670g) and all are partly weathersealed – recent tests show the a7RIII is not sealed on the bottom so don’t let water pool under it!

All of these have a 5 axis sensor based image stabilisation system, although this has been significantly improved in the newer models.

All have the same flash sync of 1/250th sec and the proprietary modernised Sony flash hotshoe.

The feature set of the new Sony a7III make it almost perfect for wedding photographers as it gives sufficient image quality, the full frame shallow depth of field capabilities, class leading Eye AF capability and AF region coverage (far better than any dSLR), and very good high ISO performance, while the addition of the 2nd SD card slot provides professionals with their much desired image backup system in case of card failure, and very good video performance.

Compared to the Sony a7RIII, the a7II is much more affordable, has better AF coverage, slightly better burst performance but the compromise is 24mp instead of 42mp, a lower resolution EVF, and no pixel shift mode.


It is likely they will all suffer the same star eating noise reduction issues, so Milky Way fans need to assess this issue.

As usual, the links below take you to my wikipedia pages where you can get more information and links.

Quick comparison of Sony cameras:

Sony a7II Sony a7III Sony a7RIII Sony a9
Price $AU1795 $US1999 / $AU2999 $US3499 / $AU4899 $US4500 / $AU6745
Sensor 24mp 24mp 42mp 24mp
Sensor 24mp 24mp 42mp 24mp
dynamic range ISO 100  13.9EV  13.8EV (12.4EV uncompressed RAW in burst mode – 12bit)  14EV  12.6EV
dynamic range ISO 640  11.8EV  13.4EV due to dual gain design  13.1EV due to dual gain design  12.4EV
AF 25CDAF, 117PDAF (all clustered in central area), some EyeAF, AF only half as fast as the others and C-AF is problematic 425CDAF, 693PDAF, 93% coverage, superb EyeAF in C-AF 425CDAF, 399PDAF, 68% coverage, great EyeAF in C-AF 425CDAF, 693PDAF, 93% coverage, superb EyeAF in C-AF
comments older battery, poor battery life; no 4K video; 1080HD only to 60p 50Mbps; only USB 2.0 not USB-C; IBIS not as good; no electronic silent mode; high ISO not as good; LCD screen not touch sensitive; EVF not as good; only one SD card slot; older styling and menu system; joystick; AF in magnified focus mode; touch AF; AF-On button; 2.3mdot EVF; USB-C 3.1; red night mode; Pixel shift mode; 3.7mdot EVF; 4K video; 1080HD 120p 100mbps; USB 3.1; touch screen only selects AF point; 3.7mdot EVF; best sports functions; joystick; 4K video; 1080HD 120p 100mbps; AF-On button; “AF Area Registration”, dynamic range not as good as a7RII;

It would appear this is a fantastic upgrade to the Sony a7II and at that price point with its feature set should be a very popular camera indeed and should cover most needs.

It beats the Micro Four Thirds cameras such as the Olympus OM-D E-M1 Mark II and the Panasonic G9 on some features (Eye AF, AF coverage, full frame IQ and shallow DOF capability, and EVF), but the Micro Four Thirds cameras beat it in terms of burst rate (the Olympus can get to 18fps and even 60fps), feature set (eg. Pro Capture mode, HiRes mode, Live Composite, etc) , image stabilisation, swivel screen, and most importantly, weight, size and price of the lenses.

A quick comparison of Sony lenses vs Micro Four Thirds lenses:

Sony FE 24-105mm f/4G OSS:

  • this is $AU2029 and weighs 663g, uses a large 77mm filter
  • the Olympus 12-40mm f/2.8 doesn’t give as much reach and loses 1EV in shallow DOF but comes in at $AU798, uses 62mm filters and weighs almost half as much at 382g

Sony FE 12-24mm f/4 G:

  • this is $AU2598 and weighs 565g
  • the Olympus 7-14mm f/2.8 comes in at $AU1394, and weighs slightly less

Sony FE PZ 28-135mm F/4 G OSS

  • this is $AU3068 and weighs 1215g, but to be fair, it is built as a Cine lens
  • the Olympus 12-100mm f/4 OIS is $AU1540 and is 561g and gives much more reach of 200mm in full frame terms, making it a great travel lens, but loses 2EV of shallow DOF capability, however, at half the weight and price this may not be a bad compromise for most people who can resort to prime lenses for shallower DOF if needed.

Sony FE 100-400mm f/4.5-5.6 GM OSS lens

  • this is $AU3648, weighs 1395g
  • the Olympus 40-150mm f/2.8 is less than half the price and weight but only gets to 300mm not 400mm
  • the Panasonic 50-200mm f/2.8-4.0 OIS is less than half the price and weight

Sony FE 85mm f/1.4 G

  • this is $AU2799 and weighs 820g, and is perhaps the most important lens to match with the a7III’s Eye AF capability
  • the Olympus 45mm f/1.2 is $AU1588 and weighs half as much at 410g but you do lose 1.5EV in shallow DOF capability, although, for most situations, the shallow DOF of the Olympus lens suffices and is perfect for head and shoulder portraits. Whilst the Sony has the better tracking of subject’s eye, the Olympus is probably better at selecting the all important closest eye.

And there is nothing yet to match the Olympus 300mm f/4 with its 600mm full frame reach, although Sony appears to be working on a lens with that reach, but one can expect it will be 2-4x more expensive and much heavier than the Olympus lens.

If you need the features of Sony full frame and you don’t mind the weight, size and at least twice the cost of the lenses, then the Sony 7III may be the camera for you, but for most people, the Micro Four Thirds solution will be the better, more enjoyable option.


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