Sony FX3 -vs- a7S III Comparison

Sony FX3 -vs- a7S III Comparison

Sony FX3 and a7S III both feature the same 2nd generation 12MP Full-Frame Exmor R BSI CMOS sensor, dual BIONZ XR image processors, 759-Point Fast Hybrid AF, UHD 4K 120p video recording, 10-Bit 4:2:2 Internal, 16-Bit Raw Output, HLG, S-Log2 & S-Log3 gammas, 5-axis IBIS, Dual CFexpress Type A/SD slots, full-size HDMI ports and fully-articulating LCD – so how do they differ?

Physical Differences:

The most obvious difference between the two cameras is that Sony a7S III has a 9.44m-dot QXGA OLED Tru-Finder EVF. FX3 does not.

FX3 features the same gun-metal gray body color found on Sony FX6 & FX9. Sony a7S III comes in any color you want as long as you want black.


FX3 has a lower profile that’s just 77.8 mm high compared to the 96.9 mm height of a7S III. However due to the active cooling fan, FX3 is slightly thicker at 84.5 mm vs 69.7 mm. Difference in the width of the two cameras is negligible at under one millimeter.

Sony FX3 -vs- a7S III side-by-side comparison


At 640 grams, FX3 is 4.2% heavier than a7S III which tips the scale at 614 grams.

Active Cooling:

Both FX3 and a7S III feature a passive heat sink to keep the sensor cool during filming – however FX3 takes it up a level with an active cooling fan that allows unlimited recording.

Mounting Points:

Sony FX3 top plate mounting points
FX3 is essentially a cage-free camera featuring three 1/4-20 UNC mounting holes on top along with one on each side. Both cameras include a standard 1/4-20 tripod mounting screw hole on the baseplate.

Picture Profiles:

FX3 adds the S-Cinetone picture profile to S-Log2, S-Log3, HLG profiles fround on both cameras. S-Cinetone is added to a7S III via the latest firmware update 2.00.

Zoom Rocker:

FX3 features a zoom rocker lever to control power zoom lenses with your right index finger. If you own a power zoom lens – you’ll love this. If not you no doubt will wish Sony used the standard On/Off switch in this location.

XLR Inputs:

FX3 features 4 Channel XLR Inputs in the included handle. A7S III has no internal XLR Inputs – but they can be added via the Sony XLR-K3M Dual-Channel Digital XLR Audio Adapter Kit

Top Handle:

Sony FX3 Top Handle
FX3 comes supplied with a locking top handle that transfers the audio connections from the multi-interface shoe to the XLR connections atop the handle. If no accessory mics are plugged into the XLR ports, Handle Audio can be turned off and the camera with use in-body audio.

Tally Lamps:

Sony FX3 Tally Lamps
FX3 features Front, Top, Rear Tally Lamps that glow red when the camera is rolling. A7S III does not.

Battery Life:

FX3 offers 60% longer run-time from the same NP-FZ100 Rechargeable Lithium-Ion Battery.

USB-PD Power Option:

FX3 includes a new USB-PD external power option for unlimited recording if coupled with hot-swapping memory cards.


Camera Sony FX3 Sony a7S III
Dimensions (W x H x D) 129.7 x 77.8 x 84.5 mm 128.9 x 96.9 x 69.7 mm
Weight 640 g (Body Only) 614 g (Body Only)
Viewfinder Specs None 9.44m-dot QXGA OLED
Picture Profiles S-Cinetone, S-Log2/3, HLG S-Cinetone, S-Log2/3, HLG*
Zoom Rocker Yes None
Active Cooling Internal Fan/td> None
4 Channel XLR Inputs Yes None
Tally Lamp Front, Top, Rear None
Mounting Screw Points 1/4-20 UNC x 5 1/4-20 Tripod screw only
Top Handle Included None
USB-PD Power Option Yes None
Price (USD) $3,898 $3,498

* Requires firmware update 2.00


FX3 will set your wallet back $400 more than a7S III

Bottom Line:

Sony FX3 is the perfect compact B-camera to compliment VENICE, FX9, or FX6 cinema cameras. However if you prefer the form factor of Sony mirrorless cameras with an EVF then a7S III is still the perfect choice.

Order Sony FX3 Cinema Camera from B&H Photo | Adorama | Sony
Order Sony a7S III from B&H Photo | Amazon | Sony

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