Sony Alpha a7S III Mirrorless Digital Camera Body

The Sony Alpha a7S III Mirrorless Digital Camera Body features optimizes video, sensitivity and speed, and raises the bar for what a full-frame mirrorless camera is capable of. A revised 12.1MP Exmor R BSI CMOS sensor and updated BIONZ XR image processor offer faster performance, improved noise reduction, and a wider dynamic range, along with UHD 4K 120p video recording and internal 10-bit 4:2:2 sampling.

The updated sensor design of the Sony A7SIII also brings improved autofocus performance via 759 phase-detection points, which offer intelligent subject tracking and Real-time Eye AF to ensure critical focus on moving subjects in all recording modes. The sensor and BIONZ XR processor also facilitate impressive sensitivity, with an expanded range from ISO 40-409600, as well as fast 10 fps continuous shooting for up to 1000 consecutive raw frames. Additionally, 5-axis SteadyShot INSIDE sensor-shift image stabilization is available, too, which minimizes the appearance of camera shake by up to 5.5 stops.

Complementing the imaging assets, Sony has also made some changes to the a7S III's physical design, including a rear LCD with a side-open articulating design and an impressive 9.44m-dot OLED electronic viewfinder. The camera's menu system has also been updated for more intuitive navigation and the body design helps to promote better heat dissipation for improved continuous recording capabilities. Additionally, dual memory card slots both support working with CFexpress Type A or SD UHS-II memory cards for flexible and high-speed file storage.

Body Design and Connectivity

Video is the primary application of the a7S III, and improvements to the sensor and processor enable faster readout speeds and greatly reduced rolling shutter, along with high-bitrate internal recording, 16-bit raw output via the full-size HDMI port, and flexible control over motion with variable frame rate selection. The a7S III also does away with recording time limits and incorporates HLG for direct HDR production as well as S-Log2/S-Log3 gamma profiles for advanced HDR production with editing.

At the heart of the new Sony Alpha III is a 12 megapixel full-frame sensor that has been improved compared to the Alpha 7S II. Sony is now opting for a construction with back exposure (BSI), with which more light can be captured and which enables better results with low light shots. The maximum sensitivity is still ISO 409.600 (expandable down to up to ISO 40). The sensor is supported by the new BIONZ-XR processor, which is said to have eight times as much computing power as the previous image processor. Sony is also breaking new ground in operation: For the first time in the Alpha 7 series, a fully moveable monitor (3.0 inches, 1.44 million points) was installed, which now also allows touch operation of the menus. The structure of the menus has also been completely revised; among other things, only the relevant entries are available in photo and video mode for better clarity. The OLED viewfinder achieves a record resolution of 9.44 million points and a magnification of 0.9x. Even glasses wearers have the entire picture in view, the size of the picture can also be reduced.

Sony A7sIII specs:

• New 12MP sensor with fast readout and S-Cinetone colorscience
• records FHD 240fps, 4k120fps 10bit 4:2:2 and 4K120fps raw over HDMI
• ONLY Up to 4k60 will be 10bit 4:2:2 internal.
• Downsampled 1080p from 4K, making this the best 1080p hybrid ever made! No line skipping or pixel binning.
• No internal RAW.
• 600mbps bitrate
• Base ISO 160 for S-LOG3
• no Dual ISO
• Max ISO 409600 (video)
• 16bit RAW output
• Sony claims 15 stops dynamic range
• Movie Edit add-on compatibility for Image Stabilization in post
• world’s highest resolution new 9.44 million dot EVF (QXGA resolution)
• same Sony A7rIV AF system
• new kind of passive (noise free) cooling system
• no overheating, no recording time limits (They are claiming to not have overheating issues for at least 1hr even at the highest framerate.)
• UHSII card and CFexpress Type A card support (each of th two slots takes them both!)
• Looks pretty similar to a Sony A7rIV.
• fully articulating screen like the one used by the Sony ZV-1.
• The video record button is now on the top of the camera, placed behind the shutter button

4K with 120p
One focus of the camera is video recording. Unlike Canon with the EOS R5, Sony does not use 8K for video, but continues to use 4K, which is said to achieve the best results so far with an alpha camera. The sensor’s 12 MP resolution enables a full-pixel readout without pixel binning and without crop up to 4K / 60p. In this setting, the recording limit should be one hour without overheating – the EOS R5 only manages 30 minutes at 4K / 60p. The video recording of the Alpha 7S III in 4K / 120p mode is limited to this length – by the way, a slight crop is used (1.1x).SonyAlpha

With Full HD, the Alpha 7S III even records at up to 240p. For time-lapse recordings, lower frame rates up to 1p can also be selected in S&Q mode. It is recorded internally with a color subsampling of 4: 2: 2 and a color depth of 10 bits. New codecs are available: XAVC-S-I records single images (All-I) with a data rate of up to 500 Mbits / s, XAVC-HS reduces the amount of data in image group compression to 200 Mbit / s thanks to H.265 compression. With HDMI 2.1, the camera can even output 4K / 60p as 16-bit raw files (ProRes Raw) to an Atomos recorder. Of course there is also a logarithmic gamma profile available (S-Log 2/3), which should enable a dynamic range of over 15 f-stops; the sensitivity starts here at ISO 640 (extended: ISO 160). According to Sony, the rolling shutter effect has been significantly minimized. The Alpha 7S III is equipped with a 5-axis image stabilizer in the housing, which, measured according to the CIPA standard, achieves an effectiveness of 5.5 f-stops; In video mode, digital stabilization (active mode) is also used, which also uses a gyro sensor. The information from this gyro sensor can also be stored in the metadata of the videos so that it can be used in post-processing for digital stabilization.

Fast autofocus and 10 frames/s
The hybrid autofocus covers 92% of the image sensor and uses 759 phase detection points and 425 with contrast AF. In addition to human, the AF algorithms now also recognize animal eyes – according to Sony, also at a greater distance than before. The AF sensitivity goes down to -6 EV series, the camera shoots at up to 10 frames / s. The mechanical shutter is designed for 1/8000 s.

Sony is using two memory card drives in the Alpha 7S III for the first time, which can use both SD cards (UHS-II) and the new CFexpress type A cards. They are smaller than Type B cards and faster than SD cards. For most video modes, SD cards of video classes V60 and V90 are sufficient; CFexpress is only required in S&Q mode with 4: 2: 2 color subsampling and 10 bit color depth. The series mode also benefits from the faster cards; 1000 uncompressed raws in a row should be possible here