Alpha a7S II

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Sony A7S III Frequently Asked Questions

The Sony Alpha A7S III camera is a revolutionary update to the venerably A7S II low light camera.  Sony really went all out on the features for this camera, updating and improving pretty much every aspect of its predecessor, while maintaining and exceeding the low light performance that made the A7S II one of the most successful mirrorless cameras ever.

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What are the differences between the A7S III and the A7S II?

The list of differences is almost as long as the list of specifications.  Almost every single thing about the A7S III is new.  New sensor, new battery, new screen, new body, new EVF, new menus, new recording options.  About the only thing that hasn’t changed is the resolution of the sensor.

What are the differences between the A7S III and other A7 cameras?

The three big differences between the A7S III and other 3rd and 4th generation A7 cameras are resolution, color science, and recording options.  The A7S III has a low-resolution sensor when compared to other A7 cameras, coming in at 12.1 MP compared to 24.2 MP on the A73 or 61 MP on the A7R4.  The color science has been updated based on the VENICE and FX9 colors.  The big change however is in the recording options.  The A7S3 has multiple options for recording 10-bit 4:2:2 in any resolution or frame rate, up to and including 4k at 120p.

Does the A7S III have Dual Native ISO?

Probably not in the same sense that the FX9 and VENICE cameras have Dual Native ISO.  Read more about how those cameras achieve Dual Native ISO here.  Early access users did notice that there seemed to be a second “native” iso at about 16000 where the noise floor was noticeably cleaner.  This has been borne out in testing by Cinema5D, although users with full production models notice the change at around 12800.  Most likely what is happening is that there is a second analog to digital converter that kicks in to handle the extra noise of the higher ISO values. To read more about Dual Native ISO check out the blog post from Z Systems own Keith Mullin here.

What Codecs does the A7S III record?

The A7S III has 3 codec options available.  XAVC S, XAVC SI, and XAVC HS.  XAVC S is a Long-GOP h.264 codec, XAVC SI is an All-I h.264 codec, and XAVC HS is a Long-GOP h.265 Codec.

What is h.265?

h.265 is a new and more efficient way of encoding video that yields higher image quality at lower data rates than h.264 codecs.

What media does the A7S III use?

The A7S III has 2 card slots that can both take either SDXC or CF Express Type A cards.  CF Express Type A cards are capable of recording in any combination of codec and frame rate.  SDXC UHS-II V90 cards can record anything except for 4k 120p XAVC SI codec.

How long can I record on my cards?

There are a ton of different Codec, Frame Rate, and Bit Rate options to choose from with the A7S III. To give you a basic idea of recording times I went with the bets Bit Rate option in each of the different codecs and broke it apart by frame rates. I used a 64GB SD card and an 80GB CF Express Type A card for the recording times.

CodecBit RateFPSMb/s64 GB80 GB
XAVC S10-Bit 4:2:224fps100Mb/s85min106min
XAVC SI10-Bit 4:2:224fps240Mb/s35min44min
XAVC HS10-Bit 4:2:224fps100Mb/s85min106min
S&Q Mode
XAVC S10-Bit 4:2:2120fps
24 base
XAVC SI10-Bit 4:2:2120fps
24 base
60 base
XAVC HS10-Bit 4:2:2120fps
24 base

Can I record RAW?

Not internally, but you can output a RAW signal from the full-size HDMI port to an external recorder.  At this time only the Atomos Ninja V recorder is capable of reading this signal.

What improvements have been made to the sensor?

The sensor has been improved in quite a few ways.  It is a completely new 12.1 megapixel sensor with Back Side Illumination architecture for even better low light performance than the A7S II.  It has also been paired with a new processor for faster read times, greatly reducing the amount of rolling shutter. Check out the tests done by Cinema 5D regarding sensitivity, dynamic range, and rolling shutter here. Be aware that the way Cinema 5D measures dynamic range is not the way any manufacturer measures so their stated tested dynamic range and that of Sony will be different.

What is the dynamic range?

The A7S III has 14 stops of dynamic range in still photography mode, and 15 stops in video mode using SLog3.

How high can I push the ISO?

It’s not really clear yet how high you can push the ISO without needing to add noise reduction in post to achieve usable footage, but early users were easily doing 12,800 or 16,000 ISO without degrading the image too much.

What color science is on the camera?

The out of the box color science is based on that of the FX9 and S-Cinetone.  The camera also retains S-Log3 and SGamut3.Cine gamma and gamut options.

Does the A7S III have LUTS?

No, the A7S III uses a built-in “Gamma Display Assist” for monitoring log signals.  It is a very basic transform from Log to a viewable format.

What is hybrid AF?

Hybrid AF on the A7S III utilizes 2 different kinds of autofocus points on the sensor (Phase detection for speed and contract detection for accuracy). This means that the camera has not only fast but also accurate autofocus that can lock on to subjects, detect faces and eyes as critical focus elements, and the Hybrid AF is also customizable, allowing for adjustment of AF transition speed and subject shift sensitivity.

What kind of image stabilization does it have?

The A7S III can make use of 3 different stabilization elements.  If the lens attached has optical stabilization (OSS) the camera will use that in addition to any other stabilization.  The camera body itself has In Body Image Stabilization (IBIS) meaning that the sensor itself is on a 5-axis gimbal adding stabilization to any lens.  Lastly, if you are using a Sony lens with the camera you can use something called Active Stabilization.

What is Active Stabilization?

Active stabilization is an electronic stabilization applied in-camera that uses the accelerometers and gyros in the camera to adjust the image for stability before recording.  It does require you to use Sony native lenses and will crop in the image a small amount to give the image a bit of a buffer around the outside for stabilizing.