Sony A7S II 120fps Slow Motion Quality Tests!


The Sony A7S II had a lot to live up to considering low light performance and it has so far been exceptional. But the question about slow motion quality lingered as to a new Spec of 1080p 120fps would perform compared to the previous 720p 120fps and to regular 1080p 60 video.   New video tests have surfaced that show how good and or limited the new slow motion spec is on this camera. Many will be satisfied with just the 4k video at astounding levels of ISO which short of the Canon ME20F-SH with 4 million ISO it is the best second option with more resolution at a Max ISO of 409,600.

The Slow motion spec seems to be somewhat limited in quality compared to normal video on the Sony A7S II with a reported 20Mbit/sec for 120fps which is the 100Mbit/sec camera spec stretched 5x to playback at 24p.  20 Mbit is’t that bad considering it is 1080p and the artifacts are well controlled. There are some here and there including some compression macro-blocks if you search for them but for the vast majority of users the camera has a very good slow motion mode built in; albeit at 120fps as it will go no further up the frame rate scale.

Crop: The camera also creates a 2.2x crop on the full frame sensor to give precisely 1080p which is why artifacts are hard to come by in the way of moire and aliasing as the footage is being recorded from real pixels at 1:1 instead of downsizing or skipping lines which is a plus.  You will however loose a lot of wide angle goodness giving you a field crop a little smaller than a Micro 4/3 sensor which in itself is not too bad.


One good example is the one below and be sure to visit the youtube page here to read the full shoot explanation in the description of the video by Sami which is very good and enlightening. Be sure to check the rest of the footage samples as they have a lot of great uses for teh feature.

Sony A7S Mark II: Graded high-speed & 4K low light sample footage by Sami Saarela:

Sony A7s II : Slow Motion Test by ZurisaddaiCJR:

Sony a7s II Review Part 2 HD Slow Motion, SLog3 and 5 Axis Stabilization by BananaManaTV:

STOP THE TIME – Sony A7S II Slow Motion Test by Raphaël Gilles:

Sony Alpha a7S II / HFR, slow motion mode test by nezzeslassponteu:

SONY A7S II-S-Log3.Full HD.120P Slow Motion by LONG影音:

Sony A7sII  1080p 5x Slo-Mo Fireplace Test by Jason Tseng:

Sony Alpha A7S II FullHD Slow motion 1 by e PHOTOzine:

Wrapping it up: The takeaway from the videos is that the Sony A7S II is a great 120fps Full HD camera with low light abilities that are the best in the segment. If you need to shoot 120fps 1080p in low light environments this camera is your best option aside from higher end dedicated cameras with larger pixel sizes in the Photron or Phantom realm.

The pixel to pixel capture gives few if any artifacts besides Bayer resolution loss to the image which is a first for on the go 120fps slow motion modes in ILC cameras.  Previous attempts like on the Panasonic GH4 or the Samsung NX1 did ok but there was moire and aliasing present which here is not so when you shoot your only concern should be exposing properly and knowing the limitations of a codec that caps slow motion at 20Mbits/sec.  That said the camera brings to the table great low end slow motion as a bonus. It will not be cheap with the body at near 3k US but you are also getting a 4k camera that works at extremely high ISOs. Lots to like about the Sony A7S II and very little minuses.  It would have been great to have 240fps 1080p but you really can’t have everything.  For higher frame rates way above 120fps you will need to step up to other options like the edgertronic on our camera guide.  -HSC

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4 thoughts on “Sony A7S II 120fps Slow Motion Quality Tests!”

  1. Personally, I think this sucks because I bought the A7s because of low light Video and kept it only because it was very clean at 6400 ISO.
    Turns out the ProRes LT 4k DownRes to 1080P30 was much better than 1080P60 internal.

    I upgraded (?) to the A7sII to get 1080P120 at 100 Mbps. Not for SloMo but smooth detailed footage.
    My internal recordings are actually at only 56 Mbps.
    It is full of artifacts at ISO 6400 and unusable at the ISO 8000 needed to get nearly the same amount of light in.

    Even the 1080P60 internal at only 50 Mbps is better.
    And, it is very usable at ISO 6400

    Today I will be comparing to the A7s, both internally and externally recorded 1080P60 with an Odyssey 7Q+ and ProRes LT.
    If the A7sII is not noticeably better it will be sent back. I do not use Steady Shot on a TriPod.

    1. High speed requires extreme amounts of light to deliver clean results. The A7s II Seems to only deliver 20mbps at 120p which is quite low but should be better than most slowmo on recent cameras at that frame rate. Shoot at under 3200 ISO at 120p in well lit conditions and you should get an improvement. ISO should not be a replacement for light in a scene, it should be just a means of helping a shot where you can’t add more light. Thanks for sharing your results!

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