The Sony A7s 4K Guide (Part Eight): Post Production and Grading

In Part Seven we looked at the cost of putting together a Sony Alpha A7s kit. In this final part, we’ll study the post production options and challenges in dealing with both 1080p and 4K footage.

Premiere Pro Screenshot A7s LUT

Editing

1080p

As mentioned earlier, I would never use any codec other than XAVC. Not only is editing easier with XAVC S, it also offers the highest data rate and most robust video file to push in post production. The camera does allow dual recording, though I’m not sure why anyone would use that. Even if I wanted to create dailies on the fly, I’d prefer H.264 in 1080p.

Here’s a list of NLEs that support XAVC S, AVCHD and MP4:

  • Adobe Premiere Pro CC 7.0 onwards
  • Apple Final Cut Pro X 10.0.x via the Sony PDZK-LT2 plugin
  • Avid Media Composer 7 via the Sony PDZK-MA2 plugin
  • Grass Valley Edius Pro 7
  • Sony Vegas Pro 12
  • Autodesk Smoke 2014 onwards
  • Editshare Lightworks Pro 11

 
No matter which NLE you choose, editing Sony A7s footage is a breeze. You will never need more than one hard drive (no need for RAID 0) for real-time playback. Even a portable 2.5″ platter drive via USB 3.0 delivers 65 MB/s or about 10 streams of 50 Mbps XAVC in 1080p.

4K

As far as 4K is concerned, the story is different. Prores HQ 4K runs about 110 MB/s. Even a fast 7,200 rpm drive will suffer when you add titles, grades, etc. Therefore, real-time editing and playback demands RAID 0 (at least 3-4 drives) or an SSD via USB 3.0 or Thunderbolt.

  • If you’re shooting a 5 minute project with a shooting ratio of 20:1, you’ll have 100 minutes of footage, or 660 GB.
  • If you’re shooting a 90 minute movie with a shooting ratio of 10:1, you’ll have 6 TB of footage.
  • If it’s a documentary with a larger shooting ratio, you’ll need tons of drives. Here, it might be a good idea to use another codec for acquisition, maybe XAVC (it supports 4K).

 
Prores HQ is good enough for any kind of editing project, even cinema.

The ‘complication’ in the editing workflow for the Sony Alpha A7s comes in the grading. Let’s look at that next.

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Grading S-Log2

To truly understand S-Log2, you’ll need to read my notes from Part Five and understand the fundamental differences between:

 
If you don’t want to take the trouble, then don’t buy the Sony A7s or don’t record in S-Log2.

Grading S-Log2 is pretty easy and fun. The footage holds up well “under limits”. I have not had any banding or posterization. However, the nature of the S-Log2 curve brings two challenges you need to be aware of:

  • Strict highlights that must be controlled during exposure
  • Shadow noise

 
The second is very telling. Cameras like the Sony F55/F5 using S-Log2 have very clean shadows. So does the A7s in stills mode. However, in all the footage I’ve seen so far, either the restricted gamut of the sensor or the heavily compressed codec (including color compression) really gives you a small window in the shadows. It can get noisy pretty fast in the grade and one must be careful. This only applies to the 1080p footage. Once we see 4K images I’ll know for certain.

So, what to do? There are two ways to grade S-Log2 footage:

  • Use LUTs
  • Grade from scratch

 
Here’s my honest opinion: Use the latter system in grading. Applying LUTs/presets/effects without knowing what they’re doing is why most people get crappy banding and noise. Some important notes from early experimentation:

  • There is an official S-Log2 to Rec. 709 LUT by Sony, but it applies to the gamut of the Sony F55 camera, and doesn’t look all that good with A7s footage. I would NEVER use it.
  • If you want to use a LUT right now, then the closest and most pleasing starting place is the Alexa CLog to Rec 709 LUT. It is slightly contrasty, but that can be easily corrected. I would only use this LUT while monitoring, and NEVER for the grade. It is a handy reference to keep within Rec. 709 colors.
  • All other camera RAW/Log to Rec. 709 gammas are crap for A7s footage IM-not-so-HO.
  • Just as a starting place, I’ve put together a LUT based on the Alexa LUT in Speedgrade. NOTE: Do not use it for critical grading or monitoring. It is just an experiment highlighting what can be achieved. The goals of this look/LUT are to preserve shadow details, preserve white balance, reduce the effects of moire, maintain highlight information, stay in full swing at 32-bit, keep dynamic range and remain within the pleasing range of the Alexa LUT. It is a starting place for further grading. Here’s the download (ZIP, *.look and *.cube) for you to try. Please tell me what you think.

 
You can use the LUT in Premiere Pro (via Lumetri), After Effects, Speedgrade and Resolve. The transition from full swing to studio swing in Premiere Pro is acceptable (at least to me!).

Overall, I’m extremely excited about the footage from the Sony A7s, even in XAVC S-Log2 mode. It is very filmic (the Rec. 709 mode is horribly video-y).

Multicamera editing

The Sony A7s has unexplored features for multi-cam editing:

A7s workflow

Until I have further information, I’m not going into details here. Just for starters:

  • TC refers to timecode.
  • UB refers to User Bits. It is eight digits in the hexadecimel system written as XX:XX:XX:XX. The cool thing is you can assign values yourself to this. E.g., in a mult-cam setup, if you have four cameras (C1 to C4), you’re in reel three (R3), scene 12 (12) and shot 4 (04), you can write out the UB code as follows: C3:R3:12:04. This helps synchronize cameras in a multicamera editing environment. Whether or not this is useful remains to be seen.
  • Rec flag is a record start/stop flag

 
Initially, I felt the Sony A7s is capable of genlock via an external recorder. Let’s see if this is true or not. I’m pretty sure the camera will throw up more secrets as time goes by!

This brings us to the end of the Sony Alpha A7s guide. I hope you have found it useful. Please let me know your thoughts and experiences.

 

35 replies on “The Sony A7s 4K Guide (Part Eight): Post Production and Grading”

  1. Hello! Does somebody know how to introduce the XAVC S Format Footage with 100fps into the AVID Editing Program? Do I need a special plugin ? And do I need to transcode the 100fps into 25 fps via another tool ? Thanks a advance!

    1. Unfortunately, xavc-s is still not supported in avid. The plugin only works for Xavc-l or Xavc-i. You can transcode with the free Sony catalyst software or record to avchd an import in avid.

  2. dear all. we are fresh a7r2 owners and wonder how to deal with the xvac-s files. with the canon c100 came a handy tool that would combine and rename the avchd files in a simple folder you can choose. the file names are generated from exif data. 
    now we’re looking for something similar for the xvac-s files. when we import with play memories home (is that a good idea?) the program makonly way to rees folders with date of the shots and the xml-files get lost (do you keep them?). the only way we found out to rename them is a program called a better finder rename (mac). we can make the files look like this: 20150805-054403 C0009.mp4 (the time and date is created from the file creation date). 
    do you think this is a plausible way to archive the footage (we hate 1001 C0001.mp4 clips)? or would you know a better workflow? 
    greetings from sunny switzerland

  3. Sareesh Sudhakaran JohannesDerkannes Why only s-gamut? I’ve heard that the s-gamut is indeed fake and only emulating true s-gamut on the a7s. That is why you get the ugly results from the f55 LUT

  4. Did you ever find out if it was possible to genlock two a7s cameras? I am interested in 3D recording with two a7s and two Shoguns.

  5. Hi,

    Thank you for putting together this guide. Very helpful but I would like to go further. 

    1. You didn’t talk about slow motion. I’m using Adobe Premiere Pro CC now and I still use Cinema Tools from Final Cut Studio but this time it doesn’t read the MP4 file (XAVC-S wrapper) so I’m doing it through Premiere now.
    I don’t think I can get the best result doing it that way. Is there an alternative?
    By the way, why is there an XML file attached to the clips in the XAVC-S wrapper?

    2. The workflow for grading is still confused to me. Should I convert my footage in a different format after my edit and send it to Da Vinci Resolve or could I just export an EDL or a XML instead?
    I just don’t want to do something wrong that would prevent me to use the full capacity of XAVC-S footage when grading.

    Thank you!

  6. ,

    i am a german dude, so sorry about my english. 

    my question is: you prefer the s-log mode, but what colormode do your prefer? Rec? S-Gamut? Pro? Cine? 

    i hope for a answer. 

    best wishes
    johannes

  7. Sareesh Sudhakaran tommyjojo thank you Sareesh, I won’t hold my breath for tech support, but thank you for the guidance

  8. Sareesh Sudhakaran tommyjojo
    thank you for the help…Adobe doesn’t read the xavc files, only mp4 on my machine…maybe adobe has a plugin?

    …when I imported into fcpx, they all showed up.  go figure

  9. I am a bit confused on the workflow w xavcs.  I recorded xavc-s but when imported into premiere pro (CS8.01.2)
    it sees the files as AVCHD.  What am I doing wrong?

  10. Thanks for getting back. The “magic” import of Sony files via PP and SG in the 2014 versions of CC works but makes me a little nervous. That said the Slog 2 grade is pretty tricky in SG. Since we do mostly real estate videos with this it would be wonderful to have the  dynamic range as we do inside shots with outside views that challenge even raw. 
    What I’m finding currently is that PP5 is a better starting point for now. Easier for me as a novice grader. I see the potential and will try to develop LUT’s of my own to so that I can just use them in Premiere but I need a bunch more testing before I feel confident in getting what I need  PP7.

    The A7s continues to amaze but I do need to find the sweet spot to avoid noise in the shadows. I look forward to any discoveries anybody makes here.

    Thanks again.

  11. The noisy shadows can be avoided if you overexpose by 1.3-2.0 using the built-in meter. Works quite well. Seems the sensor is very light hungry!

  12. I don’t see the A7s files (except as names )in speedgrade cc.  Since you didn’t make mention of this I was wondering how you got the files to display as clips. I see them fine in Bridge, in AE, and in Premiere but not in speedgrade. Any thoughts?

    Thanks

  13. shootsharp  The Shogun has no limit. Let’s hope the camera doesn’t as well. But really, 30 minutes of Prores HQ 4K is about 200 GB. Even with a 256 GB drive, one wouldn’t worry about the time limit!

  14. it’s unfortunate. but I’m sure with a proper recorder, say a atomos ninja star or a shogun, you could roll endlessly

  15. Great series, as usual. I so much appreciate your more detailed and technical approach to product reviews.

    Question re the A7s recording time: First, this is such a welcome package of on-board 1080 and out-board 4K capability!

    And I was especially excited to hear early on that there was no 30 min. recording limit. A time limitation has marred many dslr recordings.

    BUT now–late July– we seem to hear that there is, sadly but in fact, a 30-minute limit. Looking through many spec sheets, no recording duration limit is shown.

    True that it is limited to 30 minutes??? And, if so, is that only for internal recording??? Or, does this limit also apply to external recording???
    FWIW, I would gladly consider paying an upgrade or cost premium to overcome the tax or tariff increment that Sony avoids by classifying this camera as a stills camera, if that is the issue.

    I look forward to your ongoing articles.
    Yours,
    Mike

  16. shootsharp There are three things you can do: Expose, View and Grade. Out of these three, LUTs are only intended for the second.
    There are many who use LUTs as a quick-fix like a cinema effect just because they’re too lazy. Some use them as a starting place for a grade. However, that’s not what they are designed for. They are just an guide. Everytime you apply a LUT, you are reducing the quality of the image.
    E.g., the reason why I recommend never to use the F55 to Rec. 709 LUT is because it’s a 1D LUT, not a 3D LUT (like the Alexa LUT).
    In the case of the Pocket camera, BMD provides a Film to Rec 709 LUT so you can see what it might look like. It’s not intended for anything else.
    The correct process is to first build LUTs based on what you want, then use that on set to view your image (but only if you want to), and maybe send it to the editor (only if he wants it), and then use it as a memory aid/reference during the grading, where it’s not uncommon for the DP to come back after doing many other projects, and having forgotten what he did.
    But the grade starts from scratch. No LUT. This is the way I advocate. Feel free to read the links provided. It’s not as hard as people make it out to be, promise.

  17. i see… i can respect that. certainly i’ve seen lots of great color work done through the years, and its hard to imagine all of it is so subjective to an individuals personal perspective. there are so many LUT’s out there, and i’ve debated whether something like signing up for Color Grading Central is worth it. i’m a little confused about how some of that stuff works. for example: say i’m using my pocket cinema camera, and i am shooting in film gamma. when i come into my davinci resolve to develop it and i have a color cast (lets say it skews green for argument sake), are LUT’s intended to be applied directly to the footage before i correct my color cast or after? or does this depend on the LUT?
    for my intents and purposes, i love how the color checker makes my footage look WAY more than anything i’ve been able to do on my own up to this point. but i would love to grow and improve

  18. shootsharp The simple answer is that not every DP wants accurate colors. Many manipulate white balance, filters, looks, etc. I don’t use it either. E.g., I like red the way I see red, not the way it is printed on the passport. Secondly, not all cameras can reproduce colors accurately at the same time. Fix one, and another goes to pot, and so on.
    However, for reproducing product shots or logos or designer wear, etc., where color reproduction is critical, it is an important tool.
    Every NLE has an eye dropper tool, and usually you just need to white balance correctly for video work.

  19. oh ok, i didn’t know it could be done before davinci resolve 11 so it was possible before that? anyhow i’ve been testing it more and getting amazing results. i don’t see why a color checker doesn’t come bundled with a blackmagic pocket cinema camera, because before this i was getting AWFUL results. i’m really trying hard to learn, but its tough without knowing how to get to a good starting point and this really makes that easier

  20. shootsharp  Thanks for sharing! Using the passport is a time-tested method of exposing and matching cameras. It is extremely invaluable for critical color reproduction.

    I’ll try to put together something soon.

  21. hi!
    thanks for the guide to the a7s. I’m an owner of the blackmagic pocket and as of yesterday also a a7s, and appreciate the guides you’ve made.
    as far as grading, or “color correcting” at least, I am a complete amateur, just beginning to learn. but what I’ve been doing has totally changed my workflow and I wanted to share. have you read about the feature in DaVinci Resolve 11 Beta that used a X-Rite Color Checker Passport? at the beginning or end of every clip I slate with the color checker and then in resolve I use their color match feature and BAM! pushing one button gets me to a solid starting point. it has presets for slog2 in their color match feature as well as BMD film gamma, and I did an experiment at my friends studio the other day in a test multicam shoot involving GH4, fs700, and a bmpcc. all were slated with the color checker and when I used the color match it REALLY did a good job. perfect? no. I could still discern minor differences. one camera might need more contrast and another might need saturation, but it got me REALLY close into the ballpark of where it needed to be.
    last night i tested the color checker with my a7s in good light and low light situations and once again it worked flawlessly (relative term). I highly recommend you explore this feature or give a review of it. would be awesome to see what you think of it.

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