Uncompressed 240 fps possible with FS700 and Convergent Design Gemini. Tested!

Using Convergent Design Gemini to capture the 50p buffer stream from a Sony FS700

Great news. I was able to confirm yesterday that it is possible to record the super slow mo buffer stream from the Sony FS700 to an external recorder. When you shoot Super Slow Mo with the FS700 the camera buffers the slow motion footage into an internal frame buffer before reading this frame buffer out and encoding it to AVCHD to write to the internal compact flash card. The footage is read from the frame buffer at 50/60p depending on which country area the camera is set to.

Setting up the output.

The cameras output can be set in the menu to either 25/30p or 50/60p, if set to 50/60p the HDSDi output is 3G. In either case the buffering happens at 50/60p. So FOR THIS TO WORK CORRECTLY THE RECORDER MUST BE 3G CAPABLE AND BE ABLE TO RECORD 50/60P, if the camera output is set to 25/30p you only get one field from each frame in the buffer stream on the output Sdi at 1.5G. So you end up with a slow motion interlace video stream with recorders that can only record up to 25/30fps. The end result of this is that if you shoot at 200 fps with the camera output at 25p you would end up with an external recording the equivalent of 100 fps with a 180 degree shutter. Every external HD recorder that I know of can record this as it is nothing more than 1080p25 (or 1080p30). A very useful and a nice option. To get the full benefit of external high speed recording you need to set the FS700 to output 50/60p over 3G SDi and then you must use an external recorder that has 3G SDi and can record at 1080 50/60p, something like the Convergent Design Gemini. Using a 50/60p external recorder you can then record every frame from the frame buffer. If you then take this 50/60p recording and slow it down by 50% in the edit suite you end up with full HD resolution, uncompressed 200/240 frames per second video. Very impressive indeed!

49 thoughts on “Uncompressed 240 fps possible with FS700 and Convergent Design Gemini. Tested!”

  1. Please explain a bit more clearly if you can record 1080 60p 4 2 2 to an external recording device at a fast bit rate.

    1. 1080 60p 4:2:2 is easy and can be done with either the Sony FS700 or PMW-F3 as both cameras can output continuous 1080 60p over the 3G HDSDI output. On the FS700 it is 8 bit and on the F3 it is 10 bit. For either you will need an external record that has 3G HDSDI and the ability to record 60p. The Convergent Design Gemini can do this (uncompressed) as can the Sony SR-R1 (SR Master 880Mb/s), maybe others too.

      It’s hard to explain the way the FS700 takes 240fps. The camera shoots 240fps for 8 seconds, recording this uncompressed in an internal memory buffer. After 8 seconds this stored 240fps sequence is the read out of the memory buffer at 60fps so that the camera can encode it and save it to the internal SD card. While this is going on the 240fps clip is also output from the 3G HDSDI at 60fps and it this that you can record externally.

      1. Alister Chapman,
        Thanks for the clarification. But, are you stating that the 700 will only capture 8 seconds of SloMo video? I would assume that Sony will come out with a better way of capturing SloMo in a future upgrade.

        1. The FS700 will only capture 8 seconds at 240fps. Most high speed cameras have similar limitations as the amount of data involved is just too much to write continuously to the recording media (uncompressed 240fps is about 8Gb/s compared to 30fps which is about 1Gb/s). Do remember that 8 seconds at 240fps results in a clip 80 seconds when long when played back at 24p. At 60fps you can record continuously.

  2. Dear Alister,

    It’s been a week now that I am researching on the best camera to buy and you have been posting the most resourceful informations out there. Thanks so much.
    I have a question here for witch I can’t find a precise answer:
    Can the FS700 output a 4:2:2 10 bits signal to an external drive (Gemini for exemple)? Or are we stuck with 8 bits what so ever?

    1. The FS700, like the FS100 only has 8 bit processing and output, so there is no way to get 10 bit out. Don’t be put off too much by 8 bit. With a good recorder even 8 bit can do very well. It’s only when you start to really push it in grading that 8 bit starts to show up issues.

  3. Thanks for the research, but I am going to have to keep looking. That Gemini is $6k from Beards and Hats. Spendy! Sound Devices has a nice one

    1. The only recorders suitable for doing this are those with 3G and 50/60P recording and there are very few of those.

  4. hello Alister,
    Thank you for this great article.
    One question though:
    why have you greyed out part of the article that has to do with recording slow mo with external recorders OTHER than Gemini’s?
    I have been trying hard to do it with a Samurai with no success (even though some poeple seem to have done it successfully with Atomos Samurai!), and it seems that it was possible to do it with earlier firmware versions. Now as soon as we get in slow mo modes the screen gets all green.
    Could you confirm this? I have been trying every possible
    Could it be that Atomos for different reasons is restraining this possibility?

    1. Only recorders that support 60fps recording work properly. When in Super slow mo 25/30fps modes the output from the SDI on the FS700 is interlaced and not progressive.

  5. This is really a half way concept.The form factor is all wrong.I much prefer a ENG style
    with a high resolution CRT,EVF,side mounted.Then the recording codec.28 Mb/sec.Really P2 had 100 6 years ago.Why should I pay for a external recorder to record to a better quality codec like the Gemini or Samurai.Having attending a local Sony presentation of this camera the Sony couldn’t tell me when the Firmware update
    will be available to shoot 4K.They all told me there are no 3rd party external recorders that will take the single 3G output and that they didn’t know if anyone was was working on it.In other words Sony will not put 2 HD SDI outs to talk to a 4K recorder,and the 3rd parties will not adopt a single 3Ger.When I asked about the F5 they didn’t anything about it.The Sony presentation was held on the 28th of August 2012 at Leonda’s by the Yarra Hawthorn Victoria Australia.

    1. Perhaps you would prefer shoulder mount, I do not and others will have different opinions depending on the type of shooting they do. No one form factor will ever please everyone. 28Mb/s AVCHD is actually much closer to 100 Mb/s AVC-Intra than the numbers alone suggest, don’t forget AVCHD being interframe is far more efficient than AVC-I. In my opinion AVC-I 100 is a bloated dinosaur of a codec. To use a 100 Mb/s codec would require significantly more expensive recording media, need more power and greatly increase the overall cost of ownership. If however you do need to record to a higher bit rate there are plenty of external recording options.

      The information you have is incorrect. There are already several external 3G recorders on the market, the Gemini, Cinedecks, KiPro Quad etc. It is now easier and cheaper to implement 3G than dual link 1.5G. The Gemini and KiPro Quad can both use 3G to record 4K and most future 4K devices will almost certainly use 3G as the 3G standards include provision for 4K and there are no sync or latency issues as can occur with dual link. Dual link 1.5G is an old legacy standard that can be adapted to work with 4K, but 3G is far better for 4K. But, as yet Sony have not decided on exactly how they will output 4K raw from the FS700 and what they will allow as a recorder. It is not as simple as switching on the 4K output as the signal will be raw sensor data, not a video stream in the traditional sense, so any recorder will have to understand the signal correctly and there will also need to be a set of suitable de-bayer and post processing tools. Sony have to be fair always said that this is not going to happen overnight.

  6. Hi Alister,

    really useful post – many thanks. Can I just make sure I’ve got my head around this:

    From what you are saying when the FS700 records at 200/240fps it records true progressive. When set to output 25/30fps it outputs true interlaced – ie it takes one field from each 50/60fps frame. When it outputs at 50/60fps it outputs true progressive.

    Is that right?

    1. Yes, that’s what I am seeing during my tests. The camera output must be set to 3G to get the 50/60fps output.

  7. Thanks for sharing all of the work you’ve done here. I’m currently checking out the FS700/Gemini combination and have a triggering question: When you were doing your test were you able to trigger the Gemini via the embedded time code in the SDI? Although we find that the Gemini is recognizing the embedded time code it doesn’t seem to be shaking hands when it comes to auto triggering during the buffer dump. Oddly enough, a nanoFlash attached to the same feed but outputting at 50i will trigger recording on and off in perfect lock-step with the internal recorder. Everything on the Gemini seems to have the right settings – it’s a nicely intuitive user interface. We’ve contacted Dan Keaton but wondered about your experience with this.

    Stephen McCarthy

  8. Ah! now I see. The camera (in addition to the “output”) needs to be set to 50P. That would make sense in terms of recording t.c. matching that of the output. I expect this downgrades the resolution of the internal recorder but doesn’t seem to effect quality of the sdi 3G. Was that your experience?

    1. When you set the camera to 50P the bit rate rises to 28Mb/s from the normal 24Mb/s. This may not appear to be much of an increase but the higher the frame rate the smaller the differences in the images from frame to frame, so you don’t need quite so much data to record it.

  9. Just received my camera. Im a bit confused about how the FS700 outputs to an external recorder in slow motion? From what Im getting you must make the output 50/60 in order for a 3g sdi recorder to receive a progressive signal. How do we get the full 240fps if the recorder is only seeing 60?

    1. The stream during the buffering process 240 fps video played at 60p. You record the 60p stream and then play it back at 24p to get the full 10x slow motion.

  10. One more question. The FS700 4k raw 12bit will be available soon. The ki pro quad and the gemini raw should be able to handle that. Looking at the specs they only record 10bit raw 4k. Will there be or is there a recorder that can record the full 12bit? The Blackmagic records 12bit straight to ssd. Also do you know if the slow motion features will still be functional at 4k or is stuck at 1080p?


    1. No one outside of Sone management knows when the update will be available and how it will work. It may be compressed or may not be compressed, we don’t even know what the resolution will be, 4K or Quad HD?

      What is almost certain is that Sony will produce a recorder that can record the full output, whether 3rd party recorders will be able to record the output is still unknown.

  11. Hi Alister

    Thank you for all your great info.

    Guys over at DVX are claiming the 3G SDI out is not pumping out 50/60P on the production model FS700.
    Is this true? have Sony disabled it since your testing of 240fps out buffer 60P to the gemini? Did you do your tests on a pre-production model?
    Please take us out the dark, as I assume you have a production model.

    Many thanks


    1. There is no difference between the pre production and production firmware and the production units do output 50/60P over 3G HDSDI. The issue is very few people actually have 3G capable devices that can record 50/60P.

  12. Hi Alister,
    Saw your post on the BM Hyperdeck shuttle not recording 3G.
    I’m going to test the FS700 for a drinks pour shoot and want to capture the 3G out at 60p.

    Will my BM Decklink extreme 3D capture card do the business? (it says it can record up to 10 bit 3G??) . Also is there any merit in setting the shutter speed higher than the frame rate eg 250th at 240 FPS as I have noticed some smearing when leaving the camera to determine shutter speed.

    Thanks for all your help

    All the best.


    Fellow Productions

    1. The Decklink extreme should work. There will be little benefit in using a faster shutter in super slow mo.

  13. Hi Alister. Have you had any success syncing up timecode on the the 700 with other cameras? I can sync my P2 recorder (HPG20) to its embedded sdi timecode. I can also jam sync my P2 recorder to my full size P2 or HDcam, then unplug and leave it in free run. So it sort of works as long as it doesnt drift. this way I’m only syncing when recording externally. What I really want is to sync the camera. It says it outputs tc thru HDMI – is there any way of reading that to a timecode in on a professional camera? My searches have failed.
    Thanks, Mark

    1. Not unless you have an external recorder that has a separate Timecode Out to allow you to then plug the 700 into the recorder and strip the timecode off the video feed to send to another camera. The FS700 isn’t really designed for this type of application.

      To be honest TC is less important these days as it is very easy to sync multiple cameras in post production using the audio tracks.

  14. Dear Alister,

    how do you put the settings to record 240 fps from the camera automatically with the Gemini? Or do I have to start the Gemini manually with the record button after pressing the trigger button on the camera?
    Best wishes

  15. Hi Alister you said that to record true progressive with FS700 and an external recorder the output must be 50/60.
    But what about if you record internally on sd/flash memory with 25p output? I know that footage will be compressed in AVCHD but will you have interlaced footage anyway? That will be odd considering the “p” on the output…


    1. It’s only the external output that is not progressive in super slow mo (unless you use 3G 50/60P). The internal recordings are progressive.

  16. I stumbled upon this article and the quite interesting stream of questions and answers and thought I would add a note on the FS700 firmware upgrade. I talked to a Sony rep at the CCW show in NYC the other day about the upgrade. He told me that they are still working out post workflow issues for the RAW 4K output, and that is apparently the holdup. It will be April or May, apparently, before they have it ready to roll. But on the brighter side, it will be UNcompressed, 12-bit which will be recordable on either the new Sony recorder or three (unnamed, but not hard to guess) 3rd party 4K recorders.

  17. Hi Alister,

    thanks for this information, thats great!
    We didn´t test the recording with an external device yet, but we´ve experienced another issue.
    When connecting an external monitor (over SDI or HDMI) we see a 3-4 frame delay, which means during dialogue actors are not in sync and puling focus is a pain.
    Are you seeing this too? I think we ran the unit in 25p mode. will it work better using 50p? Do u see that lag too?


  18. Hi Alister,

    I was wondering if you know about using the Gemini with the F5? Any reason why it wouldn’t work?

    Thanks, Richard

    1. As it stands it would only be able to record the HD outputs, so it could be used for S-Log2 or standard/hypergamma HD recordings.

  19. Hi Alister,
    Thanks for your blog it is extremely helpful.
    I just purchased the Gemini 4:4:4 for my Sony fs700. In your experience, what is the highest frame rate I will be able to record at 10 bit 4:4:4 out of the Sonys 3gSDI. The Gemini manual say’s only 30p at 10bit 4:4:4. 60p at 10 bit 4:2:2. I would like 120fps or 60 at 10bit 4:4:4…is that possible?

  20. I have shot 200fps on the fs700 and output 1080/50i buffer stream on the hdsdi to a samurai ext recorder (samurai wont take progressive but interlaced works fine) and got perfectly fine super slomo results in prores 422 at around 140mbs. However I am told that this will not pass broadcast standards because of the way the fs700 “packs” the slomo. Any idea what this means ?

    1. The problem using a non-3G recorder and taking the 25P/25i buffer stream is that the camera is running at 25fps. The buffer stream is recorded and processed in the FS700 at either 50fps or 60fps. So you are only getting half resolution as the only way the camera can show a 50fps stream on a 25fps output is by dividing each of the 50fps frames in half and using the even lines from the first frame as field one and then the odd numbered lines from frame 2 and using them as field 2 in a 25i stream. So for each 25fps/25i frame the upper field comes from one frame and the lower field from the next. The end result is that each frame of your slow mo contains 2 of the original 200fps frames split into fields and then combined, so it’s no longer 200fps progressive slowed down to 25p, it’s now 100fps interlace slowed down to 25i. In addition as this is not antialiased correctly (no line averaging as occurs in a true interlace scenario) it can suffer from a lot of aliasing and other undesirable artefacts and this makes it unsuitable for broadcast.

      If you have a 3G capable recorder (Convergent Design Gemini or Cinedeck) you can set the FS700 to 50P and the output to 3G. Set like this, the buffering once again occurs at 50fps, but as the camera can now output 50fps each frame can be fully output to the recorder at 50fps full resolution during the buffering process.

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