I wouldn't say those are the only reasons for external recording. 1080p downscaled from 4k externally can be quite a bit sharper than what the a7S records internally.

It depends how you are downscaling. The a7S's 1080p is good and fairly sharp, but certainly a good step drown from the sharpest oversampled 1080p. A different scaling algorithm will produce sharper 1080p than you're seeing.

lanczos is regarded as one of the sharper scaling algorithms. You could use ffmpeg with a command like this:

ffmpeg -i input_filename -vcodec libx264 -x264opts qp=14:ipratio=1:pbratio=1:keyint=30:colormatrix=bt709:colorprim=bt709 -s 1920x1080 -sws_flags lanczos -pix_fmt yuv420p -acodec aac -strict -2 -b:a 320k output.mp4

The video encoding options are for very high quality H.264.

There is a video that seems to show a hacked a7s with internal 4k. It could be a fake...what do you think?

@Pedro_ES

No need to post it here. Anything like this requires big work and knowledge.

@kingmixer That looks really great! Nicely done - definitely makes me wanting to see the rest!

http://www.mirrorlessons.com/2015/10/02/going-nomad-to-film-the-world-with-the-sony-a7s-an-interview-with-filmmaker-brandon-li/

@Vitaliy The Nabil Fathi's procedure has any chance to success?

Is this a fake? I'm quite skeptical about this hack, but I also don't know how it is supposed to be used. Anyone with some knowledge can shed a light on the subject?

UPDATE: I just opened the package, and found:

App Source Code include Sony Imaging Source Code Sony Base Source Code Sony FW Source Code Sony TimeLapse Example Source Code Sony AVI Source Code (Use by TimeLapse App Example) Sony Util Source Code. This is not 100% Source Code of the Sony Camera System This is at least 80%. I will release other alternative Source Code. Why this is helpful ? Anyone who have a experience in Java/Android Coding can build a application based on the actual source code This give you the possibility to call specific function of the camera. You can control the entire camera and even build third party control. AVI source code is a good example of what is possible to do. The last few weeks I discover how to reverse engine the system. How to gain access by injecting code and bypass root permission problem. I’ve been able to dump important information about the system. To let you know, that source code has nothing to do with the PlayMemories camera remote API SDK. The Camera remote SDK provide only a way to control your camera remotely not to gain low-level control or build strong app etc… Sony will never share the source code of their system layer, because they are needed to make important app for your Camera and this will be problematic, anyone could control the camera in a high advanced way. I’m going to repeat, the source code I share is bigger than you think, far more bigger than what was release recently, because it include all the boot process, layer control, dsp/soc control, etc… that give the capability to the play memories app to gain low-level access and third party control. Again you can build third party app based on the actual source code and make something really big of it. Right now I’m finding how to flash the firmware by using a SD Card in a certain service mode (something I share on Olympus camera in the past). But with this big open source code, it is completely useless, you can even install apk directly from the SD Card without the need of PMCA anymore, you only need to build an Android app for that and place your apk on SD card. Few problem with the Sony System. Sony can block that by removing in the future play memories access or restrict completely. Sony can release a firmware and block everything You mostly need to respect what have on the source code and limit your application to specific priority, also work under GB SDK. When you reset the camera, you lost the application. At the moment, you will need to install the APK using the PMCA website. https://sony-pmca.appspot.com (mostly work with IE explorer, main problem with other browser is that they disable the NPAPI function) but you can try. Here’s the source code of PMCA by ma1co https://github.com/ma1co/Sony-PMCA-RE Basically you have class/string for certain function of the camera XAVCS4K for example -> public static final int XAVC_S_4K = 2130772533; This is just a example, I’m not going to explain the entire source code. Camera compatible ? Basically almost all the play memories camera, including a6000. RX100M3, etc… Do want you want to do with the source code, have more to come, I have confirmation that one sure coder build a android app based on this that will offer extra features. Enjoy and be creative. I’m done with Sony Camera. Nab

So we just need to wait for some Android programmer to use the source cose and build an app...

@flablo

Please, use proper formatting with citation (put > before paragraphs).

Proper topic is http://www.personal-view.com/talks/discussion/12756/sony-alpha-hacks-talk#Item_15

It is very hard to understand that this guy mean and as I understand it is just files distributed by Sony in the open.

N-Log vs S-Log2. quick grade in CC works very well

Sorry man, but the Nlog is graded? Because if it's not, there is less dinamic range then Slog, I think.