By technical editor Matt Allard:
The Atomos Samurai set to record the HDSDI output of the FS700
After my last blog post a few readers wanted to know if the image quailty of the NEX FS700 could be improved by recording to an external HD SDI recorder. Well in short the answer at the moment seems to be no. Sony have said the camera will be capable of outputting a 4K 12bit RAW image at some point in the future but sadly it only outputs 8 bit 4:2:2 over the HD SDI output at the moment. My interest here is solely in actual image quality so I’m not going to go into all the technical reasons for this – if you are interested in finding out more there is plenty of in depth technical information around the web.
FS700 AVCHD 24Mb/s vs ProRes 422 220Mb/s from Matthew Allard on Vimeo.
For this test I recorded to the internal SD card at 24Mb/s in AVCHD as well as to ProRes 422 HQ at 220Mb/s on a Atomos Samurai recorder. My conclusion after looking at direct comparisons of the two is there is little if no difference in image quality. Even when blowing up the image there is virtually no difference. There was no improvement to the quality at higher ISO either. The only point to record to an external recorder is to have a back up copy of your video files and for faster turn around time of material because it is already in the Prores (or other) format and does not need conversion. Just like Canon’s C300 there seems to be almost no reason to use an external recorder with the FS700. The 8 bit HD SDI output offers to my eye almost zero improvement over recording internally.
What may also be very exciting for news shooters further down the track for is tha when the 4k finally becomes enabled you should in theory be able to use a 2/3″ ENG broadcast lens and still get a full HD 1080P image by cropping the 4k image. That said I have my doubts though as to how good the quality would be from a 2/3″ lens – time will tell.
About Matthew Allard, Aljazeera Senior Field Cameraman, Kuala Lumpur:
Matt has been a Camera/Editor in TV news for more 20 years, previously working for both Channel 9 and Channel 10 in Australia. Twice Network Ten Australia’s cameraman of the year as well as being a Walkley Finalist for outstanding camerawork in 2006 (for coverage of the Cronulla Race Riots) and a Logie Finalist for outstanding news coverage 2006 (Bali 9). He is a multiple ACS (Australian Cinematographers Society) award winner. His Sword Maker story that was shot on a 7D won the prestigious Neil Davis International News Golden Tripod at the 2011 ACS Awards. He has covered news events in more than 35 countries, from major sporting events to terrorist bombings. Based out of the Kuala Lumpur broadcast centre in Malaysia he is an avid user and follower of new technology, shooting stories on HD broadcast cameras, the Sony F3 as well as new Canon DSLRs.
3 responses to "Does the Sony NEX FS700 image improve when using an external recorder?"
jblondes Says:
November 25th, 2012 at 6:46 am
Matt,
This is very interesting, and for a neophyte like myself, extremely illuminating. Thank you.
I asked the following on someone else’s blog, but have not had a response. From you film, it would appear you answer one of my main questions:
“I’ve recently purchased the Fs700 and a Samurai. I’m confused about the resolution differences when recording to the internal SD card versus any of the three resolutions on the Samurai… ProRes HQ, ProRes422, ProRes LT.
The file sizes of the resulting sequences are significantly different. Does it follow that the higher the Mbits/s, the higher the resolution and therefore the better the image, or is there a point at which a larger file is simply larger without any significant improvement in image quality.
For the most part, my films are viewed on nothing bigger than 60″ screens. Is it beneficial for me to be filling up hard drives with content filmed in ProRes HQ on the Samurai, or do the sensors of the FS700 only give some maximum resolution in any case.
Is the quality of the image recorded to the SD card the maximum quality possible with the camera, or does the Samurai record a better image… is there a way to change the quality of the file recorded to the SD card to match the Mbits/s of ProRes HQ on the Samurai?”
Thanks in advance for helping to fill me in!
Matthew Allard Says:
November 25th, 2012 at 8:03 am
Hi jblondes,
The FS700 records 8 bit 4.2.0 internally. Through HD SDI it is still only outputting 8 bit. Recording externally at a higher bit rate such as ProRes offers will help with scenes that feature a lot of movement or that require complex colour grading in post. As the output through HD SDI is still limited to 8bit your image quality will not improve drastically, in fact you may have to look extremely hard to see any difference. If the FS700 could output 10bit 4.2.2 for instance a lot would be gained in going to an external recorder. The only reason I use an external recorder is so I can avoid using AVCHD and go straight to ProRes. I hope this makes sense.
jblondes Says:
December 8th, 2012 at 9:40 am
Matt,
Thanks for your response. I’ve just run a series of tests comparing the various recording qualities on a Samsung 55″ screen and agree with you that it is extremely difficult, looking at raw, un-edited footage, to see much difference between the various settings.
That said, ProRes HQ always seemed to have just a touch more detail in the most subtle of subjects… veins on a leaf for example, than either AVCHD on the SD card or the other ProRes 422 on the Samurai.
It was ever so slight, such that unless you were switching back and forth between two files and minutely comparing, that I’d be amazed if anyone would be able to see a difference on the wall.