FS100 and F3, Alister's Video

[Alister Chapman]

HDMI 1.3 and above supports 10-bit, 12-bit and 16-bit (RGB or YCbCr), although true 10 bit let alone 12 and 16 bit monitors are not at all common. There is a small range of 10 bit monitors (Hazro) and quite a few TV's that have 10 bit processing and 10 bit panels, but to get the most out of a 10 bit pipe you want processing that is at a higher bit depth than 10 bits.
The Atamos Ninja has a 10 bit pipe as well as most of the Current BlackMagic and Matrox HDMI capture cards. A 10 bit HDMI recorder will be able to record the DeepColor output, on an 8 bit recorder I assume it is simply truncated.

From what I've been able to find out, the BlackMagic capture cards (including the shuttle) are all 10 bit YUV (YCbCr) which suggests that cameras output YCbCr, but that is speculation based on manufacturer data sheets. You can have either 4:2:2 or 4:4:4 YCbCr over HDMI 1.3.

I would hope that the HDMI output is YCbCr to avoid having to cross convert from YCbCr to RGB and back again with the potential for color space reduction if it's not done exactly right.

[Buba Kastorski]

Mr. Chapman, thank you for the test,
once again, what a nice piece of camera is F3, but FS100 footage to me looks just like VG10

[Alister Chapman]

The FS100 is a lot better than the VG10. There is minimal aliasing for starters. The brickwork of the houses would have not looked good on the VG10.

[Mark David Williams]

Actually I would consider buying the VG10 over the FS100 especially if your using the camera for DOF control and in combination with say an EX1 for wide shots. I wouldn't be concerned about aliasing if the backgrounds out of focus anyway.

Mark

[Alister Chapman]

But aliasing and moire can occur on skin texture, facial hair, eyebrows, eyelashes, hair and clothing plus it messes up compressed codecs and broadcasting systems big time as if there is any movement in the image the aliases travel in the reverse direction, doubling the bandwidth required. It's ugly and the best way to make video look like video, especially on a big screen where flickering lines and false colour moire are so much more apparent.

I had hoped that cameras like the FS100 would allow us to leave the era pixel skipping and highly aliased images behind.

[Asif Khan]

Originally Posted by Buba Kastorski

Mr. Chapman, thank you for the test,
once again, what a nice piece of camera is F3, but FS100 footage to me looks just like VG10

FS100 and F3 has the same sensor, and I pretty sure with correct setting (in this case lower exposure), FS100 can be made to look just like F3 in these "tests."

[Mark David Williams]

Asif

It may have the same sensor but that's only part of the equation.It's only got 8bit processing and 8 bit out for example. There is also definately some jiggery pokery the F3 has going on that the Fs100 doesn't.

[Alister Chapman]

The FS100 processing is 12 bit, using components from the lower cost NXCAM range and the processing is tailored for a 4:2:2 8 bit output. I expect the DSP only works with 4:2:2 colour space, although I could be wrong.

The F3's processing is I believe also 12 bit, but it's output has to support 10 bit 4:4:4, so the likelihood is that the DSP's internal processing is 4:4:4. It also has more advanced detail correction and aperture correction circuits along with a wider range of gamma curves.

Small differences perhaps but they can make a noticeable difference in the final image quality. In Rec-709 the differences will be minimal and it will probably take a side by side comparison to highlight them. Switch to the Cinegammas or S-Log and the F3 will have definite dynamic range advantage.

[Mark David Williams]

Hi Alister

This is from the creative video site I read it somewhere else too that its signal procesing is 8bit and is the reason it could only have 8bit out.

Sony NEX-FS100
The FS100 shares its sensor with the F3, however the similarity ends there because its signal processing is 8-bit

Quite interesting to hear it uses components from the lower cost range.

Mark

[Steve Mullen]

Originally Posted by Mark David Williams

Actually I would consider buying the VG10 over the FS100 especially if your using the camera for DOF control and in combination with say an EX1 for wide shots. I wouldn't be concerned about aliasing if the backgrounds out of focus anyway.

Mark

In all my time with the VG10 the only aliasing I saw was on a brick building and it was very slight. It's far less than from the Canon cameras that some folks fully feel is "broadcast quality."

Were the VG10 available w/o a lens and thus at a much lower price AND were the newest firmware to add Focus Assist OR Peaking OR One-Touch Focus, it really could be a OK buy. Without better focusing aids you either must use E-mount AF operation or pray you got focus right.

VG10 lesson: Before pressing record, press the shutter-button and the camera will run through the entire focus range and lock the best focus. Now disable AF and shoot. You will have a better focus than you can get by eye on the LCD or VF when in bright light. (Yes, there should be one-touch focus button -- just one more thing Sony left out.)

But, I still say wait! A new version is "expected" by many in the next few months. If it adds the missing focus features it's worth the wait. If it is a 4K2K camera, for some of us it is definitely worth the wait. And no I do not expect 1080p24 or 1080p25/30 as Sony wants to keep this in the consumer camp.

[Mark David Williams]

Steve

Why can't you focus using an external monitor? The first thing that would go for me would be any on board auto focus. I know some cameras you can program focusing or follow a target or rack focus but all these things can and usually done anyway with a follow focus and for the price who cares. Peaking would be nice though.

[Alister Chapman]

The internal processing must be done at a higher bit depth than the output, otherwise there is no headroom for calculations. An 8 bit DSP will not give a good 8 bit output. It is also reasonable to consider that the output from the sensor will almost certainly have an output that is 12 bit or more to get the dynamic range that the F3 can provide and simply taking 12 bit's into an 8 bit DSP would seriously degrade the output.

[Mark David Williams]

Originally Posted by Alister Chapman

The internal processing must be done at a higher bit depth than the output, otherwise there is no headroom for calculations. An 8 bit DSP will not give a good 8 bit output. It is also reasonable to consider that the output from the sensor will almost certainly have an output that is 12 bit or more to get the dynamic range that the F3 can provide and simply taking 12 bit's into an 8 bit DSP would seriously degrade the output.

If that's true and from what I can find out the processing is 8bit because of the heat generated, then there are more problems on recording to an external recorder like an atomos?

I also wonder how digital noise reduction is applied and could this affect the resolution of the Fs100?

Mark

[David Stuart Shapton]

Interesting discussion and I just wanted to contribute with a couple of points that may shed some light on things.

First, as has been mentioned elsewhere, the internal processing on any digital device is always higher resolution than the output. Think of it like this. Most of Digital Signal Processing is multiplication and addition. If you add or multiply two numbers together, you get a bigger number. So if you add or multiply two numbers that are already maxing out the 8 bit resolution (let's say 255 x 255) then you're going to get an number that is bigger than you can represent with only 8 bits. The result is distortion.

In reality, there is some extremely complex processing going on all the time in these cameras, the detail of which we can only guess at. How it's done exactly is a closely guarded commercial secret and nobody should be surprised if the manufacturer doesn't want to reveal their innermost workings.

You can't really gauge the quality of a camera solely on the bit-resolution of it's output. It's quite conceivable - but pretty unlikely - that a bad 10-bit camera could look worse than an extremely good 8 bit one. You have additional factors like noise, internal processing quality and a host of other things that can completely affect the quality quite independently of the bit resolution

The Ninja will always record in 10-bit resolution. This is a worthwhile stance, even though it might not actually improve the quality of an incoming 8-bit signal. By adding an extra two bits (as zeros!) to the incoming bitstream, it means that all subsequent processing is done at that additional resolution. All colour grading and dissolves will result in smoother gradients. Even adding a small amount of noise at the 10-bit resolution will dither the original 8-bit contours without actually degrading the picture from an 8-bit point of view. (Some of the early audio A/D converters actually ADDED noise, for this very reason - it simply made it sound better!).

Dave Shapton
President
Atomos EMEA

[Mark David Williams]

Hi Dave

This was Phil Blooms site re the FS100 although Phil might have it wrong it seems a few people have also mentioned the processing is 8 bit.

Sony FS100…just my first impressions | Philip Bloom
It has the same Super 35mm sized sensor as the F3 but different processing. It has no SDI out, just HDMI and it is only 8 bit 422 even though HDMI can do 10 bit 422 because the processor is only 8 bit. Compromises have had to be made to slash the price down from the F3.

Big fan of atomos by the way!