Zone plates for FS700 and FS100

[Matt Davis]

Got a chance to play with an FS700 very close to final release specification. Currently running tests on all sorts of things, but I'm no Alister Chapman or Adam Wilt, so my apologies in advance.

However, keen to share this early finding.

Zone plate shot on FS700 and FS100 - same lens, same setup. Tried 720p mode as well as 1080p mode on FS700. I'm impressed. Yes, there's a little bit more aliasing, but that's the price you pay when the detail's way up on the FS100. The forum previews look horrific, so you'll have to pixel-peep the full frame downloads. I checked them against the PNG originals, and you're not missing much.

[Felix Steinhardt]

Uhm, I don´t know how to read such plates but does the 100 have more resolution than the 700???

[Matt Davis]

Check the 'flutes' lef and right of the circle.

You're getting separation between the black and white lines at the 800 LPPH level on the FS700, just where the FS100 is giving up, just as the FS700 at 720p. The aliasing is more on the FS700, but there's more detail.

[Felix Steinhardt]

Ah, yes I see it. But isn´t that vertical resolution? I thought what´s interesting is horizontal resolution meaning TV lines.

I believe the maximum 1080p can do is about 1000 TV lines. Your plate shows only up to 800.
Would this be better to test resolution?
ISO 12233 Test Chart

And thanks very much for the test! I have a FS700 on preorder and the thing I dread most is that it again won´t resolve real 1080p like my old FS100. It was a real bummer to switch from the GH2 to the FS100 back then, paying a lot more and losing resolution...

What detail settings did you use on the FS100 and FS700?

[Matt Davis]

My bad - should have described the method:

Get loaner, proceed directly to friendly dealer with Chroma Du Monde and Zone Plate charts, shoot them, get back home and pour over the results. Therefore, no choice in charts, just what my dealer has in the showroom. :-)

The take home for me was that... yes, the FS700 delivers more detail, as shown by Frank Glencairn, but at the risk of a little more exposure to aliasing - though not as much as it could have been (with reference to Philip Bloom's shot of Richmond Lock).

To be honest, there's a side bet going on here: that 720p50 on the FS700 is a better bet for SD than the native 1080p. The EX1 had a slight excess of detail at 1080p for decent SD, so the trick was to shoot and edit 720p, then export to SD in a 4:2:2 colour space. The FS100 didn't necessarily need this with 1080p50, but the extra amount of detail in the FS700 warranted a reality check for 720p and whether it shrank down nice to SD.

Anyway, I'm happy with the extra detail, and will live with the risk of alising - my FS100 will be the wide/gv camera, the FS700 the cu/detail camera.

[David Heath]

It's very interesting.

The point about zone plates is that they act like fingerprints and are MAINLY determined by the chip characteristics, less so by other matters. A bit like different fingerprints from the same person may look different because of smudges etc but they will all have common features good enough for a unique identification. Same here - detail settings, lenses, defocussing etc can affect the appearance of zone plates in some ways - but certain chip characteristics will remain unchanged.

As far as your examples go, then I've tried importing them in to photoshop and comparing the centre sections at 300%. There are differences - but also very strong similarities. In particular, it's noticeable in both cases the resolution of pure vertical lines is much worse than for those on the diagonal or on the horizontal, and by what seems to be the same amount. That is true of characteristics with the 700lpph circle as well as the 800lpph.

The difference isn't in actual resolution, but rather that in the FS700 example it goes to plain grey, with the FS100 it goes to aliases. That seems more likely due to differences in OLPF and detail settings - but the likelihood they share the same fundamental sensor, which is something I've previously suspected.

(Matt - I suppose there's no chance you've transposed the labels, is there? I'd expect the FS700 to have a less aggressive OLPF as it is intended to give 4k output in the future - these examples tend to imply the opposite. It also looks as if the detail settings on the FS100 screengrab are higher.)

I appreciate the circumstances you shot these in, but to be more conclusive it would be necessary to have true zone plates (where the frequency varies continuously with distance from the centre) going out to much finer frequencies. If you get the chance, try doing them with camera framed such that the chart only occupies half the width and height of the frame, which will effectively give detail up to 1600lpph.

[Alister Chapman]

Totally different sensor in the FS100 and FS700. The FS700 is 11.6 million pixels compared to the 3.3 million of the FS100.

I keep coming back to the lack of aliasing on the diagonals on the F3 and FS100, also there is no resolution drop as there should be with a traditional bayer sensor. The zone plates should exhibit a distance diamond shape with a conventional Bayer Sensor with the strongest spacial aliases on the diagonals and coloured aliases on H and V, instead what we are seeing is strongest spacial aliases on the H & V and coloured aliases on the diagonals. The diagonal resolution should be half of H and this should be clear to see on these plates being well below 700. Also, while Sony will publish total pixel counts they don't publish H or V pixel counts. I still suspect that the sensors are using a clearvid type rotated array which may explain some of the unusual zone plate characteristics.

Would be nice to see these uncompressed.

[Felix Steinhardt]

Didn´t understand half of that tech talk :)

Now is that a good or bad thing for the FS700?

[Matt Davis]

Originally Posted by David Heath

(Matt - I suppose there's no chance you've transposed the labels, is there?).

LOL, I checked and double checked - no, the labels aren't transposed and yes the giveaway is the extra detail.

Originally Posted by Felix Steinhardt

Didn´t understand half of that tech talk :)

Good for you! Because they do, most of us don't need to. Besides, I'm barely hanging on with my fingernails.

Thanks all - and here's the uncompressed versions, straight from FCPX, which hasn't transcoded the files. (and this is before I unleash the Chroma Du Monde stuff)

[Frank Glencairn]

Originally Posted by Alister Chapman

The zone plates should exhibit a distance diamond shape with a conventional Bayer Sensor with the strongest spacial aliases on the diagonals and coloured aliases on H and V, instead what we are seeing is strongest spacial aliases on the H & V and coloured aliases on the diagonals. The diagonal resolution should be half of H and this should be clear to see on these plates being well below 700. Also, while Sony will publish total pixel counts they don't publish H or V pixel counts. I still suspect that the sensors are using a clearvid type rotated array which may explain some of the unusual zone plate characteristics.

Exactly what I thought Alister, also have a look at this plate by Adam Wilt:

http://provideocoalition.com/images/...00MBSW-024.jpg

Frank

[Felix Steinhardt]

Edit: I see it´s a fluent resolution increase. So how many lines does the FS700 resolve? 900?

[Alister Chapman]

I'd want to do any resolution measurements using MTF50 and Imatest to get consistant figures.

Adams zone plate also show higher diagonal resolution. Given that Sony make their own sensors and they would appear to have mastered clearvid and 45 degree rotated CFA sensors and the interpolation advantages they bring. I don't see any reason why Sony would not use the technology on these cameras.

[David Heath]

Originally Posted by Alister Chapman

Totally different sensor in the FS100 and FS700. The FS700 is 11.6 million pixels compared to the 3.3 million of the FS100.

We've now got direct comparative charts between the F3, FS100 and FS700. For the first two see ProVideo Coalition.com: Camera Log by Adam Wilt | Founder | Pro Cameras, HDV Camera, HD Camera, Sony, Panasonic, JVC, RED, Video Camera Reviews , for similar charts on the FS700 see ProVideo Coalition.com: Camera Log by Adam Wilt | Founder | Pro Cameras, HDV Camera, HD Camera, Sony, Panasonic, JVC, RED, Video Camera Reviews .

What strikes me is how similar the charts are between the FS100 and the FS700 - and how different the F3 chart is to both of them. This is especially the case when the hor/vert resolution imbalances are considered for the 100/700, I can't believe it's just a coincidence they are so similar in each case? Taken together with the facts that the FS100 and 700 come from the same factory and have so much else in common, whilst the F3 comes from a different factory and is so different in so many ways (not least being a widely different power consumption from either of the other two) I now think there's little doubt that the F3 has the 3.3 million sensor and the FS100 shares the 11.6 million sensor of the FS700.

Otherwise, why is the FS100 chart not more like the F3 chart, instead of being so similar to the FS700?

The real giveaway is the strong coloured aliasing on the F3 corresponding to around 1300lpph. The numbers and nature (cyan/yellow on hor/vert and magenta/green on diagonals) are precisely what theory would predict from a 3.3 megapixel Bayer sensor. Yet this is largely missing from the FS100/700 - exactly as would be expected from a sensor with a denser photosite count.

I keep coming back to the lack of aliasing on the diagonals on the F3 and FS100, also there is no resolution drop as there should be with a traditional bayer sensor. The zone plates should exhibit a distance diamond shape with a conventional Bayer Sensor with the strongest spacial aliases on the diagonals and coloured aliases on H and V, instead what we are seeing is strongest spacial aliases on the H & V and coloured aliases on the diagonals.

I disagree. With the photosite rows running hor/vert I'd expect the strongest aliases/least resolution on these axes. Look at Adam Wilts review of the EX1 ( ProVideo Coalition.com: Camera Log by Adam Wilt | Founder | Pro Cameras, HDV Camera, HD Camera, Sony, Panasonic, JVC, RED, Video Camera Reviews ) and it's exactly the same.

Contrary to that, look at Alan Roberts review of the Z5/7, which DOES have the photosites lined at 45deg to the horizontal - http://downloads.bbc.co.uk/rd/pubs/w...-Z5_and_Z7.pdf . In that case it's clear that the alias circles are strongest on the diagonals, likewise least resolution on the diagonal.

[David Heath]

Originally Posted by Felix Steinhardt

Edit: I see it´s a fluent resolution increase. So how many lines does the FS700 resolve? 900?

Well, this is the interesting thing. Using Matt's charts, (enlarging the very centre rings) what is so obvious is that the vert resolution (horizontal lines) is much better than the horizontal resolution (ie vertical lines). Looking at the 800lpph circles, the FS700 just goes to grey along the horizontal axis - but resolves quite cleanly on the vertical axis (bottom of ring). Even looking at the 700lpph circles the horizontal axis is compromised to an extent by aliasing - the vertical axis is not.

Consequently, all I'd really be prepared to say is that the FS700 doesn't manage much better than 700lpph in terms of non-aliased horizntal resolution - but easily manages more than 800lpph vertical. I don't understand why there should be this imbalance, but it makes giving any single resolution figure fairly meaningless.

But looking at Matt's chart for the FS100, it's pretty much the same story - no problem with making 800 for vert res, let alone 700. But on the horizontal....... aliasing compromises the 700lpph circles and no chance of 800 !

But the DIFFERENCE with the FS100 is that at 800lpph it shows a high degree of aliasing of vertical lines, unlike the FS700 which just shows grey.

I put that down to them having the same sensor, but maybe the FS700 having a more aggressive OLPF than the FS100?? Matt - sorry for doubting your labelling (and Adams result broadly agree with what you find) :-), but it's not what I'd expect - not if the aim is to enable a 4k output from the FS700 in future.

[Alister Chapman]

I suspect that the similarities between the FS100 and FS700 may have a lot to do with either the codec or the limited signal processing. A big part of the reason why the FS cameras use a lot less power than the F3 is the use of a low power 8 bit DSP compared to the F3's 12 bit DSP. This is also why the FS cameras really struggle with signal overloads and clipping. I know zone plates primarily show up sensor derived issues but poor processing can also lead to aliasing and resolution loss. If the similarities between the FS100 and 700 were as you imply due to the use of the same 11 MP sensor then it stil doesn't explain the poor H resolution.

I see no reason why Sony would lie about the F3 and FS100 using the same sensor and the FS700 using a newly developed sensor.

In addition you can't compare 3 chip clearvid and bayer. The fact that the single chip sensor on the FS100 looks so much like the EX1 which is not Bayer is all the more reason to suspect that the FS100 is not conventional Bayer either, because it should not look like a conventional 3 chip camera. Furthermore 3 Chip clearvid will behave very differently to single chip as there is no gap between the colour samples as with a CFA. 3 chip clearvid will behave much like any conventional 3 chip camera, but with the aliases rotated 45 degrees which is exactly what you see on the Z5. Now with a single sensor clearvid you in effect reduce the H resolution, what happens.... More aliasing on the H axis. Most conventional Bayer cameras exhibit noticeably reduced resolution which results in increased spatial aliasing on the diagonals as the green channel on the diagonal axis only has half of the H axis resolution, Take a look at zone plates for the Canon XF105 and then compare that to the FS100 and they are very different. Look at Adam's diagonal trumpets for the FS cameras. They should not exhibit more resolution than H or V with Bayer.