Tag Archives: PXW-FX9

FX9 Green Fringing and White Balance Update From Sony Japan.

I had a long, very in depth and very interesting web meeting with several members of the FX9 engineering team in Japan last week. They have been looking into the green fringing that some FX9 users have been reporting in various user groups. I have to say that this hasn’t been something that I have found to be a problem, but if you keep on reading you’ll find out why that is!

The first thing that became very clear in the discussion was that they take issues like this extremely seriously. The FX9 is their baby and they want end users to be happy with it. I was shown a lot of examples of very carefully executed tests using calibrated light sources, test charts, and various objects with different colours or reflectivity placed in extreme contrast situations.

And yes, in some cases the images would show a green edge around the high contrast edge of an extremely backlit object. Not just with the FX9 but also with the FS7 they were comparing it against.

The cause is Chromatic Aberration in the lens.

In every case the cause of the coloured edge is chromatic aberration. Chromatic aberration is an optical phenomenon cause by the way the glass in a lens will inevitably refract different wavelengths of light (and thus different colours) by different amounts. So when one colour is in precise focus, other colours may be slightly out of focus and this causes blurring of one colour and this typically manifests itself as a blue, green or red fringe – chromatic aberration.

So the root cause of this issue is not the camera, it is the lens and it will vary from lens to lens. But do keep reading – there is more you need to know…….

Other Factors.

However there are other factors at play. One is the way a bayer sensor works. There is a huge resolution difference between the green channel and the red and blue channels. A lot of complex processing is used to compensate for this and that processing is optimised for what you might call “normal” or “typical” scenes. So when presented with a shot that has extreme contrast and a lot of optical chromatic aberration sometimes this processing isn’t going to deliver a fully optimised image and it may reveal the differences in resolution between the 3 colour channels. This is particularly the case with green CA as the green channel has much greater resolution than the others. 

But the FS7 doesn’t do it….

But this bayer/processing issue will be broadly similar between the FX9 and FS7, so why are more FX9 owners reporting a problem than FS7 owners?

The answer it seems is white balance!

All the  reports of this issue have occured when the camera has been set to a daylight white balance, most of the time it has been when the camera has been set to it’s default 5500K daylight preset.

When comparing the FX9 with the FS7 with both set to 5500K the FX9 has a small but noticeable bias towards green. I and many others have been aware of this from the launch of the camera, especially when you use the camera in the CineEI mode and use the standard s709 LUT from Sony. The images are distinctly more green than any other Sony camera and a fair bit more green than the FS7, FS5 and Alphas.

It’s not that white objects won’t be white, it’s just that overall the image looks a bit green. This is easily dialed out by adding a +20 offset to the cameras tint control and that is how I have been using my camera pretty much from day one.

When you think about it – or when you analyse the situation carefully as Sony have, if the camera has more green, what will happen if you have green CA? Well it’s going to be much more pronounced.  And that is what we are seeing. The way the colours in the FX9 are tuned has an unfortunate side effect of making green CA much more obvious.

This explains why I have never really had an issue with green CA. I’m normally running a +20 tint offset which reduces the green in the camera plus I tend to use my own less green versions of the s709 LUT or I use ACES which is also less green than Sony’s own s709 LUT. So overall I have already dialed out the green and unknowingly fixed an issue I didn’t know I had.

So the engineers in Japan are currently recommending adding a +20 tint to the camera when shooting daylight. In particular instead of using a preset of 5500K to use 5000K and +20 tint to achieve the same white balance but a less green image. They are also assessing whether the camera needs to have it’s processing adjusted so that it is less green when using the 5500K preset. At warmer colour temperatures this issue does not seem to ever be a problem, it’s only with daylight.

Push Auto White Balance.

Further to this it’s also worth noting that if you use the cameras Push Auto white balance to set the white balance with a white or grey card then this will normally deliver the optimum white balance for the scene you are shooting and it won’t be biased towards green. And we should remember that Push Auto white balance works correctly in both the CineEI mode and Custom mode. If you use Push Auto WB there is no need to add a +20 Tint and the pictures should look natural and well balanced. Having become used to using preset white balance values when shooting S-Log with Sony cameras for so many years I keep forgetting that you can now do this. 

Another benefit of Push Auto WB is that as it balances the camera correctly it also helps bring the FS5, FS7, F55 etc and FX9 closer together if you are using a mix of different cameras. I was recently shooting with a Venice and FX9 side by side and by using the Push Auto WB on both Venice and the FX9 it became extremely hard to tell one from the other. Previously when using the presets the FX9 always looked a touch green.

Also – if you are using daylight balanced LED or fluorescent lights using Push Auto white balance will help correct out any tendency towards green that the lights may have. So really Push Auto White Balance is a win-win situation and let’s face it a lot of you have been asking for it in CineEI for a long time – so now we have it, let’s use it.

What about Aperture Correction?

In my own experiments I found that in Custom Mode turning off the cameras Aperture correction (http://www.xdcam-user.com/2020/07/reducing-ca-artefacts-in-the-sony-fx9/) can help reduce the visibility of the CA. As CA is an optical edge effect, anything that enhances edges will also enhance the CA and turning off aperture correction prevents the CA from being boosted by the aperture correction. Overall I personally prefer the images you get from the FX9 with aperture correction off anyway, they are a little bit less sharp and more rounded. 

And slightly off topic, what about image quality at FF and S35 2K scan? This was discussed as well, the engineers want people to be happy with the camera. The issue is that this is a camera with a 6K sensor and an optical system designed around that 6K sensor. So if you then reduce the resolution of the sensor readout the optics are no longer optimised (mainly the Optical Low Pass Filter). As a result there is an inevitable increase in aliasing and moire. Unfortunately this is just the way the physics works and there is not much that can be done about it. But the engineers know that the FX9 will be compared with the FS7 – which also has similar issues in it’s S35 2K scan modes. The goal of the engineers is that the FX9 should not be worse than the FS7 and there are some tweaks in the pipelines to the image processing that will bring some improvements to the FX9 when using 2K scan. But let’s be realistic, this will always be a camera with a 6K sensor and a 6K OLPF, so the Full Frame and Super 35mm 2K scan modes will never match the quality of the 6K and 4K scan modes, it just isn’t possible so don’t expect miracles. These tweaks may take a bit of time to be finalised, so I’m not sure when we will see them. I think what we should see however is the 2K scan from an FX9 being indistinguishable from the 2K scan of an FS7.

PXW-FX9 Exposure Accuracy – Can I use A Light Meter?

This came up during a Facebook discussion. Can you use a light meter with the FX9 and will the exposure be correct?

When I first met the FX9 at Sony’s Pinewood Studios facility we tested and checked all sorts of different aspects of the cameras performance against various light meters and test charts. I found that the camera matched what we expected perfectly well.

But just to be sure I have just tested my own example against my trusty Sekonic light meter and once again I am happy to say that everything seems to match as expected.

In this simple setup I used a couple of different charts with middle grey and 90% white – I do find that there is some variation between charts in how reflective the 90% and 18% reflectivity areas are. So I’ve used a couple here and my main reference is the large DSC Labs white and middle grey chart.

I used the dimmers on my lights so that my metered exposure reading for 24fps 1/48th shutter came to exactly f5.6. Then I set the lens to f5.6 (Sony 24-70mm GMaster).

The result is pretty much as close to a perfect exposure as one can expect. So don’t be afraid to use a light meter with the FX9.

Screenshot-2020-07-21-at-10.11.45-1024x648 PXW-FX9 Exposure Accuracy - Can I use A Light Meter?
Exposed via the light meter, screen grab from Catalyst Browse.

 

Screenshot-2020-07-21-at-10.14.53-1024x543 PXW-FX9 Exposure Accuracy - Can I use A Light Meter?
And the levels as measured in DaVinci Resolve. All looks good and where you would expect S-Log3 to be.

Reducing CA Artefacts In The Sony FX9.

I’ve been experimenting a bit trying to reducing the effect of Green/Cyan CA with the FX9. I have discovered a couple of things that can help reduce interactions between the cameras processing and areas of high contrast that may be exhibiting bright green/cyan fringes.

First thing to note is that a lens with less or no CA will not have the same issue. But as no lens is totally CA free the below settings can help.

These changes are for Custom Mode Only.

1: Turn OFF the aperture correction in the paint menu. Turning off the aperture correction noticeably reduces the cameras tendency to create black halos in areas of extreme contrast and it also reduces the enhancement of areas of strong CA. This has a softening/smoothing effect on bright CA making it much less noticeable. There is very, very little loss of sharpness in the rest of the image and I actually prefer the way the camera looks with this turned off.

2: Use the Multi-Matrix to reduce the brightness of Green/Cyan CA. The most common examples of CA causing an issue are with background out of focus high contrast areas. In this case the CA is normally Green/Cyan. It’s possible to tune the cameras multimatrix to reduce the brightness of these green/cyan edges. If you turn ON the mutli-matrix and then select CY+ and set this to -30 you will see a very useful reduction in the intensity of the CA. For a stronger reduction in addition select CY and set this to -15. 
Changing these setting will have an impact on the reproduction of other cyan objects in your shots, but you should see this in the VF and testing various scenes these changes are typically not noticable. In some cases I am finding I actually like this slightly modified look!

Use both of the above together for the strongest impact. But if you are only going to use one, turn off the aperture correction.

Without-adjustments_1.2.1-1024x576 Reducing CA Artefacts In The Sony FX9.
CA on over exposed areas with no corrections (400% zoom)

 

With-Aperture-Off-CY-adjust_1.1.1-1024x576 Reducing CA Artefacts In The Sony FX9.
With Aperture turned OFF and the CY+ set to -30 (400% zoom)

Rigging the PXW-FX9

In case you missed the live stream I have uploaded the recording I made of my almost hour long video with hints, tips and ideas for rigging the PXW-FX9. In the video I cover things like base plates including VCT and Euro Plate. I look at hand grip options, rod rails and matte boxes as well as power options including V-mount adapters and the XDAC-FX9.  Of course everything in the video is based on my own personal needs and requirements but I think there is some good information in there for anyone looking to accessorize their FX9, whether for working from a tripod or handheld.

 

PXW-FX9 User Guide Now Available for FREE Download.

FX9-quick-ref-guide PXW-FX9 User Guide Now Available for FREE Download.
The PXW-FX9 user guide.

 

Sony have released the PXW-FX9 user guide that I wrote for them. The guide is in the form of a searchable PDF designed for reading on a mobile device. The idea being that you can keep it on your phone in case you need to reference it on a shoot. It’s not meant to replace the manual but to compliment it and answer questions such as – what is S-Cinetone?

To download the guide go to the main Sony PXW-FX9 landing page and scroll down towards the bottom. There you should find a link that will take you to the guide download page as well as other resources for the FX9.

https://pro.sony/en_GB/products/handheld-camcorders/pxw-fx9

The PXW-FX9 is NOT made out of plastic.

I’ve been quite surprised by the number of people out there that seem to think the PXW-FX9 is made out of plastic. It isn’t. It’s made from an incredibly strong material call magnesium alloy. This metal is stiffer and stronger than aluminium. It’s highly impact and corrosion resistant but still extremely light. There are only a couple of places where plastic is used, one being the cover over the WiFi antenna where a metal cover would block the wireless signals. Here are some pictures of the FX9’s chassis. Note the box shaped areas used to isolate the electronics from the air that flows through the camera to ensure the electronics are weather sealed. Also note all the ribbing and reinforcing on the inside at the front of the camera where the lens mount an sensor block are attached keep it all very solid.

DSC_0352-1024x576 The PXW-FX9 is NOT made out of plastic.DSC_0353-1024x576 The PXW-FX9 is NOT made out of plastic.DSC_0354-1024x576 The PXW-FX9 is NOT made out of plastic.

Using User Files and All Files to Speed Up Switching Modes on the FX9.

Sometimes changing modes or frame rates on the FX9 can involve the need to change several settings. For example if you want to go from shooting Full Frame 6K at 23.98fps to shooting 120fps then you need to change the sensor scan mode before you can change the frame rate. One way to speed up this process is to use User Files or All Files to save your normal operating settings. Then instead of going through pages of menu settings you just load the appropriate file.

All Files save just about every single adjustable setting in the camera, everything from you white balance settings to LUT’s to Network settings to any menu customisations.  User Files save a bit less. In particular User Files can be set so that they don’t change the white balance. For this reason for things like changing the scan mode and frame rate I prefer to use User Files.

You can add the User File and/or All File menu items to the user menu. If you place them at the top of the user menu, when you enter the cameras menu system for the first time after powering it on they will be the very first items listed.

Both User Files and All Files are found under the “project” section in the FX9 menu system. The files are saved to an SD card in the SD Card Utility slot. This means you can easily move them from one camera to another.

Before you save a file, first you have to give it a name. I recommend that your name includes the scan mode, for example “FF6K” or “2KS35”, the frame rate and whether it’s CineEI or not.

Then save your file to the SD card. When loading a User File the “load customize data” option determines whether the camera will load any changes you have made to the user menu. “Load white data” determines whether the camera will load and overwrite the current white balance setting with ones saved in the file. When loading an All File the white balance and any menu customizations are always loaded regardless, so your current white balance setting will be overwritten by whatever is in the All File. You can however choose whether to load any network user names and passwords.

FX9 footage from Norway 2020

Here’s a compilation of footage from this years winter trip to Norway. This was all shot with the PXW-FX9. Mostly with sony lenses and autofocus. The AF was great for following the dog sledding. The camera performed really well and did a great job of capturing what was a very faint Aurora display in between cloud banks.

The daytime footage was shot using S-Log3 in CineEI. I didn’t expose any brighter than base, so used 800EI or 4000EI. I used the viewfinder display gamma assist rather than any LUT’s as I know I can use gamma assist no matter what frame rate I shoot.

DSC_0899-1024x768 FX9 footage from Norway 2020
The PXW-FX9 worked perfectly even when the temperature was below -30c.

The Aurora was very faint, barely visible to the naked eye, so I had to shoot using a 32 frame slow shutter (the equivalent of about 1.3 seconds at 24fps). I then used interval record with a 2 second interval to create the timelapse Aurora sequences.  As there were no dynamic range concerns I chose to shoot using the default S-Cinetone settings in custom mode so I could see exactly what I was getting. I was amazed at how many stars the camera picked up with such a short exposure, a sure sign of how sensitive the camera is. For the Aurora I used a Sigma 20mm f1.4 lens with Metabones speed booster and 4K s35 scan. I felt that the extra stop of light gained from the use of the speedbooster was better than the slightly lower noise that would have been present if I had used the 6K FF scan. I did also try S&Q at 1 frame per second with the shutter off to see how this compared to the slow shutter. The S&Q was much noisier, the cameras built in NR seems to work particularly well with the slow shutter function, so if you need a long exposure on the FX9 I recommend slow shutter and interval record over S&Q at 1 frame per second.

DSC_0887-768x1024 FX9 footage from Norway 2020For the  sunset shots I made use of the variable ND filter, set to auto to control the exposure. I used the cameras “backlight” auto exposure setting to obtain a bright exposure despite the strong sunlight. These shots were shot using S-Log3 in CineEI and it’s nice that the auto exposure functions work very well in this mode. The main lens used was a Sony 24-240mm f3.5-f6.3 zoom. Not the very greatest of lenses, but for such a zoom range the image quality is pretty decent. I used this lens because the temperature was often below -15c dipping to -34c at times. In addition there was a lot of blowing snow. I don’t like doing a lot of lens swapping in these conditions and the 24-240mm allowed me to take just one lens on most of the trips out and about on the snow scooters or dog sleds.

DSC_0856-1024x768 FX9 footage from Norway 2020
Getting ready to go and shoot with the FX9 plus Core V-Mount adapter and Core Neo 98Wh battery.

Another big help was the Core SWX V-Mount adapter. I used both the Core Neo 98Wh V-Mount batteries and some of my Pag Paglink 150Wh V-Mounts. They all worked very well in the harsh conditions and a great feature of the Core Neo’s is the run time indicator that gives an accurate time remaining readout based on the batteries capacity and the cameras power draw. This is very handy when using a V-Mount adapter as all the adapters currently on the market convert the battery voltage up to 19.5 volts to feed the FX9. As a result you don’t get any form of capacity or run time indication in the viewfinder. The Core V-Mount adapter also incorporates an LED indicator that turns red as the battery voltage gets low and then flashes red when it’s about to run out – a very nice touch. I did use a loose fitting insulated cover that I made myself. It’s not heated but does have a fleece lining so helps keep the heat generated by the camera when it’s operating in the camera. Where this really helps is to keep the lens warmer than the ambient air and this helps stop the lens from frosting over when shooting the aurora at night (see the picture at the top of the article where you can see just how frosty things can get at night).

DSC_0874-768x1024 FX9 footage from Norway 2020
Miller CX16 tripod head and solo legs works extremely well even in very cold conditions.

As usual on these trips we had one guest break a tripod. A lot of materials that are normally solid and robust become very brittle at temperatures below -15c. I was using a Miller CX18 tripod head with Miller Solo legs and once again this proved to be a great combination. The fluid damping of the head remain almost completely constant all the way down to -34c. A lot of other heads become unusable at these sorts of temperatures.

For file backup and file management I use the Nexto DI NPS-10. This is a relatively new device from Nexto DI. Designed to offer a robust backup solution at a much lower price than similar previous Nexto DI products it too worked very well even in these harsh conditions. I have a 1TB SSD in mine and I can backup a 128GB XQD card in around 5 minutes. I can’t recommend the Nexto DI products enough for those that need to have a simple, reliable backup on location.

The workshop shots are part of a sequence of shots for another video I am working on. For these I used Sony 85mm f1.8 FE and 24mm f2 FE lenses. The sequence is mostly available light but I did have a Light & Motion Stella 5K on hand to add a little extra light here and there.

Post production was done using DaVinci Resolve and ACES.

Base ISO Levels for the FX9

First of all. Unless you are actually using a lightmeter to determine your exposure, in custom mode it is far, far easier to use dB of gain. 0dB is always optimum and each time you go up 6dB the picture gets twice as bright (one stop brighter) and the noise doubles. ISO is in most cases nothing more than a rating to use in conjunction with a lightmeter to get the right picture brightness, it will not tell you how much noise you have or whether the camera is at it’s optimum setting. So don’t use ISO just because “ISO is cool and make me sound like I know what I’m doing, it makes me a cinematographer”. This isn’t a film camera, no matter how much you dress it up it is a video camera and dB tells you exactly what it is doing.

Because different gamma curves produce different brightness images the ISO rating will change depending on the gamma curve being used, this isn’t a sensitivity change, it’s an optimum brightness change. Because of this, even when you are at 0dB gain (the native setting) when you switch between different gammas the ISO rating changes. In addition because you have two different base sensitivity modes on the FX9 there are a lot of different base ISO’s (all of which are 0dB gain). I’ve prepared a table of the different base ISO’s.

Screenshot-2019-12-30-at-11.00.53-1024x295 Base ISO Levels for the FX9

In addition if you are not careful it’s possible to end up using too much gain to achieve a certain ISO as many ISO ratings can be realised at both Hi and Low Base sensitivity. You don’t want to be at 2500 ISO in Low Base for example, you would be better off using High base. The table below should help you understand when to switch up to High base from Low base. If you use dB gain, then it’s easy. More than +11dB – switch up. Don’t forget in dB mode you can also go down to -3dB.

Screenshot-2019-12-30-at-12.26.58-1024x342 Base ISO Levels for the FX9