I’ve noticed some users concerned or confused by the R and B gain values that they see in the cameras white balance settings after dialling in a custom white balance and tint, or after taking a white balance from a white card. The R and B gain values indicate the offset that is being applied to the Red and Blue channels relative to the Green channel and in fact they are perfectly normal.
Typically the concern occurs when someone has used a white card to set their white balance and then these seemingly random numbers appear against the Red and Blue gain. But they are not random, they are expected, normal, and not normally something to every worry about.
The FX6 and FX9 are set up such that the indicated Red and Blue gains will only ever both be 0 when the white balance of the camera is at exactly 3200K. At any other white balance there will be an offset to the R and B gain – and that is completely normal. It is these offsets that balance the Red and Blue levels so that the white balance appears correct. At a lower colour temperature you will see a positive blue value and a negative red value. Above 3200K there will be a positive Red value and a negative Blue value. A positive tint value will make both the Red and Blue more positive and a negative tint value will make both the Red and Blue values more negative.
All of this is perfectly normal and perfectly expected. If you have taken a white balance off a white card and then dial in a preset value you might find that the you can’t get the last 2 digits back to a zero.
For example after white balancing off a card you have 3653K but you then try to dial in 3200K, but the closest you can get is 3193K or 3213K. This is because the smallest steps the colour temperature changes in is 20K (on the FX6 above 5640K the steps gradually get larger and larger). But this really isn’t something to worry about 3193K or 3213K are both so close to 3200K that either will do and calibration and temperature differences will mean that the actual variations between different cameras or the camera and a colour meter will be greater than this error anyway. No two cameras will ever be truly identical and differences between lenses will cause add to this normal variation. There is no need to worry about the last 2 digits not being zero’s.
At the end of the day, these tiny differences are not something to worry or be concerned about. But if you do want to return the last digits back to zero you can do this by dialling the white balance all the way down to 2000K.
I’ve just return from the arctic cabins that I use for my Northern Lights Aurora tours following a great trip where the group got to see the Aurora on 3 nights. In this video there is footage from two nights, the 13th and 14th of January.
I recommend watching the video direct on YouTube and on a nice big screen in 4K if you can.
Most of it is real time video, not the time-lapse that is so often used to shoot the Aurora. The Sony FX3 (like the A7S3) is sensitive enough to video a bright Aurora with a fast lens without needing to use time lapse. On the FX3 I used a Sony 24mm f1.4 GM lens, this is a great lens for astro photography as stars are very sharp even in the corners of the frame. The Aurora isn’t something that is ever dazzlingly bright, so you do need to use a long shutter opening. So, often I am shooting with a 1/15th or 1/12th shutter. I have been using the CineEI mode at 12,800 ISO and also using the S-Log3 flexible ISO mode to shoot at 25600 ISO. This isn’t something I would normally do – add gain while shooting S-Log3, but in this particular case it is working well as the Aurora will never exceed the dynamic range of the camera, but the footage does need extensive noise reduction in post production (I use the NR tools built into DaVinci Resolve).
I also shot time lapse with my FX30 using a DJI RS2 gimbal. On the FX30 I had a Sigma 20mm f1.4 with a metabones speedbooster. I shot using S&Q motion at 8 frames per second, this gives only a slight speed up and a more natural motion that time lapse shot at longer intervals. By shooting at 8 frames per second I can use a 1/4 of second shutter and this combined with the FX30’s high base ISO of 2500 (for S-Log3) produces a good result even with quite dim Auroras.
By shooting with S-Log3 you can still grade the footage and this is a quick way to get a time-lapse sequence without having to process thousands of still frames. It also needs only a fraction of the storage space.
In a few days I will be heading off to the north of Norway for my annual trip to shoot the Northern Lights. This year I really do hope to stream the Aurora live.
Aurora captured by my FX3 in 2022.
I’ve tried to livestream the Aurora before, but not really been successful. We go to a very remote location to get away from city lights and light pollution. But that means the cellphone connection isn’t great. And then I have had issues with getting the streaming hardware to work correctly in the extreme cold, it’s often well below -20c. I really want to stream the output of my FX3 rather than shooting the back of the camera with a phone as I have done before. Hopefully I will actually succeed this time. There have been some major updates to the software on my Xperia Pro phone and now the HDMI input app includes rtmp streaming direct from the app, so now I can stream from the FX3 via HDMI and the Xperia Pro more easily than before.
The next big unknown is when will the Aurora be visible. To see the Aurora I need clear skies and then the Aurora has to actually be present. There is no guarantee that it will be visible and I certainly can’t predict exactly when. So – I can’t tell you when I will be live. Most likely it will be sometime between January 12th and January 22nd, after 16:00 GMT and before 02:00 GMT. I may be live many times on different nights.
I will also be on facebook and this would be a good way to keep updated as I will try to post on facebook prior to going live on YouTube.
As well as the FX3 I’m taking an FX30 and it will be interesting to see how this performs trying to shoot the Aurora. Main lenses for the Aurora will be the Sony 24mm f1.4 GM, 20mm f1.8 G but I will also have a Sigma 20mm f1.4 with metabones speedbooster for the FX30.
If you are using Zebras to measure the exposure of a log gamma curve you should consider using a narrower Zebra window.
Why?
From middle grey to white (50% to 90%) in the world of standard dynamic range Rec-709 each stop occupies approximately 16% of the recording range. Typically the default zebra window or zebra range used by most cameras is 10% (often +/- 5%). So, when Zebras are set to 70% they will appear at 65% and go away at 75%. For Rec-709 and most conventional SDR gammas this window or range is around 3/4 of a stop, so less than 1 full stop and generally reasonably accurate.
But if using most Cineon based log curves, such as Sony’s S-Log3, between middle grey and white (41% to 61%) each stop only occupies around 8% of the recording range, half the range used by Rec-709. As a result if you use a default 10% zebra window, zebras will appear over a 1.2 stop range, this is excessive and introduces a large margin of exposure error. Compared to Rec-709 the zebras will only be half as precise, especially if you are trying to measure the brightness of a grey card or white card.
I recommend reducing the width of the Zebra window to 6% when using Zebras to measure skin tones within the S-Log3 image (if measuring a Rec-709 LUT there is no need to change the window). This will then give a similar range and accuracy to a 10% window in 709. If you are using zebras to measure a white card or grey card then consider bringing the zebra window down to 2% to gain a more accurate reading of the white/grey card.
FX6(left) and FX3 (right) zebras set to measure S-Log3 white card exposure.
The zebra window or range can normally adjusted in the cameras menu under the zebra settings. On the Sony Alpha’s and and FX3/FX30 you can adjust the range of the C1 and C2 custom zebras.
When you have millions of pixels on a video sensor it isn’t surprising to find that every now and then one or two might go out of spec and show up in your footage as a white dot. These “hot” pixels are most commonly seen when using high ISO’s or the upper of the cameras two base ISO’s. Hot pixels are not uncommon and they are not something to worry about.
The Fix:
Thankfully the issue is easily resolved by going to the cameras main menu and – Setup Menu – Setup Option – Pixel Mapping. Then cap the lens or cap the camera body and run the pixel mapping. It only takes around 30 seconds and it should eliminate any white, black or coloured sensor pixel issues. The camera will ask you to do this periodically anyway and you should do it regularly, especially after flying anywhere with the camera.
Sensor pixels can be damaged by energetic particles that come from cosmic events. So a hot pixel can appear at any time and without warning. They are not something to worry about, it is normal to get some bad pixels from time to time over the life of a camera. When you travel by air there is less of the atmosphere to protect your camera from these particles, so there is a higher than normal likelihood of one going out of spec. Polar air routes are the worst as the earths magnetic field tends to funnel these particles towards the north and south poles. So, whenever you fly with your camera it is a good idea to run Pixel Mapping (or APR if you have an FX6, FX9 etc) before you start shooting.
The XAVC family of codecs was introduced by Sony back in 2014. Until recently all flavours of XAVC were based on H264 compression. More recently new XAVC-HS versions were introduced that use H265. The most commonly used versions of XAVC are the XAVC-I and XAVC-L codecs. These have both been around for a while now and are well tried and well tested.
XAVC-I
XAVC-I is a very good Intra frame codec where each frame is individually encoded. It’s being used for Netflix shows, it has been used for broadcast TV for many years and there are thousands and thousands of hours of great content that has been shot with XAVC-I without any issues. Most of the in flight shots in Top Gun Mavericks were shot using XAVC-I. It is unusual to find visible artefacts in XAVC-I unless you make a lot of effort to find them. But it is a high compression codec so it will never be entirely artefact free. The video below compares XAVC-I with ProResHQ and as you can see there is very little difference between the two, even after several encoding passes.
XAVC-L
XAVC-L is a long GOP version of XAVC-I. Long GoP (Group of Pictures) codecs fully encode a start frame and then for the next group of frames (typically 12 or more frames) only store any differences between this start frame and then the next full frame at the start of the next group. They record the changes between frames using things motion prediction and motion vectors that rather than recording new pixels, moves existing pixels from the first fully encoded frame through the subsequent frames if there is movement in the shot. Do note that on the F5/F55, the FS5, FS7, FX6 and FX9 that in UHD or 4K XAVC-L is 8 bit (while XAVC-I is 10 bit).
Performance and Efficiency.
Long GoP codecs can be very efficient when there is little motion in the footage. It is generally considered that H264 long GoP is around 2.5x more efficient than the I frame version. And this is why the bit rate of XAVC-I is around 2.5x higher than XAVC-L, so that for most types of shots both will perform similarly. If there is very little motion and the bulk of the scene being shot is largely static, then there will be situations where XAVC-L can perform better than XAVC-I.
Motion Artefacts.
BUT as soon as you add a lot of motion or a lot of extra noise (which looks like motion to a long GoP codec) Long GoP codecs struggle as they don’t typically have sufficiently high bit rates to deal with complex motion without some loss of image quality. Let’s face it, the primary reason behind the use of Long GoP encoding is to save space. And that’s done by decreasing the bit rate. So generally long GoP codecs have much lower bit rates so that they will actually provide those space savings. But that introduces challenges for the codec. Shots such as cars moving to the left while the camera pans right are difficult for a long GoP codec to process as almost everything is different from frame to frame including entirely new background information hidden behind the cars in one frame that becomes visible in the next. Wobbly handheld footage, crowds of moving people, fields of crops blowing in the wind, rippling water, flocks of birds are all very challenging and will often exhibit visible artefacts in a lower bit rate long GoP codec that you won’t ever get in the higher bit rate I frame version.
Concatenation.
A further issue is concatenation. The artefacts that occur in long GoP codecs often move in the opposite direction to the object that’s actually moving in the shot. So, when you have to re-encode the footage at the end of an edit or for distribution the complexity of the motion in the footage increases and each successive encode will be progressively worse than the one before. This is a very big concern for broadcasters or anyone where there may be multiple compression passes using long GoP codecs such as H264 or H265.
Quality depends on the motion.
So, when things are just right and the scene suits XAVC-L it will perform well and it might show marginally fewer artefacts than XAVC-I, but those artefacts that do exists in XAVC-I are going to be pretty much invisible in the majority of normal situations. But when there is complex motion XAVC-L can produce visible artefacts. And it is this uncertainty that is a big issue for many as you cannot easily predict when XAVC-L might struggle. Meanwhile XAVC-I will always be consistently good. Use XAVC-I and you never need to worry about motion or motion artefacts, your footage will be consistently good no matter what you shoot.
Broadcasters and organisations such as Netflix spend a lot of time and money testing codecs to make sure they meet the standards they need. XAVC-I is almost universally accepted as a main acquisition codec while XAVC-L is much less widely accepted. You can use XAVC-L if you wish, it can be beneficial if you do need to save card or disk space. But be aware of its limitations and avoid it if you are shooting handheld, shooting anything with lots of motion, especially water, blowing leaves, crowds etc. Also be aware that on the F5/F55, the FS5, FS7, FX6 and FX9 that in UHD or 4K XAVC-L is 8 bit while XAVC-I is 10 bit. That alone would be a good reason NOT to choose XAVC-L.
This is the 3rd and final LUT in the free three LUT set I promised by the end of 2022. Incandescent goes with my Elixir and Solitude LUT’s to complete the set of 3 film style LUTs. Elixir is the base LUT with a neutral film style look, the second LUT is called Solitude which provides a cooler, stark look. Incandescent provides a pleasing warm look, perhaps for feel good or romantic scenes. It might even be a good choice for a happy Christmas look or feel. To download this new LUT go to my LUT page where you will find a wide selection of free LUT’s.
This LUT set can be used with any Sony camera that shoots S-Log3 with SGamut3.cine. So they are perfect for the FX30, FX3, FX6, FX9, Venice as well as the A7S3 etc.
If you find my LUT’s useful please spread the word and link to my Free LUT page so that others can also benefit. More LUT’s will be coming next year.
Bright Tangerine are a UK manufacturer of very high quality camera accessories such as matte boxes, base plates etc. They are based not far from me and I have know them for many years. They also happen to be a sponsor of this site. They may not be a company that some of you have come across before as traditionally their products have been aimed at high end users of cameras such as Venice as well as the Arri and Red digital cinema cameras. But they are now producing some very nice products for lower cost cameras such as the Sony FX6.
Starting at the top of the camera we have a very nice top plate with an optional center section. The center section as well as the sides sections of the cheese plate are all Nato rail compatible and you can attach a Nato rail handle should you wish to use a different handle to the sony one. Like the majority of Bright Tangerine products the 1/4″ and 3/8″ holes are fitted with stainless steel inserts and are surrounded by holes to the Arri anti-rotate standard.
Optional top center nato rail section for the FX6Bright Tangerine top cheese plate for the FX6.
Moving to the side of the camera there is the option to attach a side plate to the top plate. This side plate provides plenty of mounting space for things like radio mics or timecode boxes. It is mounted sufficiently far from the side of the camera body that the SDi and HDMI connectors are still easily accessible but not so far out that it gets in the way with the handgrip.
Bright Tangerine side cheese plate for the FX6
Viewfinder attachment and bracket.
Bright Tangerine make a very nice viewfinder bracket that replaces the Sony one as well as a support system for the LCD screen that eliminates the sagging issues that typically occurs if you want to add a loupe or magnifier to the LCD screen. The LCD bracket uses a clever folding nato rail design that makes it easy to move the mounting point forwards and backwards as well as up and down.
Bright Tangerine AXL Viewfinder bracket for the FX6AXL viewfinder bracket showing how it folds making it highly adjustable.
As well as attaching to the Sony handle the mount has an extra support piece that goes down to the Bright Tangerine top cheese plate. This extra support piece not on helps to support the LCD bracket but it also helps to stabilise the Sony handle.
An additional support bracket goes between the AXL and the Bright Tangerine top cheese plate.
Viewfinder support System.
The viewfinder support system includes a frame that the LCD attaches to that has a fluid damped tilt mechanism. An easy to grip orange knob is used to adjust the tilt tension of the viewfinder.
The Bright Tangerine support system for the FX6 LCD.
When supported by this bracket it is very easy to use an additional viewfinder magnifier or loupe. One of the nice features of the Bright Tangerine FX6 viewfinder support is that it still allows the LCD to be folded flat against the side of the camera when it is not in use.
Left Field Base Plate.
Moving to the bottom of the camera and we have the Bright Tangerine Left Field base plate system. This is quite different to most other base plates. It doesn’t use a VCT plate and as a result it doesn’t suffer from the almost inevitable slight play and wobble that comes with most VCT based systems (perhaps the only exception to this is the Chrosziel QuickLok plate). Instead of using a VCT plate it mates with a standard sized Arri dovetail plate or with Bright Tangerines own light weight dovetail plates.
Bright Tangerine Left Field Base Plate
The Left Field has a very secure clamping system that uses a single lever to clamp and release the plate from the dovetail quickly and easily. When releasing there is an initial lock catch that is released to open the latch and at that point the base can be slid along a normal dovetail plate but won’t lift off or fall off it. To fully release there is a second push button at the base of the release lever that allows the clamp to be completely released and then the camera just lifts off the dovetail.
Left Field release catch.
Once you have used it a couple of times you can release the camera in one single motion by pressing the release button as you open the catch. But it can’t accidentally come undone. To attach the camera to a dovetail you simply slot it on to the far side of the dovetail, and then close the catch, it’s very quick and very easy. The Left Field system creates a very low profile, very stable mounting platform for you camera. Being low profile, when using a tripod it keeps the cameras center of gravity lower allowing you to use less counterbalance and keeps the lens closer to the tilt pivot point.
If you want to add a shoulder pad, one of Bright Tangerines very clever Kasbah pads can be attached to the back of the plate via a quick release bracket. The Kasbah pad is constructed out of a special material that allows the internal structure to be varied to allow for differing levels of firmness across the pad. This makes it very comfortable while offering very stable shoulder support.
BUT when the Kasbah pad is mounted to the rear of the very low profile Left Field it won’t then go on to a normal dovetail as the pad gets in the way. So, you have 2 options. One is to only mount the shoulder pad under the Left Field as and when you need it. The top of the Kasbah pad has a small Arri dovetail so it is very quick to attach to the Left Field. The other option is to use a small riser that raises the Left Field and shoulder pad clear of the dovetail.
Left Field base plate with Kasbah shoulder pad and riser on a full size Arri style dovetail.
One of the great things about the Left Field system is that should you ever change camera all you need to replace is a small mounting adapter that inserts into the top of the Left Field base plate. These means the same Left Field can be used with many cameras, protecting your investment.
A replaceable insert allows the Left Field to be used with a wide range of different cameras.
I really like the bright Tangerine products. They are a little bit different, quirky perhaps. But it’s only by thinking outside of the box that we get new products that really do work. So, if you are looking for a cheese plate, base plate or LCD support system for your FX6 do at least take a looks at their offerings.
Sorry about the temporary outage today. The SSL certificate for the site needed to be renewed, a process that normally happens automatically. But the company that normally issues the certificates appears to be having issues, so I had to get a certificate from a different provider. Running this site does take quite a lot of time and I couldn’t do it without the support of my current site sponsors Bright Tangerine and Camrade. Please do visit their websites if you need camera rigging and support accessories or covers to protect you valuable equipment investment. I highly recommend their products. Not just because they help me run this site, but also because they do make genuinely great products.
I have updated my guide to the FX6’s CineEI mode to ensure it is up to date and compatible with any changes introduced in the Version 3 firmware update. The revised and updated guide includes new graphics that I hope will make the CineEI mode easier to understand for those completely new to shooting S-Log3 and the Sony FX6.
If you are struggling to get to grips with CineEI in the guide I take a step by step approach to using S-Log3 on it’s own without any LUT’s or EI offsets, then introducing the s709 LUT at the base EI and then show how you use different EI levels to offset you exposure. There are suggested exposure levels for both white and grey cards as well as skin tones.
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