Many people wish to bake in the cameras Exposure Index settings when shooting using CineEI in order to avoid having to make an exposure correction in post production (given that the cameras are ISO invariant when shooting Log in reality it makes vey little difference whether you add gain in the camera or in post production – gain is gain). On cameras such as the FS7, FX6 or FX9 one way to do this is by baking in the built in S-Log3 LUT. To avoid confusion – that is using the CineEI mode with the “S-Log3” LUT enabled and in the LUT settings “Internal recording” set to ON so that you are recording the “S-Log3” LUT.
While this will bake in the EI change, this technique comes with many issues. For a start, just as when you use S-Log3 in custom mode and alter the ISO, whenever you move away from the cameras base ISO you loose dynamic range. When you bake in a LUT and change the EI, you are in effect changing the ISO and there will be a corresponding loss of dynamic range. When you bake in a LUT this loss of dynamic range is exacerbated by a reduced or altered recording range.
At lower EI’s the available recording range shrinks as the LUT is made darker and at the same time upper recoding level of the LUT is reduced. At 200 EI the recording range only gets to around 78%. At the bottom end the shadows are crushed and shadow information lost by the range reduction. This then causes a post production issue because LUT’s designed for the normal S-Log3 input range of 0-94% will now be applied to recordings with a much reduced range and after application of a LUT in post the final output won’t get to 100% without further complex grading where the image will need to be stretched more than normal and this degrades quality.
At high EI’s the LUT becomes brighter but the clip point remains the same. So for each stop you go up, 1 stop of highlights just disappears beyond the LUT’s hard clip point and can’t be ever recorded. Again in post this can cause issues because when you apply a normal S-Log3 LUT the heavy clipping in the recording causes the highlights to look very heavily clipped (because they are). Again, for the best results you will need to grade your footage to allow for this.
So, in practice the idea of baking in the S-Log3 LUT to eliminate the need to do any post production corrections doesn’t work because the addition of the S-Log3 LUT introduces new limitations that will need to be corrected if you want good looking images. Plus adding the S-Log3 LUT in camera and then adding another LUT on top in post is never going to deliver the best results due to the way LUT’s divide the image into brightness zones.
And – if you are baking in the S-Log3 LUT, then really this is no longer EI as there is now no longer an offset between the exposure and the recording, you are simply recording at a higher/lower ISO.
Category Archives: PXW-FS7
Improve the accuracy of manual white balance with the FX6 and FX9.
Have you ever struggled to get a decent white balance from a white or grey card with the Sony FX6, FX9 or in fact many other cameras (this method works equally well for the FS7, FS5, F5 and F55 etc)? Well here is a very simple trick that can really help, especially for those situations where the camera is a long way from the scene and a white card is too small in the frame for an accurate reading.
All you need to do is to cut a square hole in a piece of black card or plastic. Then when you want to take your white balance simply hold the mask in front of the lens so that it masks out the background of the shot leaving just your white card visible. It’s really simple, really easy and it really works!
New LUT for Sony cameras and S-Log3 – Elixir
I’ve added a new LUT for S-Log3 and SGamut3.cine to my free LUT collection. The new LUT is called Elixir and is the first LUT from a collection of 3 new LUTs with similar contrast and brightness but quite different colours that I will be releasing between now and the end of the year. Elixir is designed for short film projects and drama to provide rich colours with pleasing skin tones. Blues are shifted slightly teal, but there is no distracting colour cast, just pleasing colours with mid to high contrast. The LUT can be used with any Sony camera that has S-Log3 and SGamut3.cine, so that includes the whole of the Cinema Line including the FX6, FX3 and FX30 as well as cameras like the FS5 and FS7. For more information and to download this or any of my free LUTs please go to the LUT page: https://www.xdcam-user.com/picture-settings-and-luts/alisters-free-luts/
Removing Screws From Sony Cameras
Although I wouldn’t normally recommend removing the screws from Sony cameras there are times when this is something you need to do, for example to remove the microphone mount on an FX6.
Most of the small screws have a thread locking compound applied to the threads to prevent them from shaking or vibrating loose. This can make them hard to unscrew.
JIS NOT Phillips!!
The main issue is that most cross of the commonly found small and miniature head screw drivers are manufactured to the “Philips” standard. But the screws used on the Sony cameras are manufactured to the JIS standard. The differences between these two very similar looking standards means that you will not get a secure and tight fit between a Philips screw driver and a JIS screw head. The edges of a Philips screwdriver are at an angle that is too shallow to properly engage with the full depth of a JIS screw head. So when you try to undo a tight screw the head of the screw will deform or strip, often to the point where it can’t be undone.
Whenever working on Sony cameras you should use JIS standard screwdrivers and ensure the screwdriver is the correct size for the screws you are working with. The smaller screws used for thing like the microphone mount on the FX and Alpha series cameras are JIS size +0 or +00. A JIS size +0 seems to fit most but I would also get a +00.
Don’t try to use a miniature Philips screwdriver on a tight JIS screw. It might look like it fits, but only a very small part of the screwdriver head will be correctly engaged with the JIS screw and once the screw head is damaged you can’t undo the damage and it may become impossible to remove the screw without drilling it out.
If you search for “Vessel JIS” you should be able to find good quality small and miniature JIS screwdrivers on Amazon, ebay or from other suppliers.
Using Auto Exposure With Cine EI.
First – What is “Exposure”
Something I find useful to consider is that “Exposure” is the amount of light that you put onto the sensor or film stock in your camera. It isn’t brightness, it is how much light. If you think about it, if you use a light meter to find you exposure settings, the light meter has no idea how bright the pictures will be, all it does is give you the shutter and aperture values needed to put the correct amount of light onto the sensor or film stock.
How Cine EI Works.
Next we need to think about how Cine EI works. You have to remember that when shooting using Cine EI the only thing that changes when you change the EI value is the brightness of the LUT and it is also worth considering that different LUTs may be completely different brightness. There is no change to the sensitivity of the sensor and no direct change to the brightness of what is recorded. To change the brightness of what is recorded YOU must change the aperture, shutter speed or ND etc. Normally you would monitor your images via a LUT and then you must adjust the exposure so the image on the viewfinder looks correct at the new Exposure Index, or use the waveform to measure the LUT and use this to set the exposure for the new EI. And by changing the exposure you are adding an exposure offset putting more (or less) light on to the sensor than would be normal at the base EI.
AE In Cine EI.
If you wish to use auto exposure in the Cine EI mode then you need to understand that the camera’s auto exposure system measures what is being recorded. It does not measure the LUT levels. The auto exposure system is unaware of your desire to expose the sensor more or less brightly than normal and will always base the exposure on the base ISO, not the Exposure Index. As a result if you are using AE and you go from 800 EI to 400 EI the image seen via the internal LUT will get darker by one stop, the AE will NOT compensate for the lower EI. If you were to manually brighten the exposure by one stop the cameras exposure meter will think you are now over exposed – because you are!
Adding Offsets.
The only way around this is to add an offset to the AE system to account for the offset added by the different Exposure Index. For example if you want to shoot at 400EI (The LUT becoming 1 stop DARKER) then you would need to add a +1.0 stop offset to the cameras AE settings to offset the exposure 1 stop brighter. Each time you halve the EI you should add an extra +1 stop of offset. Each time you double the EI you should include an extra -1 stop offset.
There are a couple of ways to do this but the quickest is to use the Quick Menu function that is by default assigned to button 5 on the hand grip or button 8 on the handle. Press the direct menu button and then use the thumbstick to go the AE+0 indication just above the shutter speed indicator and add your offset.
Or you can long press the menu button to go into the cameras main menu then go to the – Shooting – Auto Exposure page and add your offset to the Level setting.
I don’t recommend the use of Auto Exposure in Cine EI. For a start AE uses the average brightness of the scene to set the exposure level, often this isn’t appropriate for Log. When shooting with log generally you want to ensure that it is your mid range is exposed at the right level and you don’t want bright highlights to result in an under exposed mid range. Additionally if the exposure changes mid shot this can make grading very difficult. If you do use auto exposure in Cine EI, then as well as adding any necessary offsets I also recommend slowing down the responsiveness of the AE using the “Speed” setting in the Auto Exposure menu. Using a value such as -60 will slow down the rate at which the AE will change the exposure which helps avoid rapid auto exposure changes for momentary light changes within the scene.
It is really important to remember that Exposure is NOT brightness. Exposure is how much light you put on the sensor. A light meter doesn’t know how bright you want your pictures to be. All it knows is the correct amount of light to put on to the sensor for the “correct” exposure. If using an external light meter provided you put the right values into your light meter it will give you the correct exposure settings, even though it has no idea how bright your pictures will be and the camera’s internal exposure meter acts in a similar way, so offsets are needed to match each EI you use.
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CineEI is not the same as conventional shooting.
CineEI is different to conventional Shooting and you will need to think differently.
Shooting using CineEI is a very different process to conventional shooting. The first thing to understand about CineEI and Log is that the number one objective is to get the best possible image quality with the greatest possible dynamic range and this can only be achieved by recording at the cameras base sensitivity. If you add in camera gain you add noise and reduce the dynamic range that can be recorded, so ideally you always need to record at the cameras base sensitivity for the best possible captured image.
Sony call their system CineEI. On an Arri camera the only way to shoot log or raw is using Exposure Indexes and it’s the same with Red, Canon and almost every other digital cinema camera when shooting log. You always record at the cameras base sensitivity because this will deliver the greatest dynamic range.
Post Production.
A key part of any log workflow is the post production. Without a really good post production workflow you will never see the best possible results from shooting Log. An important part of the post production workflow will be correcting for any exposure offsets used when shooting. If something has been exposed very brightly, then in post you will bring that exposure down to a normal level. Bringing the levels down in post will decrease noise. The flip side to this is that if the exposure is very dark then you will need to raise the levels in post and this will make then more noisy
Exposure and Light Levels.
It is assumed that when using CineEI and shooting with log that you will control the light levels in your shots and use levels suitable for the recording ISO (base ISO) of the camera using combinations of aperture, ND and shutter speed, again it’s all about getting the best possible image quality. If lighting a scene you will light for the base ISO of the camera you are using.
Here’s the bit that’s different:
Changing the EI (Exposure Index) allows you to tailor where the middle of your exposure range is. It allows you to alter the balance between more highlight range with less shadows or less highlight range with more shadow information in the captured image. On a bright high contrast exterior you might want more highlight range, while for a dark moody night scene you might want more shadow range. Exposing brighter puts more light on to the sensor. More light on the sensor will extend the shadow range but decrease the highlight range. Exposing darker will decrease the shadow range but also allow brighter highlights to be captured without clipping.
IMPORTANT: EI is NOT the same as ISO.
ISO is a measure of a film stock or camera sensors SENSITIVITY to light. It is the measure of how strongly the cameras sensor responds to light.
Exposure Index is a camera setting that determines how bright the image will become for a given EXPOSURE. While it is related to sensitivity it is NOT the same thing and should always be kept distinct from sensitivity.
ISO= Sensitivity and a measure of the sensors response to light.
EI = Exposure Index – how bright the image seen in the viewfinder will be.
The important bit to understand is that EI is an exposure rating, not a sensitivity rating. The EI is the number you would put into a light meter for the optimum EXPOSURE for the type of scene you are shooting. The EI that you use depends on your desired shadow and highlight ranges as well as how much noise you feel is acceptable.
What Actually happens when I change the EI value on a Sony camera?
On a Sony camera the only things that change when you alter the EI value are the brightness of any Look Up Tables (LUTs) being used, the EI value indicated in the viewfinder and the EI value recorded in the metadata that is attached to your clip.
Importantly – To actually see a change in the viewfinder image or the image on an external monitor you must be viewing your images via a LUT as the EI changes the LUT brightness, changing the EI does not on it’s own change the way the S-Log3 is recorded or the sensitivity of the camera. If you are not viewing via a LUT you won’t see any changes when you change the EI values, so for CineEI to work, you must be monitoring via a LUT.
Raising and Lowering the EI value:
When you raise the EI value the LUT will become brighter. When you lower the EI value the LUT will become darker.
If we were to take a camera with a base ISO of 800 then a nominal “normal” exposure would result from using 800 EI. When the base ISO value and the EI value are matched, then we can expect to get a “normal” exposure.
Let’s now look at what happens when we use EI values higher or lower than the base ISO value.
(Note: One extra stop of exposure is the equivalent of doubling the ISO or EI. One less stop of exposure is the equivalent of halving the ISO or EI. So if double 800 EI so you get to 1600 EI this would be considered 1 stop higher. If you double 1600 EI so you are at 3200 EI this is one further stop higher. So 800 EI to 3200 EI is 2 stops higher)
If you were to use a higher EI, let’s say 3200 EI, two stops higher than the base 800 EI, then the LUT will become 2 stops brighter.
If you were using a light meter you would enter 3200 into the light meter.
When looking at this now 2 stops brighter viewfinder image you would be inclined to close the aperture by 2 stops (or add ND/shorter shutter) to bring the brightness of the viewfinder image back to normal. The light meter would also recommend an exposure that is 2 stops darker.
Because the recording sensitivity or base ISO remains the same no matter what the EI, the fact that you have reduced your exposure by 2 stops means that the sensor is now receiving 2 stops less light, however the recording sensitivity has not changed.
Shooting like this, using a higher EI than the base ISO will result in less light hitting the sensor which will result in images with less shadow range and more noise but at the same time a greater highlight range.
A very important thing to consider here is that this is not what you normally want when shooting darker scenes, you normally want less noise, more shadow range. So with CineEI, you would normally try to shoot a darker, moody scene with an EI lower than the base ISO.
This goes completely against most peoples conventional exposure thinking.
For a darker scene or a scene with large shadow areas you actually want to use a low EI value. So if the base ISO is 800 then you might want to consider using 400 EI. 400 EI will make the LUT 1 stop darker. Enter 400 EI into a light meter and compared to 800 the light meter will recommend an exposure that is 1 stop brighter. When seeing an image in the viewfinder that is 1 stop darker you will be inclined to open the aperture or reduce the ND to bring the brightness back to a normal level.
This now brighter exposure means you are putting more light on to the sensor, more light on the sensor means less noise in the final image and an increased shadow range. But, that comes at the loss of some of the highlight range.
Need to think differently.
The CineEI mode and log are not the same as conventional “what you see is what you get” shooting methods. CineEI requires a completely different approach if you really want to achieve the best possible results.
If you find the images are too dark when the EI value matches the recording base ISO, then you need to open the aperture, add light or use a faster lens. Raising the EI to compensate for a dark scene is likely to create more problems than it will fix. It might brighten the image in the viewfinder, making you think all is OK, but on your small viewfinder screen you won’t see the extra noise and grain that will be in the final images once you have raised your levels in post production. Using a higher EI and not paying attention could result in you stopping down a touch to protect some blown out highlight or to tweak the exposure when this is probably the last thing you actually want to do.
I’ve lost count of the number of times I have seen people cranking up the EI to a high value thinking this is how you should shoot a darker scene only to discover they can’t then make it look good in post production. The CineEI mode on these cameras is deliberately kept separate from the conventional “custom” or “SDR” mode to help people understand that this is something different. And it really does need to be treated differently and you really do need to re-learn how you think about exposure.
For dark scenes you almost never want to use an EI value higher than the base ISO value and often it is better it use a lower EI value as this will help ensure you expose any shadow areas sufficiently brightly.
The CineEI mode in some regards emulates how you would shoot with a film camera. You have a single film stock with a fixed sensitivity (the base ISO). Then you have the option to expose that stock brighter (using a lower EI) for less grain, more shadow detail, less highlight range or expose darker (using a higher EI) more grain, less shadow detail, more highlight range. Just as you would do with a film camera.
Sony’s CineEI mode is not significantly different from the way you shoot log or raw with an Arri camera. Nor is it significantly different to how you shoot raw on a Red camera – the camera shoots at a fixed sensitivity and any changes to the ISO value you make in camera are only actually changing the monitoring brightness and the clips metadata.
Exposing more brightly on purpose to achieve a better end result is not “over exposure”. It is simply brighter exposure. Over exposure is generally considered to be a mistake or undesirable, but exposing more brightly on purpose is not a mistake.
Should You Use In Camera Noise Reduction Or Not?
This is another common question on many user groups. It comes up time and time again. But really there is no one clear cut answer. In a perfect world we would never need to add any noise reduction, but we don’t live and shoot in a perfect world. Often a camera might be a little noisy or you may be shooting with a lot less light than you would really like, so in camera NR might need to be considered.
You need to consider carefully whether you should use in camera NR or not. There will be some cases where you want in camera NR and other times when you don’t.
Post Production NR.
An important consideration is that adding post production NR on top of in-camera NR is never the best route to go down. NR on top of NR will often produce ugly blocky artefacts. If you ever want to add NR in post production it is almost always better not to also add in camera NR. Post production NR has many advantages as you can more precisely control the type and amount you add depending on what the shot needs. When using proper grading software such as DaVinci Resolve you can use power windows or masks to only add NR to the parts of the image that need it.
Before someone else points it out I will add here that it is almost always impossible to turn off all in camera NR. There will almost certainly be some NR added at the sensor that you can not turn off. In addition most recording codecs will apply some noise reduction to avoid wasting data recording the noise, again this can’t be turned off. Generally higher bit rate, less compressed codecs apply less NR. What I am talking about here is the additional NR that can be set to differing levels within the cameras settings that is in addition to the NR that occurs at the sensor or in the codec.
Almost every NR process, as well as reducing the visibility of noise will introduce other image artefacts. Most NR process work by taking an average value for groups of pixels or an average value for the same pixel over a number of frames. This averaging tends to not only reduce the noise but also reduce fine details and textures. Faces and skin tones may appear smoothed and unnatural if excessively noise reduced. Smooth surfaces such as walls or the sky may get broken up into subtle bands or steps. Sometimes these artefacts won’t be seen in the cameras viewfinder or on a small screen and only become apparent on a bigger TV or monitor. Often the banding artefacts seen on walls etc are a result of excessive NR rather than a poor codec etc (although the two are often related as a weak codec may have to add a lot of NR to a noisy shot keep the bit rate down).
If you are shooting log then any minor artefacts in the log footage from in camera noise reduction may be magnified when you start grading and boosting the contrast. So, generally speaking when shooting log it is always best to avoid adding in camera NR. The easiest way to avoid noise when shooting with log is to expose a bit brighter so that in the grade you are never adding gain. Take gain away in post production to compensate for a brighter exposure and you take away much of the noise – without giving up those fine textures and details that make skin tones look great. If shooting log, really the only reason an image will be noisy is because it hasn’t been exposed bright enough. Even scenes that are meant to look dark need to be exposed well. Scenes with large dark areas need good contrast between at least some brighter parts so that the dark areas appear to be very dark compared to the bright highlights. Without any highlights it’s always tempting to bring up the shadows to give some point of reference. Add a highlight such as a light fixture or a lit face or object and there is no need to then bring up the shadows, they can remain dark, contrast is king when it comes to dark and night scenes.
If, however you are shooting for “direct to air” or content that won’t be graded and needs to look as good as possible directly from the camera then a small amount of in camera NR can be beneficial. But you should test the cameras different levels to see how much difference each level makes while also observing what happens to subtle textures and fine details. There is no free lunch here. The more NR you use the more fine details and textures you will lose and generally the difference in the amount of noise that is removed between the mid and high setting is quite small. Personally I tend to avoid using high and stick to low or medium levels. As always good exposure is the best way to avoid noise. Keep your gain and ISO levels low, add light if necessary or use a faster lens, this is much more effective than cranking up the NR.
New Arri-Look LUT
UPDATE – Some issues with the original version of the LUT were found by some users, so I have created a revised version and the revised version is now linked below.
Arri Look LUT’s are clearly very popular with a lot of Sony users, so I have created an Arri-Look LUT for the FX3/FX6/FX9/Venice that can be used to mimic the look from an Arri camera. It is not designed to pretend to be a real Arri camera, but to instead provide an image with the look and feel of an Arri camera but tailored to the Sony sensors.
As usual the LUT is free to download, but if you do find it useful I do ask that you buy me a coffee or other drink as a thank you. All contributions are always most welcome. Additionally do let me know what you like about this LUT or don’t like, so I can look at what LUTs may be good to create in the future.
Click Here to download my Arri-Look LUT (latest version 2C),
And here is a warmer version (may be very slightly too warm), version 2B.
Click below to buy me a thank you drink if you like it and use it.
DaVinci resolve Frame Rendering Issue and XAVC
There is a bug in some versions of DaVinci Resolve 17 that can cause frames in some XAVC files to be rendered in the wrong order. This results in renders where the resulting video appears to stutter or the motion may jump backwards for a frame or two. This has now been fixed in version 17.3.2 so all user of XAVC and DaVinci Resolve are urged to upgrade to at least version 17.3.2.
https://www.blackmagicdesign.com/uk/support/family/davinci-resolve-and-fusion
SDI Failures and what YOU can do to stop it happening to you.
Updated 22/01/2024.
Sadly this is not an uncommon problem. Suddenly and seemingly for no apparent reason the SDI (or HDMI) output on your camera stops working. And this isn’t a new problem either, SDI and HDMI ports have been failing ever since they were first introduced. This issue affects all types of SDI and HDMI ports. But it is more likely with higher speed SDI ports such as 6G or 12G as they operate at higher frequencies and as a result the components used are more easily damaged as it is harder to protect them without degrading the high frequency performance.
Probably the most common cause of an SDI/HDMI port failure is the use of the now near ubiquitous D-Tap cable to power accessories connected to the camera. The D-Tap connector is sadly shockingly crudely designed. Not only is it possible to plug in many of the cheaper ones the wrong way around but with a standard D-Tap plug there is no mechanism to ensure that the negative or “ground” connection of the D-Tap cable makes or breaks before the live connection. There is a however a special but much more expensive D-Tap connector available that includes electronic protection against this very issue (although a great product, even these cannot totally provide protection from a poor ground connection) – see: https://lentequip.com/products/safetap
Imagine for a moment you are using a monitor that’s connected to your cameras SDI or HDMI port. You are powering the monitor via the D-Tap on the cameras battery as you always do and everything is working just fine. Then the battery has to be changed. To change the battery you have to unplug the D-Tap cable and as you pull the D-Tap out, the ground connection disconnects fractionally before the live connection. During that extremely brief moment there is still positive power going to the monitor but because the ground on the D-Tap is now disconnected the only ground route back to the battery becomes via the SDI cable through the camera. For a fraction of a second the SDI/HDMI cable becomes the power cable and that power surge blows the SDI driver chip.
After you have completed the battery swap, you turn everything back on and at first all appears good, but now you can’t get the SDI output to work. There’s no smoke, no burning smells, no obvious damage as it all happened in a tiny fraction of a second. The only symptom is a dead SDI.
And it’s not only D-Tap cables that can cause problems. A lot of the cheap DC barrel connectors have a center positive terminal that can connect before the outer barrel makes a good connection. There are many connectors where the positive can make before the negative.
You can also have problems if the connection between the battery and the camera isn’t perfect. A D-Tap connected directly to the battery might represent an easier route for power to flow back to the battery if there is any corrosion on the battery terminals or a loose batter plate or adapter.
It can also happen when powering the camera and monitor (or other SDI connected devices like a video transmitter) via separate mains adapters. The power outputs of most of the small, modern, generally plastic bodied switch mode type power adapters and chargers are not connected to ground. They have a positive and negative terminal that “floats” above ground at some unknown voltage. Each power supplies negative rail may be at a completely different voltage compared to ground. So again an SDI cable connected between two devices, powered by different power supplies will act as the ground between them and power may briefly flow down the SDI cable as the SDI cables ground brings both power supply negative rails to the same common voltage. Failures this way are less common, but do still occur.
Sadly this is not an uncommon problem. Suddenly and seemingly for no apparent reason the SDI (or HDMI) output on your camera stops working. And this isn’t a new problem either, SDI and HDMI ports have been failing ever since they were first introduced. This issue affects all types of SDI and HDMI ports. But it is more likely with higher speed SDI ports such as 6G or 12G as they operate at higher frequencies and as a result the components used are more easily damaged as it is harder to protect them without degrading the high frequency performance.
Probably the most common cause of an SDI/HDMI port failure is the use of the now near ubiquitous D-Tap cable to power accessories connected to the camera. The D-Tap connector is sadly shockingly crudely designed. Not only is it possible to plug in many of the cheaper ones the wrong way around but with a standard D-Tap plug there is no mechanism to ensure that the negative or “ground” connection of the D-Tap cable makes or breaks before the live connection. There is a however a special but much more expensive D-Tap connector available that includes electronic protection against this very issue (although a great product, even these cannot totally provide protection from a poor ground connection) – see: https://lentequip.com/products/safetap
Imagine for a moment you are using a monitor that’s connected to your cameras SDI or HDMI port. You are powering the monitor via the D-Tap on the cameras battery as you always do and everything is working just fine. Then the battery has to be changed. To change the battery you have to unplug the D-Tap cable and as you pull the D-Tap out, the ground connection disconnects fractionally before the live connection. During that extremely brief moment there is still positive power going to the monitor but because the ground on the D-Tap is now disconnected the only ground route back to the battery becomes via the SDI cable through the camera. For a fraction of a second the SDI/HDMI cable becomes the power cable and that power surge blows the SDI driver chip.
After you have completed the battery swap, you turn everything back on and at first all appears good, but now you can’t get the SDI output to work. There’s no smoke, no burning smells, no obvious damage as it all happened in a tiny fraction of a second. The only symptom is a dead SDI.
And it’s not only D-Tap cables that can cause problems. A lot of the cheap DC barrel connectors have a center positive terminal that can connect before the outer barrel makes a good connection. There are many connectors where the positive can make before the negative.
You can also have problems if the connection between the battery and the camera isn’t perfect. A D-Tap connected directly to the battery might represent an easier route for power to flow back to the battery if there is any corrosion on the battery terminals or a loose batter plate or adapter.
It can also happen when powering the camera and monitor (or other SDI connected devices like a video transmitter) via separate mains adapters. The power outputs of most of the small, modern, generally plastic bodied switch mode type power adapters and chargers are not connected to ground. They have a positive and negative terminal that “floats” above ground at some unknown voltage. Each power supplies negative rail may be at a completely different voltage compared to ground. So again an SDI cable connected between two devices, powered by different power supplies will act as the ground between them and power may briefly flow down the SDI cable as the SDI cables ground brings both power supply negative rails to the same common voltage. Failures this way are less common, but do still occur.
For these reasons you should always connect all your power supplies, power cables, especially D-Tap or other DC power cables first. Avoid using adapters between the battery and the camera as each adapter plate is another possible cause of trouble.
Then while everything remains switched off the very last thing to connect should be the SDI or HDMI cables. Only when everything is connected should you turn anything on.
If unplugging or re-plugging a monitor (or anything else for that matter) turn everything off first. Do not connect or disconnect anything while any of the equipment is on. Although to be honest the greatest risk is at the time you connect or disconnect any power cables such as when swapping a battery where you are using the D-Tap to power any accessories. So if changing batteries, switch EVERYTHING off first, then disconnect your SDI or HDMI cables before disconnecting the D-Tap or other power cables next. Seriously – you need to do this, disconnect the SDI or HDMI before changing the battery if the D-Tap cable has to be unplugged from the battery. Things are a little safer if any D-Tap cables are connected directly to the camera or a power plate that remains connected to the camera. This way you ca change the battery without needing to unplug the D-Tap cables and this does reduce the risk of issues.
Also inspect your cables regularly, check for damage to the pins and the cable, if you suspect it isn’t perfect – throw it away, don’t take the risk.
(NOTE: It’s been brought to my attention that Red recommend that after connecting the power, but before connecting any SDI cables you should turn on any monitors etc. If the monitor comes on OK, this is evidence that the power is correctly connected. There is certainly some merit to this. However this only indicates that there is some power to the monitor, it does not ensure that the ground connection is 100% OK or that the ground voltages at the camera and monitor are the same. By all means power the monitor up to check it has power, then I still recommend that you turn it off again before connecting the SDI).
Then while everything remains switched off the very last thing to connect should be the SDI or HDMI cables. Only when everything is connected should you turn anything on.
If unplugging or re-plugging a monitor (or anything else for that matter) turn everything off first. Do not connect or disconnect anything while any of the equipment is on. Although to be honest the greatest risk is at the time you connect or disconnect any power cables such as when swapping a battery where you are using the D-Tap to power any accessories. So if changing batteries, switch EVERYTHING off first, then disconnect your SDI or HDMI cables before disconnecting the D-Tap or other power cables next. Seriously – you need to do this, disconnect the SDI or HDMI before changing the battery if the D-Tap cable has to be unplugged from the battery. Things are a little safer if any D-Tap cables are connected directly to the camera or a power plate that remains connected to the camera. This way you ca change the battery without needing to unplug the D-Tap cables and this does reduce the risk of issues.
Also inspect your cables regularly, check for damage to the pins and the cable, if you suspect it isn’t perfect – throw it away, don’t take the risk.
(NOTE: It’s been brought to my attention that Red recommend that after connecting the power, but before connecting any SDI cables you should turn on any monitors etc. If the monitor comes on OK, this is evidence that the power is correctly connected. There is certainly some merit to this. However this only indicates that there is some power to the monitor, it does not ensure that the ground connection is 100% OK or that the ground voltages at the camera and monitor are the same. By all means power the monitor up to check it has power, then I still recommend that you turn it off again before connecting the SDI).
The reason Arri talk about shielded power cables is because most shielded power cables use connectors such as Lemo or Hirose where the body of the connector is grounded to the cable shield. This helps ensure that when plugging the power cable in it is the ground connection that is made first and the power connection after. Then when unplugging the power breaks first and ground after. When using properly constructed shielded power cables with Lemo or Hirose connectors it is much less likely that these issues will occur (but not impossible).
Is this an SDI/HDMI fault? No, not really. The fault lies in the choice of power cables that allow the power to make before the ground or the ground to break before the power breaks and a badly designed power connector often made as cheaply as possible. Or the fault is with power supplies that have poor or no ground connection. Additionally you can put it down to user error. I know I’m guilty of rushing to change a battery and pulling a D-Tap connector without first disconnecting the SDI on many occasions, but so far I’ve mostly gotten away with it (I have blown an SDI on one of my Convergent Design Odysseys).
If you are working with an assistant or as part of a larger crew do make sure that everyone on set knows not to plug or unplug power cables or SDI cables without checking that it’s OK to do so – and always unplug the SDI/HDMI before disconnecting or removing anything else.
Is this an SDI/HDMI fault? No, not really. The fault lies in the choice of power cables that allow the power to make before the ground or the ground to break before the power breaks and a badly designed power connector often made as cheaply as possible. Or the fault is with power supplies that have poor or no ground connection. Additionally you can put it down to user error. I know I’m guilty of rushing to change a battery and pulling a D-Tap connector without first disconnecting the SDI on many occasions, but so far I’ve mostly gotten away with it (I have blown an SDI on one of my Convergent Design Odysseys).
If you are working with an assistant or as part of a larger crew do make sure that everyone on set knows not to plug or unplug power cables or SDI cables without checking that it’s OK to do so – and always unplug the SDI/HDMI before disconnecting or removing anything else.
How many of us have set up a camera, powered it up, got a picture in the viewfinder and then plugged an SDI cable between the camera and a monitor that doesn’t have a power connection yet or already on and plugged in to some other power supply? Don’t do it! Plug and unplug in the right order – ALL power cables and power supplies first, check power is going to the camera, check power is going to the monitor, then turn it all off first, finally plug in the SDI.
