So I spent much of last week shooting a short film and commercial (more about the shoot in a separate article). It was shot in raw using my Sony F5, but could have been shot with a wide range of cameras. The “look” for this production is very specific. Much of it set late in the day or in the evening and requiring a gentle romantic look.
In the past much of this look would have been created in camera. Shooting with a soft filter for the romantic look, shifting the white balance with warming cards or a dialled in white balance for a warm golden hour evening look. Perhaps a custom picture profile or scene file to alter the look of the image coming from the camera. These methods are still very valid, but thanks to better recording codecs and lower cost grading and post production tools, these days it’s often easier to create the look in post production.
When you look around on YouTube or Vimeo at most of the showreels and demo reels from people like me they will almost always have been graded. Grading is a huge, modern, part of the finishing process and it makes a huge difference to the final look of a production. So don’t automatically assume everything you see on-line looked like that when it was shot. It probably didn’t and a very, very big part of the look tends to be created in post these days.
One further way to work is to go half way to your finished look in camera and then finish off the look in post. For some productions this is a valid approach, but it comes with some risks and there are some things that once burnt into the recording can be hard to then subsequently change in post, for example any in camera sharpening is difficult to remove in post as are crushed blacks or skewed or offset white balance.
Also understand that there is a big difference between trying to grade using the color correction tools in an edit suite and using a dedicated editing package. For many, many years I used to grade using my editing software, simply because that was what I had. Plug-ins such as Magic Bullet looks are great and offer a quick and effective way to get a range of looks, but while you can do a lot with a typical edit color corrector, it pales into insignificance compared to what can be done with a dedicated grading tool, for example not only creating a look but then adjusting individual elements of the image.
When it comes to grading tools then DaVinci Resolve is probably the one that most people have heard of. Resolve Lite is free, yet still incredibly capable (provided you have a computer that will run it). There are lots of other options too like Adobe Speed Grade, but the key thing is that if you change your workflow to include lots of grading, then you need to change the way you shoot too. If you have never used a proper grading tool then I urge you to learn how to use one. As processing power improves and these tools become more and more powerful they will play an ever greater role in video production.
So how should you shoot for a production that will be graded? I’m sure you will have come across the term “shoot flat” and this is often said to be the way you should shoot when you’re going to grade. Well, yes and no. It depends on the camera you are using, the codec, noise levels and many other factors. If you are the DP, Cinematographer or DiT, then it’s your job to know how footage from your camera will behave in post production so that you can provide the best possible blank canvas for the colourist.
What is shooting flat exactly? Lets say your monitor is a typical LCD monitor. It will be able to show 6 or 7 stops of dynamic range. Black at stop 0 will appear to be black and whites at stop 7 will appear bright white. If your camera has a 7 stop range then the blacks and whites from the camera will be mapped 1:1 with the monitor and the picture will have normal contrast. But what happens when you then have a camera that can capture double that range, say 12 to 14 stops?. The bright whites captured by the camera will be significantly brighter than before. If you then take that image and try to show it on the same LCD monitor you have an issue because the LCD cannot go any brighter than before, so the much brighter whites from the high dynamic range shot are shown at the same brightness as the original low dynamic range shot. Not only that but the now larger tonal range is now squashed together into the monitors limited range. This reduces the contrast in the viewed image and as a result it looks flat.
That’s a real “shoot flat” image (a wide dynamic range shown on a typical dynamic range monitor), but you have to be careful because you can also create a flat looking image by raising the cameras black level or black gamma or reducing the white level. Doing this reduces the contrast in the shadows and mid tones and will make the pictures look low contrast and flat. But raising the black level or black gamma or reducing the white point rarely increases the dynamic range of a camera, most cameras dynamic range is limited by the way they handle highlights and over exposure, not shadows, dark or white level. So just beware, not all flat looking images bring real post production advantages, I’ve seen many examples of special “flat” picture profiles or scene files that don’t actually add anything to the captured image, it’s all about dynamic range, not contrast range. See this article for more in depth info on shooting flat.
If you’re shooting for grading, shooting flat with a camera with a genuinely large dynamic range is often beneficial as you provide the colourist with a broader dynamic range image that he/she/you can then manipulate so that it looks good on typically small dynamic range TV’s and monitors, but excessively raising the black level or black gamma rarely helps the colourist as this just introduces an area that will need to be corrected to restore good contrast rather than adding anything new or useful to the image. You also need to consider that it’s all very well shooting with a camera that can capture a massive dynamic range, but as there is no way to ever show that full range, compromises must be made in the grade so that the picture looks nice. An example of this would be a very bright sky. In order to show the clouds in the sky the rest of the scene may need to be darkened as the sky is always brighter than everything else in the real world. This might mean the mid tones have to be rather dark in order to preserve the sky. The other option would be to blow the sky out in the grade to get a brighter mid range. Either way, we don’t have a way of showing the 14 stop range available from cameras like the F5/F55 with current display technologies, so a compromise has to be made in post and this should be in the back of your mind when shooting scenes with large dynamic ranges. With a low dynamic range camera, you the camera operator would choose whether to let the highlights over expose to preserve the mid range or whether to protect the highlights and put up with a darker mid range. But now with these high dynamic range cameras that decision is largely moved to post production, but you should still be looking at your mid tones and if needed adding a bit of extra illumination so that the mids are not fighting the highlights.
In addition to shooting flat there is a lot of talk about using log gamma curves, S-Log, S-log2, LogC etc. Again IF the camera and recording codec are optimised for Log then this can be an extremely good approach. Remember that if you choose to use a log gamma curve then you will also need to adjust the way you expose to place skin tones etc in the correct part of the log curve. It’s no longer about exposing for what looks good on the monitor or in the viewfinder, but about exposing the appropriate shades in the correct part of the log curve. I’ve written many articles on this so I’m not going to go into it here, other than to say log is not a magic fix for great results and log needs a 10 bit codec if your going to use it properly. See these articles on Log: S-Log and 8 bit or Correct Exposure with Log. Using Log does allow you to capture the cameras full range, it will give you a flat looking image and when used correctly it will give the colourist a large blank canvas to play with. When using log it is vital that you use a proper grading tool that will apply log based corrections to your footage as adding linear corrections in a typical edit application to log footage will not give the best results.
So what if your camera doesn’t have log? What can you do to help improve the way the image looks after post production? First of all get your exposure right. Don’t over expose. Anything that clips can not be recovered in post. Something that’s a little too dark can easily be brightened a bit, but if it’s clipped it’s gone for good. So watch those highlights. Don’t under expose, just expose correctly. If you’re having a problem with a bright sky don’t be tempted to add a strong graduated filter to the camera to darken the sky. If the colorist tries to adjust the contrast of the image the grad may become more extreme and objectionable. It’s better to use a reflector or some lights to raise the foreground rather than a graduated filter to lower the highlight.
One thing that can cause grading problems is any knee compression. Most video cameras by default use something called the “Knee” to compress highlights. This does give the camera the ability to capture a greater dynamic range, but this is done by aggressively compressing together the highlights and it’s either on or off. If the light changes during the shot and the cameras knee is set to auto (as most are by default) then the highlight compression will change mid shot and this can be a nightmare to grade. So instead of using the cameras default knee settings use a scene file or picture profile to set the knee to manual or use an extended range gamma curve like a Hypergamma or Cinegamma that does not have a knee and instead uses a progressive type of highlight compression.
Another thing that can become an issue in the grading suite is image sharpening. In camera sharpening such as detail correction works by boosting contrast around edges. So if you take an already sharpened image into the grading suite and then boost the contrast in post, the sharpening will become more visible and the pictures may take on more of a video look or become over sharpened. It’s just about impossible to remove image sharpening in post, but to add a bit of sharpening is quite easy. So, if you’re shooting for post consider either turning off the detail correction circuits all together or at the very least reduce the levels applied by a decent amount.
Color and white balance: One thing that helps keep things simple in the grade is having a consistent image. The last thing you want is the white balance changing half way through the shot, so as a minimum use a fixed white balance or preset white balance. I find it better to shoot with preset white when shooting for a post heavy workflow as even if the light changes a little from scene to scene or shot to shot the RGB gain levels remain the same so any corrections applied have a similar effect, the colourist then just tweaks the shots for any white balance differences. It’s also normally easier to swing the white balance in post if preset is used as there won’t be any odd shifts added as can sometimes happen if you have used a grey/white card to white balance.
Just as the brightness or luma of an image can clip if over exposed then so too can the colour. If you’re shooting colourful scenes, especially shows or events with coloured lights then it will help you if you reduce the saturation of the colour matrix by around 20%, this allows you to record stronger colours before they clip. Colour can then be added back in in the grade if needed.
Noise and grain: This is very important. The one thing above all the others that will limit how far you can push your image in post is noise and grain. There are two sources of this, camera noise and compression noise. Camera noise is dependant on the cameras gain and chosen gamma curve. Aways strive to use as little gain as possible, remember that if the image is just a little dark you can always add gain in post, so don’t go adding un-necessary gain in camera. A proper grading suite will have powerful noise reduction tools and these normally work best if the original footage is noise free and then gain added in post, rather than trying to de-noise grainy camera clips.
The other source of noise and grain is compression noise. Generally speaking, the more highly compressed the video stream is then the greater the noise will be. Compression noise is often more problematic than camera noise as in many cases it will have a regular pattern or structure which makes it visually more distracting than random camera noise. More often than not the banding seen in images across the sky or flat surfaces is caused by compression artefacts rather than anything else and during grading any artefacts such as these can become more visible. So try to use as little compression as possible, this may mean using an external recorder but these can be purchased or hired quite cheaply these days. As always, before a big production test your workflow. Shoot some sample footage, grade it and see what it looks like. If you have a banding problem, suspect the codec or compression ratio first, not whether it’s 8 bit or 10 bit, in practice it’s not 8 bit that causes banding, but too much or poor quality compression (so even a camera with only an 8 bit output like the FS700 will benefit from recording on a better quality external recorder).
RAW: Of course the best way of providing the colourist (even if that’s yourself) the best blank canvas is to shoot with a camera that can record the raw sensor data. By shooting raw you do not add any in camera sharpening or gamma curves that may then need to be removed in post. In addition raw normally means capturing the cameras full dynamic range. But that’s not possible for everyone and generally involves working with very large amounts of data. If you follow my guidelines above you should at least have material that will allow you a good range of adjustment and fine tuning in post. This isn’t “fix it in post”, we are not putting right something that is wrong. We are shooting in a way that allows us to make use of the incredible processing power available in a modern computer to produce great looking images. You are making those last adjustments that make a picture look great using a nice big monitor (hopefully calibrated) in a normally more relaxed environment than on most shoots.
The way videos are produced is changing. Heavy duty grading used to be reserved for high end productions, drama and movies. But now it is common place, faster and easier than ever. Of course there are still many applications where there isn’t the time for grading, such as TV news, but grading is going to play an every greater part in more and more productions, so it’s worth learning how to do it properly and how to adjust your shooting setup and style to maximise the quality of the finished production.
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