Tag Archives: cinematography

Notes on Timecode and Timecode Sync for cinematographers.

This is part 1 of two articles. In this article I will look at what timecode is and some common causes of timecode drift problems. In part 2 I will look at the correct way to synchronise timecode across multiple devices.

This is a subject that keeps cropping up from time to time. A lot of us camera operators don’t always understand the intricacies of timecode. If you live in a PAL/50Hz area and shoot at 25fps all the time you will have few problems. But start shooting at 24fps, 23.98 fps or start trying to sync different cameras or audio recorders and it can all get very complicated and very confusing very quickly.

So I’ve written these notes to try to help you out.

WHAT IS TIMECODE?

The timecode we normally encounter in the film and video world is simply a way to give every frame that we record a unique ID number based on the total number of frames recorded or the time of day.  It is a counter that counts whole frames. It can only count whole frames, it cannot count fractions of frames, as a result the highest accuracy is 1 frame. The timecode is normally displayed as Hour:Minute:Second:Frame in the following format

HH:MM:SS:FF

RECORD RUN AND FREE RUN

The two most common types of timecode used are “Record Run” and “Free Run”. Record run, as the name suggests only runs or counts up when the camera is recording. It is a cumulative frame count, which counts the total number of frames recorded. So if the first clip you record starts with the time code clock at 00:00:00:00 and runs for 10 seconds and 5 frames then the TC at the end of the clip will be 00:00:10:05. The first frame of the next clip you record will continue the count so will be 00:00:10:06 and so on. When you are not recording the timecode stops counting and does not increase.

With “Free Run” the timecode clock in the camera is always counting according to the frame rate the camera is set to. It is common to set the free run clock so that it matches the time of the day. Once you set the time in the timecode clock and enable “Free Run” the clock will start counting up whether you are recording or not.

HERE COMES A REALLY IMPORTANT BIT!

In “Free Run” once you have set the timecode clock it will always count the number of frames recorded and in some cases this will actually cause the clock to drift away from the actual time of day.

SOME OF THE PROBLEMS.

An old problem is that in the USA and other NTSC areas the frame rate is a really odd frame rate, it’s 29.97fps (this came about to prevent problems with the color signal when color TV was introduced). Timecode can only count actual whole frames, so there is no way to account for the missing 0.03 frames in every second. As a result timecode running at 29.97fps runs slightly slower than a real time clock.

If the frame rate was actually 30fps in 1 hour there would be 108,000 frames. But at 29.97fps after one real time hour you will have only recorded  107,892 frames, the frame counter TC, won’t reach one hour for another 3.6 seconds.

DROP FRAME TIMECODE.

To eliminate this 3.6 seconds per hour (relative to real time) timecode discrepancy in footage filmed at 29.97fps a special type of time code was developed called “Drop Frame Timecode“. Drop Frame Timecode (DF) works by: every minute, except each tenth minute, two timecode numbers are dropped from the timecode count. So there are some missing numbers in the timecode count but after exactly 1 real time hour the time code value will increment by 1 hour. No frames themselves are dropped, only numbers in the frame count.

WHEN TO USE DROP FRAME (DF) OR NON DROP FRAME (NDF).

Drop Frame Timecode is only ever used for material shot at  29.97fps, which includes 59.94i. (We will often incorrectly refer to this as 60i or 30fps – virtually all 30fps video these days is actually 29.97fps). If you are using “Rec Run” timecode you will almost never need to use Drop Frame as generally you will not by syncing with anything else.

If you are using 29.97fps  “Free Run” you should use Drop Frame (DF) when you want your timecode to stay in sync with a real time clock. An example would be shooting a long event or over several days where you want the timecode clock to match the time on your watch or the watch of an assistant that might be logging what you are shooting.

If you use 29.97fps Non Drop Frame  (NDF) your cameras timecode will drift relative to the actual time of day by a minute and a half each day. If you are timecode syncing multiple cameras or devices it is vital that they are all using the same type of timecode, mixing DF and NDF will cause all kinds of problems.

It’s worth noting that many lower cost portable audio recorders that record a “timecode” don’t actually record true timecode. Instead they record a timestamp based on a real time clock. So if you record on the portable recorder for lets say 2 hours and then try to sync the 1 hour point (01:00:00:00 Clock Time) with a camera recording 29.97fps NDF timecode using the 1 hour timecode number (01:00:00:00 NDF Timecode) they will be out of sync by 3.6 seconds. So this would be a situation where it would be preferable to use DF timecode in the camera as the cameras timecode will match the real time clock of the external recorder.

WHAT ABOUT 23.98fps?

Now you are entering a whole world of timecode pain!!

23.98fps is a bit of a oddball standard that came about from fitting 24fps films into the NTSC 29.97fps frame rate. It doesn’t have anything to do with pull up, it’s just that as NTSC TV runs at 29.97fps rather than true 30fps movies are sped up by 0.1% to fit in 29.97fps.

Now 23.98fps exists as a standalone format. In theory there is still a requirement for Drop Frame timecode as you can’t have 0.02 frames in a timecode frame count, each frame must have a whole number. Then after a given number of frames you go to the next second in the count. With 23.98fps we count 24 whole frames and the increment the timecode count by one second, so once again there is a discrepancy between real time and the timecode count of 3.6 seconds per hour. The time on a camera running at 23.98fps will run fast compared to a real time clock.  Unlike 29.97fps there is no Drop Frame (DF) standard for 23.98, it’s always treated as a 24fps count (TC counts 24 frames, then adds 1 to the second count), this is because there  is no nice way to adjust the count and make it fit real time as there is with 29.97fps. No matter how you do the math or how many frames you drop there would always be a fraction of a frame left over.

So 23.98fps does not have a DF mode. This means that after 1 hour of real time the timecode count on a camera shooting at 23.98 fps will be 00:01:03:14. If you set the camera to “Free Run” the timecode will inevitably drift relative to real time, again over the course of a day the camera will be fast by almost one and a half minutes compared to a real time clock or any other device using either drop frame timecode, 24fps or 25fps.

So, as I said earlier 23.98fps timecode can be painful to deal with.

24fps timecode does not have this problem as there are exactly 24 frames in every second, so a video camera shooting at 24fps should not see any significant timecode drift or loss of timecode sync compared to a real time clock.

It’s worth considering here the problem of shooting sync sound (where sound is recorded externally on a remote sound recorder). If your sound recorder does not have 23.98fps timecode the timecode  will drift relative to a camera shooting at 23.98fps. If your sound recorder only has a real time timecode clock you might need to consider shooting at 24fps instead of 23.98fps to help keep the audio and picture time codes in sync. Many older audio recorders designed for use alongside film cameras can only do 24fps timecode.

In part 2 I will look at the correct way to synchronise timecode across multiple devices.

CLICK HERE FOR PART 2

 

Why Do We Need To Light?

Lets face it cameras are becoming more and more sensitive. We no longer need the kinds of light levels that we once used to need. So why is lighting still so incredibly important. Why do we light?

Starting at a most basic level, there are two reason for lighting a scene. The first and perhaps most obvious is to add enough light for the camera to be able to “see” the scene, to get an adequate exposure. The other reason we need to light, the creative reason why we need to light is to create shadows.

It is not the light in a scene that makes it look interesting, it is the shadows. It is the contrast between light and dark that makes an image intriguing to our eyes and brain. Shadows add depth, they can be used to add a sense of mystery or draw the viewers gaze to the brighter parts of the scene. Without shadows, without contrast most scenes will be visually uninteresting.

Take a typical daytime TV show. Perhaps a game show. Look at how it has been lit. In almost every case it will have been lit to provide a uniform and even light level across the entire set. It will be bright so that the cameras can use a reasonable aperture for a deep depth of field. This helps the camera operators keep everything focus. The flat, uniform light means that the stars or contestants can go anywhere in the set and still look OK. This is lighting for exposure, where the prime driver is a well exposed image.  The majority of the light will be coming from the camera side of the set or from above the set with all the light flooding inwards into the set.

eggheadsteam-e1479407949570 Why Do We Need To Light?
Typical TV lighting, flat, very few shadows, light coming from the camera side of the set or above the set.

Then look at a well made movie. The lighting will be very different. Often the main source of light will be coming from the side or possibly even the rear of the scene. This creates dark shadows on the opposite side of the set/scene. It will cast deep shadows across faces and it’s often the shadow side of a face that is more interesting than the bright side.

blade-runner1 Why Do We Need To Light?
Striking example of light coming from opposite the camera to create deep shadows – Bladerunner.

A lot of movie lighting is done from diagonally opposite the cameras to create very deep shadows on faces and to keep the background of the shot dark. If, as is typical in TV production your lights are placed where the cameras are and pointed into the set, then all the light will go into set and illuminate the set from front to back. If your lights are towards the side or rear of the set and are facing towards the cameras the light will be falling out of and away from the set rather than into the set. This means you can then keep the rear of the set dark much more easily. Having the main light source opposite the camera is also why you see far more lens flare effects in movies compared to TV as the light is often shining into the camera lens.

960_1 Why Do We Need To Light?
Another example of the main light sources coming towards the camera. The assassination of Jesse James by the coward Robert Ford.

If you are shooting a night scene and you want to get nice clean pictures from your camera then contrast becomes key. When we think of what things look like at night we automatically think “dark”. But cameras don’t like darkness, they like light, even the modern super sensitive cameras still work better when there is a a decent amount of light. So one of the keys to a great looking night scene is to light the foreground faces of your cast well but keep the background very dark. You expose the camera for the bright foreground (which means you should not have any noise problems) and then rely on the fact that the background is dark to make the scene look like a night scene.  Again the reason to light is for better shadows, to make the darker parts of the scene appear very dark relative to the foreground and a high level of contrast will make it look like night. Consider a bright moonlit night, faces will be bright compared to everything else.

sam-shepard-jesse-james-e1479407719922 Why Do We Need To Light?
A well lit face against a very dark background means low noise night shot. Another example from The assassination of Jesse James by the coward Robert Ford.

So in cinematography, very often the reason to add light is to create shadows and contrast rather than to simply raise the overall light level. To make this easier we need to think about reflections and how the light that we are adding will bounce around the set and reduce the high contrast that we may be seeking. For this reason most film studios have black walls and floors. It’s amazing how much light bounces of the floor. Black drapes can be hung against walls or placed on the floor as “negative fill” to suck up any stray light. Black flags can be used to cut and control any undesired light output from your lamps and a black drape or flag placed on the shadow side of a face will often help increase the contrast across that face by reducing stray reflections. Flags are as important as lights if you want to control contrast. Barn doors on a lamp help, but if you really want to precisely cut a beam of light the flag will need to be closer to the subject.

I think most people that are new to lighting focus too much on the lights themselves and don’t spend enough time learning how to modify light with diffusers, reflectors and flags. Good video lights are expensive, but if you can’t control and modify that light you may as well just by a DIY floodlight from your local hardware store.

Also consider using fewer lights. More is not necessarily better. The more lights you add the more light sources you need to control and flag. The more light you will have bouncing around your set reducing your contrast and spilling into your otherwise nice shadows. More lights means multiple shadows going in different directions that you will have to deal with.  Instead of using lots of lights be more careful about where you place the lights you do have, make better use of diffusion perhaps by bringing it closer to your subject to get more light wrap around rather than using separate key and fill lights.

 

Creative Composition and Digital Cinematography Workshops – Singapore.

965437_547020298723068_486905373_o-300x168 Creative Composition and Digital Cinematography Workshops - Singapore.
Alister Chapman providing a workshop.

I’m running some workshops for Singapore Media Academy in September. Spaces are limited and I don’t get to visit Asia as much as I used to. So if you are interested in attending one of my highly regarded and popular workshops here is a great opportunity.

CREATIVE COMPOSITION:
The first is on Creative Composition. Good shot composition can make or break a production. In the workshop I will guide you through ways to achieve images that will draw the audience in, focus the viewers attention or create different emotional reactions.  I will show you how to deal with composition in moving shots, something that can be difficult. We will use case studies of well known movies to see clever use of classic techniques such as the rule of thirds, vanishing lines or Fibonacci curves. We will see how subtle lighting changes can be used to direct the audiences gaze. From the framing of a simple interview to the staging of a complex scene the workshop will help you develop engaging and interesting images. Understanding basic composition is one of the keys to great productions whether it’s for TV news or the cinema.
DIGITAL CINEMATOGRAPHY, LOG AND RAW (Plus HDR).
The second workshop is on Digital Cinematography, Log and Raw. This is an essential workshop for those serious about obtaining the best possible images with a modern electronic video camera. I will explain the differences between standard gammas, log and raw in a way that’s easy to understand but will give you all the information you need to be able to make informed decisions about which to use and when. Next I will teach you how to expose Log and Raw looking closely at how to use exposure offsets for the best results in differing lighting conditions. Then we will look at Look Up Tables. I’ll show you how and when to use them and how to easily create your own. We will finish with some practical end to end workflow sessions where you will develop your own LUT’s, shoot with log or raw and then perform a basic grade on your content. This will include how to use color managed grading tools such as the Academy of Motion Pictures workflow “ACES”. There’s no hard to understand mathematics, no complex formula’s, just easy to understand explanations and great practical tips and advice that will make log and raw easy to understand and use. I will also include how to expose and shoot for HDR and what you need to consider for HDR productions. More details can be found with the links below:
 
 

How much technology does a modern cinematographer need to know?

This post might be a little controversial, I am often told “you don’t need to know the technical stuff to be a cinematographer” or “I don’t need to know about log and gamma, I just want to shoot”.

I would argue that unless you are working closely with a good DIT a modern DP/Cinematographer really does need to understand many of the technical aspects of the equipment being used, in particular the settings that alter the way the camera captures the images. Not just things like “set it to gamma x for bright scenes” but why you would want to do that.

Now I’m not saying that you have to be a full blown electronics engineer, but if you really want to capture the best possible images it really is very important that you truly understand what the camera is doing. It’s also a huge help to understand how your footage will behave in post production. Any craftsman should understand the correct way to use his tools and not only know how to use them but how they work.

Part of the understanding of how your chosen camera behaves comes from testing and experimentation. Shooting test clips across a range of exposures, trying different gamma or log curves and then taking the footage into post production and seeing how it behaves.

Film cinematographers will shoot tests with different film stocks before a large production under the kinds of lighting conditions that will be encountered during the film. Then the film would be processed in different ways to find the best match to the look the cinematographer is trying to achieve. Digital cinematographers should be doing the same and importantly understanding what the end results are telling them.

Most of the great painters didn’t just pick up a paint brush and slap paint on a canvas. Many artists from  Da Vinci to Turner studied chemistry so they could develop new paints and painting techniques. DaVinci was a pioneer of oil painting, Turner used to make his own paints from base pigments and chemicals and patented some of the unique colors he created.

This doesn’t take anything away from the traditional skills of lighting and composition etc, those are just as important as ever and always will be. But modern electronic cameras are sophisticated devices that need to be used correctly to get the best out of them.  I believe that you need to understand the way your camera responds to light. Understands it’s limitations, understand it’s strengths and learn how to use those strengths and avoid the weaknesses.

And that’s a really important consideration. Today the majority of the cameras on the market are capable of making great images…… Provided you know how to get the best from them. One may be stronger in low light, one may be better in bright light. It may be that one camera will suit one job or one scene better than another. You need to learn about these differences and understanding the underlying technologies will help you figure out which cameras may be candidates for your next project.

It’s not just the camera tech that’s important to understand but also how to manage the footage all the way from the camera to delivery. While you don’t need to be an expert colorist, it certainly helps if you know the process, just as film cameramen know about color timing and film processing. A trend that is growing in the US is high end cinematographers that also grade.

This has come about because in the days of film the cinematographer could determine the look of the finished production through a combination of lighting, the choice of film stock and how it was to be processed. Today a cinematographer may have much less control  over the final image as it passes through the post production and grading process. Often the final look is determined by the colorist as much as the cinematographer. By also becoming colorists and staying with their material all the way through post production, cinematographers can retain control of the final look of the production.

As HDR (High Dynamic Range) delivery becomes more important along with the need to deliver SDR content at the same time, a good understanding of the differences between and limitations of both systems will be needed as you may need to alter the way you expose to suit one or the other.

So, there is lots that you need to know about the technology used in todays world of digital cinematography. Where there is a big enough budget DIT’s (Digital Imaging Technicians) can help cinematographers with guidance on camera setups, gamma, color science, LUT’s and workflows. But at the low budget end of the market, as a cinematographer you need at the very least a firm grasp of how a modern camera works, how to correctly mange the dat it produces (you would be amazed how many people get this wrong). Finally how the material handles in post production, if you really want to get the best from it.

It isn’t simple, it isn’t always easy, it takes time and effort. But it’s incredibly rewarding when it all comes together and results in beautiful images.

If you disagree or have your own take on this please post a comment. I’d love to hear other views.