In the past we’ve focused on teaching you about underwater still photography, including (amongst other topics) equipment, locations and techniques. In the next few issues, we’re going to be diversifying a little, with a series of articles about underwater video.
As with any topic, there are various degrees of understanding to underwater video. For now, we’re going to be concentrating on helping you get to grips with the basics, and we’ll be breaking it down into small digestible topics, which will include:
- Equipment (camera’s and housings, planning a trip or shoot)
- Lighting and Colour (underwater lights, white balancing, using filters)
- Technique (diving for underwater video, camera movements)
- Post processing (capturing, editing, colour correction, sharing)
In this first article, we’re going to look at some general video theory, including:
- Why shoot video?
- Frame rates
- Progressive or interlaced?
- Aspect ratios
Why Shoot Video?
People have different reasons for first taking a video camera underwater. Some divers turn to video in an effort to generally rejuvenate their interests in diving. Once you have a camera in your hands, the quietest of dive sites can become a haven, you can spend an entire dive waiting to capture a certain fish species, or rare behaviour.
For others, it can be out of necessity. Many resort or live-aboard dive guides shoot holiday videos for guests to supplement income. Commercial divers regularly use video camera cameras for inspection work, to show a client a progress or damage to an underwater construction.
There’s also the obvious application of professional filming work for documentaries and feature films. A select few individuals specialize in high definition and large format film work, creating ‘blue-chip’ documentaries for broadcast and theatre release. The majority of divers however simply shoot for fun, and to share their underwater experiences. Thanks to technological advances, it’s now easier than ever to successfully shoot, edit and share your videos.
Cameras are simultaneously getting cheaper and better, and the technology surrounding underwater housings and lighting systems is also helping us to achieve consistently better results. Many computers now come with video editing software such as iMovie, which allow you to easily put together basic movies. You can also buy consumer version’s of professional software packages such as Final Cut Pro, these provide an end to end software solution, allowing you to capture footage from your video tape, edit and output to a variety of different formats.
Sharing your videos is now also easier than ever. With the advent of websites such as youtube, you can share your videos with friends and family, or create podcasts for people to subscribe to and regularly download. After taking all this into account, there really seems that there’s never been a better time to get into underwater video.
There’s a number different video formats available these days. We only really need to look at a couple, DV and HDV. Other formats generally remain solely the territory of professional cinematographers, and are not suitable for recreational divers for a number of reasons, including the costs involved, as well as the logistical issues relating to transportation of large numbers of support equipment that professional systems demand.
DV has been a popular format for a long time now, and is still very popular today. The cameras are still available to buy, as are the housings and other support equipment, but the advent of a newer, better format has taken DV’s place as the most common video format in use.
Roughly three years ago, Sony released their first HDV camera. Since this time, the HDV format—which was created by a consortium of manufacturers including Sony, Canon, Sharp and JVC—has gained tremendous popularity. Many production companies and networks have adopted the format for a variety of uses. Often times, to save costs, a production may consist of a mixture of true
High Def material alongside HDV material, the picture quality is that good. Even though its been adopted by major industry players, don’t think that HDV is for professionals only. Many different manufacturers produce HDV cameras, and there are models available for as little as $1000, which produce stunning results. More and more cameras become available, some of which even have switchable frame rates, or can be switched between progressive or interlaced modes. Both DV and HDV use the same storage medium—mini-DV videocassette tapes.
FPS, Frames per Second
The number of images that a video camera records in a second is known as the ‘frame rate’. In order to trick the eye into seeing movement rather than a series of still images, a minimum number of frames per second must be seen. Old mechanical cameras used to shoot frame rates as slow as six or eight fps, but modern, professional level cameras can shoot as much as 120fps, which can be used to show fast action in slow motion.
Different geographical regions use different frame rates, for example Europe, Asia and Australasia use 25fps, which is known as PAL. USA, Canada and Japan, etc., use NTSC or 29.97fps. Generally, you’ll only ever shoot the frame rate that is used in your country of residence.
Progressive or Interlaced?
Video cameras can record in either interlaced or progressive formats. Interlacing was created as a means to provide visual quality inside the limitations of narrow bandwidth for broadcast. When material is interlaced, every frame is divided into odd and even horizontal lines, and the two are scanned separately.
Progressive, as it sounds, progressively scans each individual frame, in the same way that a film camera does. Many professional level video cameras can be set to record either progressive or interlaced.
Oftentimes, people choose to shoot progressive as it gives a more filmic, cinematic look, as well as ensuring the maximum compatibility with old film stock. The ability to switch cameras inbetween interlaced and progressive formats is now filtering down into smaller, consumer level cameras.
Video format abbreviations often include an ‘i’ or ‘p’ to indicate interlaced or progressive recording: 50i, 60i, 24p etc.
For some applications, including underwater and wildlife video work, interlaced formats can be more popular. Fast moving subjects, like the subjects we often encounter underwater are preserved better when using an interlaced format, but ultimately what you shoot is down to personal preference.
It’s important to look into the various frame rates and formats before you make decisions on purchasing equipment, make sure that the camera you’re looking at shoot’s the right format for the kind of work you plan to do.
The term aspect ratio is used to describe the width and height of your video picture. The most common aspect ratios are 16 x 9 and 4 x 3.
Traditional television screens are 4 x 3, but new high definition and ‘widescreen’ displays are 16 x 9. This is the same aspect as traditional 35mm film, and so has a more cinematic look and feel.
16 x 9, as a general rule is a more popular aspect ratio these days, one reason being that the human eye view’s a widescreen image more comfortably than a traditional 4 x 3 one. On a personal note, I find working in the 16 x 9 aspect ratio much more enjoyable.
It’s worth bearing in mind the final use of whatever footage you’re shooting. If you want to view it on your home TV system, then you’ll may be best going for 16 x 9, but if you exclusively want to view it on a personal device, such as an iPad, the screen would be 4 x 3, if you shoot 16 x 9 then you’d either need to ‘letterbox’ your final movie, or adjust it in some other way when you edit it.
Hopefully now some of the jargon behind video cameras is a little clearer. In the next issue we’ll be looking closely at what cameras are available on the market today, what their advantages and disadvantages are. We’ll also look at some different types of housings, and what other equipment considerations you should undertake before you decide to get wet! ■