About DSLR cameras with video mode
In 2008 Nikon introduced the D90, the world’s first DSLR camera capable of capturing High Definition video (HD). But why hadn’t it been done before? Inside a DSLR there is a mirror which has to flip out of the way to expose an image, but as video demands a high number of frames per second this isn’t mechanically possible.
Compact digital cameras, without an optical viewfinder, have no mirror – meaning capturing video has been possible for some time. However, until more recently they have been low resolution and of a low frame rate, usually 15fps. Movies, at least theoretically, need to be captured upward of 24fps to produce movement smooth to the eye.
To capture video, DSLRs take advantage of live view mode where the mirror locks up and a continuous live feed is displayed on the LCD. Simultaneously this data can then be captured.
An advantage of using a DSLR for video capture is that you can use your existing lenses, from wideangle through to telephoto. This gives greater creative flexibility, plus – due to larger sensor sizes found in DSLRs matching that of professional 35mm video cameras – the potential for a ‘Hollywood-style’ shallow depth of field. Off-the-shelf video cameras tend to have small sensors which limits the depth of field.
So what’s the catch and what are the limitations of using a stills camera to shoot video?
The concept of one ‘do it all’ camera sounds great – just imagine swapping between stills and HD video capture at the flick of a switch. Well, now you can, with the Nikon D90, Canon EOS 5D Mk II, Pentax K7 and Panasonic Lumix GH1. Nikon and Canon also have entry-level versions in the form of the Nikon D5000 and Canon EOS 500D.
However, there are limitations to recording time. At full resolution, Nikon currently tops out at five minutes, Canon at 12 and Panasonic at 29. This is partly due to tax rates – a stills camera that can record more than 30 minutes of footage would, for tax purposes, be deemed a video camera. Other reasons include sensor overheating and buffer limitations as to how much data can be processed in any one sitting.
However, you can record sequences directly one after the other with a break in continuity. Although this may seem a hindrance, in reality it’s rare to shoot a sequence for longer than a couple of minutes – look at any program on telly and you’ll see most shots are held for a few seconds.
Your Essential Guide to DSLR Video – Understanding Digital Video
In order to get the best possible video, we have to change our shooting techniques. One of the problems with using a DSLR is that the camera itself – while in live view mode – is not ideally suited for capturing video. In order to see what you are capturing you have to hold the camera away from your body to view the LCD screen, which can introduce camera shake. A good tripod will cure this problem, but this takes away some of the spontaneity that is enjoyed when shooting handheld. But, as stills photographers we tend to look at pictures in either the Landscape or Portrait orientation too, whereas video has to be shot landscape, unless you want your audience to watch your footage sideways.
Panning too fast across a static scene can make the image look blurry, while a slower pan using a tripod will produce better results. The CMOS sensor, as used by Nikon and Canon, builds up the picture from top to bottom. This can cause distortion when panning as the bottom section of the sensor receives light after the top part, possibly causing some skew in upright lines. Say you were using the camera in video mode during a wedding or other function and someone else’s flash fires – you may end up with a frame that has the flash captured on the upper half only, for example. A CCD sensor does not suffer from these problems.
Focusing can also throw a spanner in the works. DSLR video modes may turn off autofocus – indeed many cannot utilise it – and base the recording on the focus and exposure as determined using live view prior to shooting. Also, where manual focus is used, it can be tricky to hold the camera steady when turning the focusing ring. Not ideal for tracking a subject when capturing a fast-moving action scene, perhaps. Some more-advanced cameras do have autofocus available, though only one, the Panasonic GH1, has developed new lenses that are silent enough not to be picked up by the inbuilt microphone when finding focus.
Movies can be captured in a variety of sizes, the smallest standard being 320 x 240 (VGA), and 640 x 480. These sizes are enough for web use, but for high-quality work, or DVDs, they do not offer sufficient quality.
Standard Definition (SD) video cameras capture footage at 576 x 720 – the same resolution as a UK DVD – and these can have an aspect ratio of 4:3 or 16:9 (anamorphic widescreen).
High definition video starts at 1280 x 720 (HD), moving up to 1440 x 1080 (HDV) and 1920 x 1080 (Full HD). The first figure in each case is the number of pixels across, the second figure is the number of lines down, i.e. 1280 pixels x 720 lines is HD 720.
HDV captures 1440 square pixels but converts them to non-square rectangular pixels in order to display full 1920. This process does mean a small loss in image quality.
Given that video uses a fixed pixel size, in theory there should be no noticeable quality difference between a compact camera shooting Full HD to an advanced DSLR such as the Canon 5D Mk II. However, DSLR cameras have a larger sensor size which means the sampled pixels can be further apart, thereby reducing image noise. DSLR cameras generally also have superior optics for sharper focus and more advanced features to make video stand out.
Video Image Sizes
- SD = 720 x 576
- HD = 1280 X 720
- HDV = 1440 x 1080
- Full HD = 1920 x 1080
View, Share Burn – Making the most of your videos
Use your HD TV
As more of us invest in HD TVs, it’s possible to squeeze that extra bit of use out of them. Many cameras now come with HDMI ports, meaning – with the use of an HDMI cable – it’s possible to directly show both your photos and videos straight from camera in large, glorious high definition on your HD TV. As many companies produce a wide range of electronics, there’s greater compatibility too. Take Panasonic’s VIERA HD TV range; connect the Lumix GH1 via HDMI and you can use the TV’s remote control to browse and play back.
Share on the internet and YouTube
YouTube is so popular that even the cheery Prime Minister has used it as a tool to address the nation. Well, you can use it to share your videos too, and it’s free. Creating a profile is quick and easy, and you can quickly share your videos for the world to see – or just your friends. Some cameras come with specific modes to streamline uploading your videos, though it’s not rocket science to learn the process yourself and the site will help you step by step. Other products such as Google Video, Yahoo! Video, and many others offer a similar video sharing service too.
Still cameras have an option to shoot in JPEG, TIFF or Raw. Video cameras usually offer just one native format. This could be WMV, (Windows Media Video), AVI (Audio Video Interleave), MOV (QuickTime movie), or AVCHD (an HD format that’s becoming increasingly popular). Here is a quick roundup of some of the main video formats and what they mean:
- AVI – Audio Video Interleave
- MOV – QuickTime movie
- AVCHD – Advanced Video Codec High Definition
- WMV – Windows Media Video
- SWF/FLV – Shockwave Flash / Flash Video
- MP4/MPEG4 – Moving Picture (Experts Group, v4)
- RM – Real Media
- H.264 – Advanced Video Codec for MPEG4 files (MPEG4 Part 10)
- DiVX/DMF – DivX format
We are all used to capturing stills using the JPEG format, and for video there is MPEG format. HD movies can occupy several gigabytes for a short sequence, so in order to fit it all on a memory card the movie has to use compression. MPEG2 and MPEG4/H.264 are the popular choice. This uses a LGOP algorithm, LGOP standing for Long Group of Pictures. Compressing a still image is relatively easy: just analyse the single picture and compress it. With movies it is slightly more complicated. Movies are made up from sequences of still pictures. In the UK we use 25 frames per second (fps) on our TV sets; in North America they use 30fps (29.97 to be technically accurate). These frames are divided up into Groups of Pictures, generally 12 for a LGOP. The first frame is sampled and then the next 11 frames are made up from the first reference frame, then the process repeats with a new key frame. For most practical purposes this works fine, until you start to pan to capture some fast action, where you may end up with a ‘smeared’ looking sequence. Ideally, a shorter grouping of pictures would be a better solution, though this would result in much larger files. A four-minute sequence captured in Full HD (1920 x 1080) using MPEG2 compression wilL occupy 1 gigabyte (1048MB); the same four- minute sequence without compression occupies 32,457 gigabytes.
In general, DSLRs regard audio as an added feature with very little importance. This is a little short-sighted as audio is an essential part of any production. Nikon and Canon both use a small mono microphone on the camera body, which annoyingly also picks up any handling noises. The Panasonic GH1 has a stereo microphone on the camera’s prism and a mini plug for an external microphone. The Canon 5D Mk II and the new Pentax K7 also have sockets for an external mic – best for professional recording.
Video is captured in frames per second (fps), and generally the two popular frame rates are 25fps and 30fps. Both are recognised as TV standard. In Europe and the UK we use the 50Hz PAL TV standard (Phase Alternating Line), which refreshes at a rate of 50 interlaced fields per second (i.e. 25 full frames per second). In North America they use the 60Hz NTSC standard (National Television System Committee) which plays at 29.97 interlaced frames per second. Capturing video at 30fps may not appear to play as smoothly as 25fps on a PAL system due to the refresh rate.
Progressive or Interlaced
You may see that video is captured in either 25p or 50i. The 25p denotes that frames are captured in Progressive mode, meaning that the entire image is captured in a single frame. 50i, Interlaced, means that each frame is actually made up from two adjacent frames. The first frame captures the odd lines and the second frame captures the even lines. The two frames are then seemingly combined one after the other to produce an interlaced frame. Interlaced video produces smoother movement in action but can also cause a tearing effect in faster movement. Progressive or Interlaced has no bearing on resolution, only the frame rate.
Burn a DVD
Once edited, burning a DVD (or Blu-ray) of your video onto a recordable (R) or rewriteable disc (RW) is an ideal way to watch back your footage, and it makes a great gift for friends and family. The option to add chapters and utilise your player’s remote control to navigate through footage is an extra bonus too. It’s a simple process that is free using Windows DVD Maker, or alternatively iLife 09 (£70) for Mac contains the iDVD application. Open source programs such as DVDFlick offer a viable alternative that won’t cost you a penny either. It’s worth remembering that DVD doesn’t support HD footage, whereas Blu-ray does – though recordable Blu-ray discs and players don’t come cheap as yet.
What you play your videos back in can make a real difference to the way they view – we’ve probably all seen jumpy motion or nasty pixellation when playing movies on a computer. This can be down to a poor media player not dealing with the file well, or it could be a low-spec machine or power-hungry operating system hogging the CPU’s capabilities. To get the best out of your videos it’s best to playback using a well-established and effective player: among the most popular is Windows Media Player – Microsoft’s own that comes bundled with Windows; Quicktime – Apple’s proprietary program which is native to .mov format but has come on in leaps and bounds to deal with multiple formats; and RealPlayer – one of the first players to allow live streaming of video from the Internet. Also consider the VLC Media Player – it’s extremely quick to load, doesn’t take up much space and runs a huge array of file types, plus lends itself to third-party development for free given its open source status – it also comes high up the recommendation list.
Editing Video Files
At first glance, video editing may seem overwhelming. However, as with anything, once you get the hang of how the system works, dropping clips onto a timeline becomes very easy. You can apply more or less the same colour correction tools that are found in Photoshop or Paint Shop Pro, such as Colour Balance, Hue/Saturation, curves and so on. Add in a music track and then export the entire production to a DVD or YouTube. Popular start-up applications include iMovie (Mac), Adobe Premiere Elements, and Corel Video Studio X2, among others. For the user who doesn’t want to become involved with video editing, then you can simply link up the camera to a domestic TV set via the HDMI output and watch your movie clips from an armchair.
Your Essential Guide to DSLR Video – Top Tips of DSLR video
Remember standard TV and DVD don’t display high definition (HD) at full resolution. For HD 720 and Full HD 1080 you’ll need the right HD display for optimum viewing. Web video uses a much lower resolution.
Invest in memory.
If you intend to shoot a lot of short sequences then your memory cards will fill up, and fast. One minute of 1080p footage (MPEG4) will take up at least 300MB of space, so it’s worth carrying around spare cards – ones new and fast enough to keep up with the large stream of data too.
Look for the right frames per second (fps).
Video needs to record upwards of 24fps for movement that appears smooth to the eye. For UK playback, 25fps or 50fps is the optimum to be compatible with PAL – the UK display standard.
Your Essential Guide to DSLR Video – DSLR HD Video buying advice
At the moment HD may appear slightly ahead of its time, but doesn’t it make a nice change to buy something that’s ready and waiting for tomorrow’s technology? With so much emphasis on HD TVs and displays, it makes most sense to capture at the best possible quality. In terms of DSLR cameras offering HD video capture, there are a few main contenders: The Canon 5Ds Mk II offers Full HD (1080p 30fps), whereas the Nikon D90 has HD (720p 24fps). The Panasonic Lumix GH1 offers Full HD (1080p 25fps) and 720p (50fps), this together with a small body and stereo microphone makes it a very desirable camera with the ideal PAL-compatible frame rate. The Nikon D90 (and D5000) or Canon 500D offer the best value for money, though for video and still image quality the Canon 5D Mk II has the edge.
Canon EOS 5D mk II
The daddy of the DSLR video world – the Canon EOS 5D Mk II offers 1080p Full HD video at 30 frames per second. With the ability to attach a wide array of Canon lenses, it’s possible to shoot from wideangle through to telephoto with all the glorious benefit of having a full-frame sensor and the superb shallow depth of field possibilities this offers. Manual focusing and autofocus are both possible when recording. You can even add an external microphone. Many tout the 5D Mk II as the DSLR that can dethrone many digital video cameras; we’ve even heard of pros shooting music videos with it!
The first compact camera with an OLED screen – a new organic light emitting diode format that reproduces colour and blacks at a contrast level way beyond LCD. Additionally OLED uses much less energy, in turn leading to a longer battery life. Samsung’s WB1000 records 720p video at 30fps and you can enjoy high-quality playback for even longer. Excellent stuff.
Casio Pro EX-FH20
Not content with shooting at 30fps, the EX-FH20 delves into super-high frame rates – making it possible to shoot at 210fps (480 x 360), or even 1000fps (at a more letterbox-like 224 x 56). Imagine the world in super slow-mo; a whole new range of creative possibilities.
One of the first incarnations of the Micro Four Thirds system, the Lumix GH1 has been causing a stir. Not least because it can record 1080p/25 HD video, ultra-smooth 720p at 50fps and even has a stereo microphone. The GH1 is much smaller than a standard DSLR – so it’s less obtrusive than even some compacts and is already making waves in Japan; expect much the same when it hits the shelves here this summer.