The Nikon D5100 greatly upgrades the HD movie capabilities of its predecessor, and even builds upon those offered on the higher-end D7000. As such, where the old D5000 only offered 720p HD video at 24fps, the new D5100 boasts the choice of 720p or 1080p, each at either 24, 25 or 30fps; that's already one-up on the D7000 which only offers 1080p at 24fps.


Where the old D5000 was manual focus only when filming, the D5100 also inherits the continuous AF capabilities of the D3100 and D7000. This really separates it from Canon which doesn't attempt to continuously autofocus while filming.


The D5000's Motion JPEG encoding has also been dumped in favour of the much more modern and efficient H.264, and Nikon's also equipped the new model with an external microphone input. Annoyingly there's still no formal manual control over exposures, but like its predecessor, the D5100 can 'inherit' the aperture selected prior to entering Live View if desired.





 


Overall the addition of 1080p, multiple frame rates, continuous AF, more efficient compression and a microphone input make for a significant upgrade over the earlier D5000. Indeed while it may be lacking the manual exposure control of the D7000, the support for 1080p at variable frame rates along with an articulated screen, arguably makes the D5100 Nikon's most flexible movie-making DSLR to date. There's certainly lots to discuss below, but before I launch into the fine details, let's check out our first clip.



n the handheld clip above the first thing to notice is the lack of vertical streaking around the sunlight reflections on the water - this is a benefit of a camera with a CMOS sensor. But if you're playing the file with audio, you'll almost immediately notice a faint squeaking or scratching in the background. This is the sound of the kit lens constantly being refocused by the D5100's new AF-F continuous autofocus mode, and it's quite audible on this clip.


Unfortunately in this example, the continuous autofocus isn't doing a great job either, regularly searching for a subject with sufficiently strong contrast for it to lock onto. So while the actual video quality itself is fine, the continuous AF option hasn't performed so well in this example; indeed disabling it would have probably produced better results. But before you write-off the D5100's AF-F mode, check the clips below as it can work reasonably well under the right conditions.





With this first example out of the way, let's take a look at the specifics. Like previous Nikon DSLRs with video capabilities, the D5100's Movie mode works as an extension to Live View. So first you'll need to enter Live View by flicking the new spring-loaded lever around the mode dial. Then to start recording, simply press the red button by the shutter release, before pressing it again to stop. You can take a photo with the D5100 while filming, but there's a pause between pressing the button and the image being captured - and it will also stop your recording. Note: the second screen grab
on the left is taken from our D3100 review as the D5100's AV output wasn't active while recording.


Unlike Canon's latest models, there's no dedicated manual exposure mode, but like earlier Nikon DSLRs, the D5100 can inherit the aperture selected in Aperture Priority or Manual modes prior to entering Live View; this value can't however be adjusted once you're filming. If you try, the values certainly change on screen, but they don't appear to be applied to the current recording. The ISO can also be manually set prior to entering Live View, but the shutter speed remains automatic throughout.


The D5100 offers a wealth of movie quality settings: 640x424 at 25 or 30fps, 720p at 24, 25 or 30fps, and 1080p, again at 24, 25 or 30fps; like Canon's models, the 24fps options are always available, but you'll only see either 25 or 30fps options depending on whether you've got the video mode set to PAL or NTSC. The D5100 also lets you choose between two compression levels for each of the quality settings above. Note this is the first Nikon DSLR to offer 1080p at anything other than 24fps, although it's still lacking the higher 50 or 60fps 720p options of the Canon DSLRs, which allow slow
motion playback in a 24, 25 or 30p project.


Each of the 1080p frame rates consumes 18Mbit/s with the quality set to High or 10Mbit/s when set to Normal. Switch to 720p at 30 or 25fps and it'll consume 10Mbit/s in High quality or 6Mbit/s in Normal quality. Set 720p to 24fps and the rate decreases a little to 8Mbit/s in High or 5Mbit/s in Normal quality. Finally the 640x424 mode consumes 4Mbit/s in High or 2Mbit/s in Normal quality. So in real money, you're looking at about 2.5 Megabytes per second in the best quality 1080p mode.


The maximum recording time is 20 minutes, double that of the D3100 and four times that of the D5000. Even at the best quality setting, you can film 1080p for 20 minutes and still comfortably make it under the additional 4GB file limit. Nikon recommends using a Class 6 card or quicker for HD movies; I used a Lexar Professional 16GB 133x SDHC Class 10 card in my tests with no problems, and confirmed the 20 minute limit with a High Quality 1080p file measuring 2.73GB. Note Canon's HD movie modes are much more memory-hungry, consuming over twice as much data at 330MB per minute thanks to higher
bit rates - so their 4GB file size will be reached after around 12 minutes of HD filming. This gives the D5100 an advantage as not only can it record for longer per clip, but the file sizes are smaller too.



The video and audio are encoded using H.264 and stored in a Quicktime MOV wrapper - this is the same compressor as Canon, but used at a lower bit rate for smaller file sizes. Like Canon's MOV files, we found VLC Player proved best for playback under Windows, although the latest Media Player also worked fine.

The D5100 has a built-in mono microphone, and in an important upgrade over its predecessor, a 3.5mm jack for connecting an external stereo microphone. Nikon now offers its own ME-1 microphone which mounts on the hotshoe, or you could connect a third party model like the Rode Video Mic Pro. I tried out the latter and it worked just fine on the D5100, although sadly even its highly directional nature was insufficient to hide the audible grinding of the kit lens autofocusing.




The audio recording levels can be set to automatic, or to low, medium or high sensitivity; alternatively you can disable audio recording if desired. It's good to have the choice of recording sensitivities, but sadly there's no level meters for immediate feedback.



n the second clip, above, I've locked the D5100 to a tripod, disabled VR and AF on the kit lens and smoothly panned from left to right. With the Continuous AF disabled, it's quite a relief not to hear the scratching sound of the kit lens focusing in the background, and it allows you to appreciate the quality of the video on the D5100. Like all DSLRs though, zooming smoo thly, even on a tripod, is a challenge, but I've included several adjustments towards the end for reference. Watch out for the wind noise as I point the camera towards the steamship, and also the sound of a dog snoring in the background...

Moving on, the third clip above was filmed handheld in a relatively dim bar with both VR and AF-F enabled. At first, the camera's AF system seems happy not to make any adjustments, but around halfway through, it kicks-in and once again the scratching sound, not to mention the visual searching becomes quite distracting - epsecially towards the end when it has to perform a broad adjustment. Once again, this clip works much better with Continuous AF-F mode disabled. On the plus side, the clip itself may be noisier than those filmed outside, but the noise levels remain relatively low and the detail high. Obviously given a lens with a brighter focal ratio, the results in low light can look much better.
 

One of the D5100's most impressive movie features, at least in theory anyway, is the Full-time Servo AF mode, inherited from the D3100 and D7000 and which delivers continuous autofocus while filming - something which continues to elude Canon's DSLRs. For example, while Canon's latest DSLRs technically support autofocusing while filming, it's a Single AF operation which is initiated by hand and takes several seconds to lock-on thanks to the leisurely contrast-based AF system. Theoretically you could just keep forcing a Canon DSLR to repeatedly perform this process in an attempt to keep the subject sharp during a clip, but it wouldn't look pleasant with constant visual searching, not to mention the sound of the lens doing it.

If you've watched the first clip above though, you'll know this is effectively what's happening with the Nikon D5100's AF-F mode, albeit the difference here is the camera initiates the AF process, not the photographer. The D5100's AF-F mode works exactly the same way in movies as it does within Live View. It immediately checks the selected AF area and if it's not sufficiently sharp, it'll use the contrast-based AF system to focus on it. Depending on the subject though, this could take an average of two seconds each time with the lens typically searching back and forth at least twice. If your lens has audible autofocusing, like the DX 18-55mm VR kit lens, you'll also hear this squeaky scratching sound recorded quite clearly in your movies. And if the subject regularly moves, the camera will keep trying to lock-onto it, which means your video could suffer from a lot of visual searching, and of course the sound of it too. My next clip better illustrates how the system works and what kind of response you can hope for.

 

The fourth clip, above, deliberately puts the new AF-F mode to the test. Here I moved the camera around, pointing it at various subjects near and far to see how the continuous autofocus coped. Give the D5100 some defined edges for its contrast-based AF system to lock-onto and it can actually do quite a good job. Sometimes the focusing searches a little, but at others it feels more confident as it locks-onto the desired subject. Indeed as the clip progresses, it's hard not to be at least a little impressed by the AF-F mode as it succeeds more than it fails. It may not be as consistent as a consumer camcorder, nor as confident as the phase-change AF on the Sony Alpha A33, but the D5100 still manages to keep the subject mostly focused as the composition changes, while the ambient background sounds mostly mask the kit lens's AF motor. This is an impressive capability for a camera that only has a contrast-based AF system at its disposal while filming (along with the challenges of a shallower depth-of-field than a camcorder); remember Canon's DSLRs don't even attempt to continuously autofocus while filming, making this clip impossible without constant manual adjustments. 


n the next clip, above, I've given the D5100 a more predictable subject to track with its continuous AF. I zoomed the kit lens to 55mm, adjusted the D5100's AF area to the middle, and kept it positioned over the Skyline logo on the cable car as it steadily approached. Like most contrast-based AF systems, the D5100 searches back and forth as it attempts to lock-on, and this is quite visible at several points during the clip. This is undoubtedly off-putting, but to be fair, the D5100 does manage to keep the logo relatively sharp throughout the clip, even when it's only a meter or so distant. Once again this is something which would have required constant manual focus pulling on a Canon DSLR. So while the D5100 continuous AF during filming may not live up to the experience of a consumer camcorder (nor the unique capabilities of the Sony Alpha A33), it remains a very impressive attempt given the available resources.
That said, for subjects where the soundtrack was critical or the subject remained mostly at a fixed distance, I switched the D5100 to manual (or single) focus. When AF-F works well, it's pretty neat, but more often than not it spoilt our clips with its constant searching. Indeed once you've seen and heard the effect of the kit lens constantly search back and forth on clips, you'll find it some relief to simply switch it off.


In a first for any Nikon DSLR, the D5100 offers a number of special effects via a dedicated EFFECTS position on the mode dial. These all work for still photos, but some can also be applied to video. The first example, above, is for the Selective Color Effect, where you can sample one or more colours and adjust the tolerance, after which the D5100 turns everything else into black and white. Here I sampled the red hat on the bear and simply let the camera do the rest. It's really nice to see this effect applied on video with zero effort, and it seems funny to think back this was a major and much talked-about effect on 'Schindler's List' only a few years ago.

Another one of the D5100's special effects which can be applied to video is the Miniature option, an increasingly ubiquitous effect which simulates a tilt and shift lens for a toy-like appearance. This requires considerable processing, so can't be captured in real-time at 24-30fps, but the D5100 uses this to its advantage and captures processed frames at a slower speed. Then when played back, they speed-up, further accentuating the miniature effect. Like still images, the Miniature effect can be applied with three different focus window thicknesses - here I used the middle option, and zoomed the kit lens in.
That's all for the sample videos, now what about ergonomics and comparing the D5100 against its biggest rival?
Like all DSLRs, the D5100's body was never designed for heavy video use, and while the articulated screen allows you to more easily film at unusual angles, there's still the fact you're holding a body that's ultimately designed to be held up to your eye. One solution is to employ some kind of filming rig which provides easier controls and handling. Dedicated DSLR rigs are not typically cheap accessories, but I discovered an affordable alternative which works pretty well.


Simply connect one of the larger Gorillapods to the camera and bend the legs upwards into a U shape. Two of the legs can then be twisted into vertical handles on either side of the body, allowing comfortable two-handed operation. The third leg can either be folded underneath, or bent back to provi de an additional point of contact against your body, or even over your shoulder.


I found I could handhold DSLRs much more effectively with my 'Gorilla-rig', greatly reducing wobbles and allowing much smoother pans. And of course you can always fold the legs back for conventional operation. If this sounds appealing to you, I'd recommend using the largest Gorillapod Focus model, as its strength and rigidity ensures the legs won't bend out of shape when you're transporting the unit with one hand.


So with variable frame rates at 720p and 1080p, an articulated high resolution screen and an external microphone input, not to mention the opportunity to apply special effects while filming, the D5100 is a considerably more capable movie-maker than its predecessor; indeed as mentioned above, if you ignore the D7000's more definitive control over exposures, the D5100 arguably becomes Nikon's most flexible video-equipped DSLR to date.


It is however very important to compare it against the competition, and in particular its closest rival, the Canon EOS 600D / Rebel T3i. Both cameras may share 720p and 1080p recording at variable frame rates, articulated screens and mic inputs, but there are crucial differences to weigh-up.


In its favour, the D5100 offers continuous autofocusing during filming, and while the effect can be visually and audibly off-putting for some footage, it does work well in other situations. This is the key advantage all the Nikon DSLRs have over their Canon rivals. Lower bit rates also mean smaller files and longer recording times, with the D5100 filming for up to 20 minutes per clip, compared to around 12 minutes of HD for the Canons. Then there's those effects, like Miniature and Selective Colour, which can be applied while filming.


In its favour, the Canon EOS 600D / T3i offers 720p at higher rates of 50 and 60fps, which allows slow-motion when incorporated into a 24, 25 or 30fps project. The bit rates may be higher, but these in turn mean fewer compression artefacts, which may be preferred by higher-end videographers  for whom the 12 minute clip limit is more than enough. The wider screen means more if it can be devoted to the active area, and while the HDMI output is downgraded while filming, at least it remains active to drive external monitors. The EOS 600D / T3i also boasts live audio level meters for
immediate feedback, along with much finer manual adjustment. Speaking of manual, the Canon also offers full manual control over the aperture, shutter and ISO, even while filming. Finally, the EOS 600D / T3i features a neat Digital Zoom mode which crops a 1080p frame from the middle of the sensor for an immediate 2.5x boost in magnification with no loss of quality.


Ultimately a pattern should be emerging here: the video capabilities of the Canon DSLRs are more targeted to high-end videographers and pros, whereas the key features of the Nikon DSLRs will appeal more to general users. If you want proper and fine manual control over exposures and audio along with basic slow motion capabilities, go for the Canon, but if you're happy with the D5100's attempts to autofocus while filming and want longer than 12 minutes per clip, then go for the Nikon.


Before wrapping-up though, it's not a two-horse race. If decent continuous autofocus is your priority while filming, then Sony's SLT A33 and A55 or Panasonic's Lumix GH2 do a much better job than the Nikon DSLRs and should become your top choices.


Now find out how the D5100 compares against its rivals in my Nikon D5100 image quality and Nikon
D5100 sample images pages. Alternatively if you've already seen enough, head straight to my verdict.

Источник: http://www.cameralabs.com/reviews/Nikon_D5100/movie_mode.shtml