Why would I want an external recorder/monitor?

Not everyone wants to shoot video, so it may seem unthinkable to spend around $1000 on an external video monitor/recorder. However, others find it opens up creative challenges every bit as satisfying as stills photography.

The more you shoot video, the more you’re likely to encounter (and find yourself needing) tools that are rarely provided on stills/video cameras. We’ll be shooting with a couple of the more common models over the coming weeks to see how they compare, but first we wanted to give an overview of why you’d even consider using one.

Why would I want an external monitor/recorder?

As the two-part descriptor suggests, there are two main benefits to using an external recorder: to get a bigger, more informative preview as you shoot and to capture better quality footage.

Recording

In terms of recording, the benefits come from a number of factors.

Understandably, most stills/video cameras have processors designed primarily for stills, and they also have to make significant compromises in the name of battery life and thermal management, since video isn’t their primary role. Also, for the most part, they’re designed to produce amounts of data that are manageable by consumers, and at bit rates compatible with (relatively) slow memory cards. This typically means heavily compressed video, usually using what’s known as a GOP (group of pictures) video codec, which only records a full image at select key frames while interpolating the in-between images based on changes between frames. H.264 is a common example of a GOP codec.

"As the two-part descriptor suggests, there are two main benefits to using an external recorder: to get a bigger, more informative preview as you shoot and to capture better quality footage."

External recorders, by contrast, are dedicated video capture devices built by companies that specialize in video capture. So, while they can’t improve the level of detail that your camera initially captures, they leverage the fact that your camera often captures more detail than can be recorded using the internal codec. As a result, you can capture video with fewer compression artifacts, and usually in formats that work smoothly with major editing software, such as Apple’s ProRes and Avid’s DNxHD and HR.

For example, most cameras output a more detailed 4:2:2 stream over HDMI, rather than the simpler 4:2:0 footage they can themselves capture and compress. Meanwhile the Fujifilm X-T2 will only output Log footage over its HDMI socket. Other cameras, notably Panasonic’s GH4 and 5, will output 10-bit footage and can’t capture their very highest quality footage internally.

External recorders also often support SDI connectors, a more robust type of connection typically used on pro video cameras. The latest recorders support Raw footage over SDI which means the recorder can continue to serve you if you move beyond your current camera.

Camera Frame Rate Codec Bit depth / sub-sampling Bitrate
Panasonic GH5 UHD/24p h.264 10-bit, 4:2:2 400 Mbps
Sony a7S II UHD/24p h.264 8-bit 4:2:0 100 Mbps
Olympus E-M1 Mark II DCI/24p h.264 8-bit 4:2:0 237 Mbps
UHD/24p ProRes 422 10-bit 4:2:2 471 Mbps
UHD/24p ProRes 422 HQ 10-bit 4:2:2 707 Mbps

Similarly, external recorders often have better audio capture capabilities than those baked into the mass-market capture formats used in many cameras. As with the video footage, this is primarily a case of having more space dedicated on the screen, lower levels of compression and a wider range of settings and connectors.

Monitoring

The monitor side of things, there are a lot more benefits than just having a bigger screen to see things with, though this in itself is valuable. The ability to see your scene on a larger screen makes it easier to spot small, distracting objects and check precisely where your focus is set. It can also help you better visualize the way your final footage will look, helping you make creative decisions such as choosing how much depth-of-field you want.

It’s also common for monitors to offer overlays and composition aids. For example, framing guides that show crops for different aspect ratios can be helpful if you intend to publish your work in something other than the camera’s native aspect ratio.

Also, freed from having to share battery power with so many other functions, external monitors can often be run brighter than the rear screen on your camera, making it easier to shoot outdoors.

Boxes full of tools

But just as significantly, external devices often include useful monitoring tools that go beyond those offered in most cameras, both in terms of the range of tools available, and the precision with which they can be configured.

It’s becoming increasingly common for cameras to offer focus peaking, to check where the point of perfect focus is, but zebras, which highlights an area of a certain brightness, are still not universal. External recorders offer these features, often with greater control over their settings. The ability to choose to highlight a typical skintone brightness or everything exposed over 90 or 95% brightness, makes achieving consistent exposure much easier.

Focus peaking is becoming increasingly common on cameras, but external monitors can offer more subtle control over color and threshold, to make it easier to fine-focus.

The other feature common on external recorders that we’ve only seen on a couple of cameras is the ability to apply color and gamma curve correcting look up tables (LUTs) to Log video in real time. This means that you can shoot gradable, but washed-out-looking, Log footage but with a preview that approximates the finished result, so you end up looking at something much more visually meaningful.

‘Scopes

There are a series of exposure and color analysis tools widely used in video production, collectively known as ‘scopes.’ These are very rare on contemporary stills/video cameras, but are hugely useful for assessing your setup.

A waveform display is a tool to help visualize luminance/exposure. It’s common on pro video equipment as well as in video editing software. Rather than a histogram, which just tells you how many pixels hold each brightness value, a waveform tell you where those pixels occur in the image. The waveform diagram shows the brightness values for every column of pixels in the image: dark at the bottom, bright at the top.

Videographers like to use waveforms because it’s easy to visualize both exposure and contrast across the frame. This is particularly helpful for judging exposure at a particular location, such as a subject’s face. It’s also pretty common to have a choice of Luminance or separate R,G,B waveforms (known as an ‘RGB Parade’), for judging color balance and per-channel exposure.

The luma waveforms shown here are representing the ColorChecker on our test scene. There’s a thin, bright peak on the far left, representing the sliver of white that just crept into shot, then there are six columns representing the six columns of color patches on the ColorChecker.
Look closely and you’ll see that the pattern of the left-hand three columns getting progressively shorter continues into the right-hand columns: these are the progressively darker greyscale patches along the bottom of the ColorChecker.

The other common video tool is the Vectorscope, which can be used to evaluate color information in the image, such as hue and saturation. Getting accurate color straight out of camera (as well as matching it between shots) is particularly important when shooting video since Raw video capture hasn’t yet arrived in hybrid cameras. It’s a bit like shooting JPEGs – you only have so much latitude to adjust things in post.

False Color paints regions of the image to reflect their brightness. There’s a fairly standard scale, red for clipped whites, purple for crushed blacks, green for middle grey and pink for skintones.

Finally, one feature we’ve not seen on any camera yet is False Color, which is a little bit like having multiple zebras active at the same time. Most brands use a similar scheme in which tones around middle grey are painted green, one stop above this (the approximate brightness of Caucasian skin tones) is painted pink, near clipping is yellow, clipped is red, near black is blue and crushed black is purple. The result is a riot of color but with a bit of experience, it gives you a very easy way to interpret your exposure.

Workflow benefits

The net effect of these features quickly add up to provide benefits throughout the video workflow. If you can capture footage using a codec favored by your choice of editing software, you can usually speed up the process of importing by avoiding the need to transcode.

Similarly, the use of the fastest memory cards or still-faster SSDs maximizes transfer rates when it comes to transferring large video files to your editing computer. Again, with a project that takes more than a handful of clips, this is a huge time-saver.

Some external devices let you review and tag your clips before you get back to your computer, again speeding up the initial step of organizing your footage.

It’s not all good

As you’d expect, there are disadvantages to using external recorders, too.

Although each of the tools offered make it easier to set your shot up perfectly, this more precise way of working can also risk slowing you down. Also, the added weight and bulk of carrying a second device around with you makes it much harder to run-and-gun with an external monitor.

On top of this, it’s much less likely that you’ll go unnoticed. Even a relatively small monitor/recorder makes your setup look more professional and consequently more obtrusive. This is not the look for Guerrilla film making.

One downside of off-camera recorders is that it’s a bit harder to blend into the scenery and remain unnoticed.

Also, although external devices don’t need to share their battery power with so many other functions, it still takes a lot of power to run a screen and capture and compress video. Even the models with fans tend to run hot and hit their batteries hard, meaning you’ve got more recharging to plan and worry about.

But, given the amount of planning that goes into anything beyond the simple grabbing of clips, this additional consideration isn’t that onerous. For a bit more planning and setup time, an external recorder can help you get the very best out of your camera.

$1000 isn’t a trivial amount of money but, for a great many photographers, it’s an amount they’d justify spending on a lens. Just like a lens, an external recorder can help expand the range of things you can do with your current camera. It’s also brand agnostic, so unlike a lens, it’s very likely to work regardless of what camera you buy next, and will help boost the quality of everything you shoot, not just the things you can use a new lens for. And that’s got to be worth it, hasn’t it?

from Articles: Digital Photography Review (dpreview.com) http://ift.tt/2rhsg7Y
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