4K Video for $400

Started Oct 23, 2012 | Discussions thread
mgrum
Contributing MemberPosts: 522
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Re: 4K Video for $400 + $25,000 + $5,000 + Time + Perspiration
In reply to Cy Cheze, Oct 30, 2012

Cy Cheze wrote:

Any 4k video will be worthless without a large 4k display, without a PC with sufficient spec to edit 4k video, or without the time and effort to make something that makes worthy use of 4k resolution. Of course, all is for naught if there is no audience with the bandwidth, displays, or players necessary to see it.

27" ultra def displays sell for under $1k, but they do justice to 4k only if the viewer is a few inches from the screen, which is not the usual viewing distance for video.

Use of large 4k screens will be limited to theaters, other commercial venues, or mega-McMansions until the prices come down from $25k to perhaps $2.5k, perhaps by 2016. Actual 4k content will lag too, so long as the requisite bandwidth is too expensive or there is no 4k Blu-ray. Upscaling of 1920x1080 video is not a good reason to get a 4k screen.

I have to repeat this every time 4k cameras are mentioned... 4k footage resized to 1080p will look a lot better than native 1080p, as most cameras that record 1080p only use one colour sample per pixel (bayer interpolation). It's like comparing a 2 megapixel Bayer sensor to a 2 megapixel Foveon. That's why the Canon C300 uses a 4k sensor to produce 1080p video.

You don't need a PC capable of editing 4k to benefit either, just recode the video to 1080p offline (you can set it going overnight if it's really slow).

The potential audience with the bandwidth/display/players necessary to watch 1080p (and thus benefit from full colour 1080p footage from 4k Bayer capture) is huge (HD streaming is all over the web).

No need for 4k displays to benefit from 4k capture.

A DSLR or SLT camera that shoots 4k video will be a problem for several reasons:

  1. High bitrate will entail tremendous heat generation and limited shooting duration, since sensors and memory cards may melt unless specially cooled.
  2. Narrow DOF and higher resolution will make satisfactory AF almost impossible, and manual focus pulling will be very tricky.
  3. Moiré and aliasing, aggravated by sensors with too many megapixels, will require filters that undo much of the added resolution.
  4. Any 4k video shot hand-held will look pretty bad, even on a high-end camera, making extra expenditure for a large 4k camera somewhat dubious.
  5. Hardly any clients of people who shoot commercial video and buy expensive cameras will pay them to shoot and edit 4k video, since they would have no way to use it at present.
  1. 1. The Canon 5D mkIII can shoot full resolution JPEGs at 6fps until the card is full, that means reading 5760 x 3840 x 14 x 6 = 1.9 gbps (gigabits per second) from the sensor, continually. Recording 4K at 24fps requires reading  4096 x 2048 x 14 x 24 = 2.8 gbps. So 1.9 gbps is absolutely fine with a no pro DSLR, but 2.8 gbps entails tremendous heat generation? At most I'd expect 50% more heat.
  2. You can always stop down, the larger sensor gives you better noise performance so you can stop down and up the ISO. Or use a wide lens for adequate DOF.
  3. Aliasing is much worse the more you skip lines/pixels, and worst when the [spatial] sampling frequency is low. More megapixels means less moire!
  4. 4k gives you more data to work with and more opportunity to apply software anti-shake, for example.
  5. Again, no need to be able to display 4k to benefit from 4k capture.

All these arguments are the same ones levelled against the D800, e.g. you'll suddenly need a tripod where you wouldn't need one before, nonsense. Aside from processing and storage requirements there is no disadvantage to increased resolution, even if it's harder to realise the full benefit.

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