Are there cameras which can continuously shoot for an unlimited amount of time? [duplicate]

Question

I've noticed that the quality of pictures on my DSLR is considerably higher than the quality of video. This got me thinking that if one could continuously shoot at high FPS, it should be possible to shoot "videos" of extremely high quality. Obviously you'd need to capture the sound separately, but it shouldn't be a problem. However my own cheap camera can do a 10-shot burst at most and as far as I know most DSLRs have similar restriction.

Is there a DSLR on the market which can do high-speed bursts for an unlimited (or considerable) amount of time?

Answer 1

Here are some of the reasons while still picture quality is considerably higher than video:

• Resolution Even 4K video is only about 8MP. Standard HD (1920x1080) is only about 2MP. Most current DSLRs are upwards of 20MP. All of that resolution comes at a price, though: larger data rates per frame. And it's not just the total number of pixels per frames, it's also how they are compressed and saved.
• Compression Video tends to be much more compressed than still images. This is because some of the artifacts caused by heavier compression average out from frame to frame. That's a lot less of a problem at 24fps than it is for a single still image, so video codecs can get away with higher compression.
• Codecs Still images are recorded with all the information needed to display an image in each frame. Most video codecs record an initial frame and then record only the differences between each frame and the frame immediately preceding it in each successive frame. Again, the lower image quality of each individual frame is not noticeable at 24fps. The resulting savings in terms of data rate can be quite substantial.

It works out that about 20-30 HD video frames are roughly the same size as a single 20MP RAW file. To put it another way, you can store an entire second's worth of HD video in the same space as ONE 20MP RAW file. And that is only 1920x1080. 4K would require the same as one 80MP still image (It's both twice as wide and twice as tall in terms of resolution, so there are four times as many total pixels). Even at JPEG compression that's still about a 20:1 ratio.

So to get a camera to record video at still image quality, the data rate would need to be increased by a factor of about 24X! To record even one minute of video at 20MP and 24fps using still image compression and codecs would require the same amount of data as 1,440 frames of a 20MP image! Current memory card technology isn't even close to that kind of throughput.

Then you would need to have a memory device capable of storing all of that data. You could fill up a 128GB memory card in only a few seconds of recording. You've also got to consider the power needed to process that kind of data rate in a DSLR sized package. The best cameras from Nikon and Canon can go about 2,000 frames on a single battery. The same amount of data required for 2,000 raw files will get you about a minute and one half of 20MP /24fps video.

Answer 2

The Canon 1D X Mark II can do essentially unlimited JPEGs bursts. However... at 14 fps and non-trivially sized files, your limiting factor is going to be the size of your memory card(s) and how many shots you can take before your battery is dead. Also, this is "only" 14 fps, which isn't going to cut it as a video.

Answer 3

tl;dr

The video can never catch the resolution and bit depth of the still photography. When shooting stills you have plenty of time to collect and process hi-res hi-quality image (huge 3D matrix) while in video you are restricted to 25 frame-per-second rate.

When shooting action stills you have 1 to 10 us for exposure, 200 us for processing and seconds to store the burst of images you have shot. In video you have only 40 us for exposure, processing and storing alltogether. For slo-mo videos you are limitted to 0.3 us capture-process-store period for 3,800 fps video.

Whenever the video reaches a milestone (4K for example), still photography was there years ago.

---

The restriction of bursts is in buffer size and in data transfer speed.

Just make rough estimate; let's have 18MPx camera with 14bit colour depth and 5 fps burst.

One RAW file is 21-27 MB large.

When shooting 5 frames per second, you have to transfer 105 - 135 MB per second that is 840-1080 Mbps. For a video you are looking for 24-25 frames per second to have continuous feel. That means 4.0 - 5.4 Gbps data flow.

That's why there is buffer memory that stores the data while slower writing to the memory card is being done. And that's why cheaper cameras can do small bursts while the more expensive ones can do longer bursts - they have much larger buffer.

If you add some compression algorithm in the line, you have to add the processing time (another limit for the frame rate) but you can reduce the data rate depending on the compression algorithm used.

Note on data transfer:

The most common way to connect DSLR to PC is USB 2.0 with maximum speed of 480 mbps (not even close). USB 3.1 gen.1 can transfer data with speeds up to 5Gbps (close). USB 3.1 gen.2 and USB-C are planned to reach speeds up to 10 Gbps.

You have to write all the data down; commonly used SD cards are capable of various transfer speeds:

SD UHS 1 class guarantees 10MBps = 80Mbps write speed;
SD UHS 3 class guarantees 30MBps = 240Mbps.
SD V90 class guarantees 90MBps = 720Mbps.
Fastest CompactFlash card can reach 160MBps with 65MBps guaranteed (1280/520 Mbps).
The fastest XQD 2.0 cards can reach 400MBps (3.2 Gbps). The fastest CFast 2.0 cards can reach 490MBps (4.0 Gbps).

Hard drives connected via obsolete PATA interface can reach 536Mbps speeds,
Hard drives conencted via SATA 3Gbps or SATA 6Gbps can theoretically reach 3 or 6, respectively, Gbps. SSD drives are advertised with speeds up to 680 or 1040 Mbps writing speeds. Old hard drives use buffers, I cannot tell what are their speeds when the buffer runs out (the largest buffer I can find is 256MB; the room for 10 RAW frames!).

You can see that no storage is capable of writing such ammounts of data steadily for long periods and only the high spec USB 3.2 and USB-C can handle such data rate.

Only the 256 GB Delkin card is capable to be fairly close to the desired speed. Its memory runs out in 7 minutes and 45 seconds of video.