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This is a bit of an philosophical question, so bear with me.

I have an "old" Canon EOS 30D. Some models later, Canon started releasing EOS cameras with video capture capability.

Is there anything intrinsically limited about the hardware of the 30D that means it couldn't capture video? If the video stream was sufficiently low-res, low-framerate, high-iso, and uncompressed, could the hardware theoretically capture the light over time? Or is the sensor unable to count light levels continuously? Perhaps video capture would require a vastly more powerful chip for encoding the video stream?

This is not a practical question! I'm not asking how to get my 30D to take video (of course!), I'm asking what is the main reason that it can't.

Any takers?

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3 Answers 3

up vote 9 down vote accepted

Older models like the 30D simply lack the hardware required to continually read from the image sensor. These models cannot support video, except at very low framerates by opening and closing the mechanical shutter continuously.

Since the introduction of live view with the 1D mkIII in 2007, Canon DSLRs have been equipped with an electronic shutter and can continually read from the sensor and display the image on the screen for focussing. Subsequent models (1D/s mkIII/IV/X, 5D mkII/III, 6D, 40/50/60D, 450/500/550/600/650D, 1000/1100D) are thus intrinsically capable of producing video (since it's essentially the same thing, just output to a memory card instead of the screen), all that is required is the software to take this data, encode it and store it on a memory card.

Models prior to the 5D mkII (1D/s mkIII, 40/50D, 450D, 1000D) don't have this software as standard but have the potential to record video via a firmware update, or an via HDMI with an external recorder, though these methods will likely have some drawbacks.

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There are some firmware (NOT by Canon. Search for "magic lantern") available which allow to turn on the video recording on camera which don't natively support it. I have not tried them, but they are reported to work on the 50D. I suppose that it would be possible for other models, too, but since it is an unsupported-"void your warranty"-DIY approach, it has not been implemented for each and every model.

You can look for video on youtube which shows the thing in action.

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As noted in @Itai's answer the main problem - even with alternative firmware - is the sensor physically overheating. –  cadmium Nov 28 '12 at 23:20

No. Being able to record video was an evolution in technology and it took a long time to get there.

To understand why you have to first know that video is a sequence of images captured continuously at a steady frame rate and sustained over a relatively long interval.

Since video would not be very useful without seeing what you are filming, Live-View is a prerequisite for video and that feature had to be invented and perfected. The first implementation was B&W and lasted at most 1 minute courtesy of the Fuji Finepix S2 Pro. Olympus made it color with their E-330. It was able to focus thanks to a second sensor in the viewfinder chamber. Later, contrast-detect AF was added.

The implementation of Live-View faced two challenges, one is to get a feed at 24 FPS to keep the display updated and the other is to make sure the sensor does not overheat while doing that. A lot of innovation in electronic-shutters and power consumption was needed to work through those and modern DSLR will still occasionally give the over-heating warning after Live-View or Video is used for too long.

One you have Live-View refreshed at a reasonable frame-rate (24 FPS is the minimum standard rate for video) and sustained for a while (at least a minute to be useful), you have to encode and stream the resulting video to the memory card. You need to make sure all the data paths to the memory card support the bandwidth needed by the video codec. Video codecs are CPU intensive operations, particularly modern ones to work with HD video and require powerful processors.

A few camera attempted to get there before everything was perfected but results were not very useful. The Pentax K20D for example could stream 20 FPS video at somewhere between VGA and 720p resolution but there was NO preview at all, so you were shooting blind.

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Thank you for this comprehensive answer that details the key tech advances that made this possible. –  Kaushik Ghose Sep 21 '13 at 21:11

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