The problem with 5fps on film was, only 7 seconds of shooting with a 36exp film!
That's why they invented these
But yeah, to summarise:
Film problems with fast shooting: move the mirror fast enough, advance the film fast enough.
Digital problems with fast shooting: move the mirror fast enough, read the sensor fast enough, clear the sensor to black fast enough.
And there's also AF fast enough, and adjust the exposure fast enough, for both systems.
The 1D-non-s line has a mirror that can move at 10fps, but it's a smaller mirror. It can also read and clear/reset 16MP at 10fps, with 2-year old tech.
The EOS 1V did 10 fps with a FF mirror over 10 years ago, so we know FF mirrors can at least be made that fast.
Just a comparison of bandwidths for a minute:
my 7D can do 18MP at 8fps, with a random sample of 331 .CR2 files (min 15.8, max 31.0MB) i've got handy, they average at 24MB each, so that's 192MB/s. 15-shot (rated) buffer, means 360MB (probably smaller, 256MB? because it clears space as it writes to the card). 7D announced 1st sept 2009.
I don't have a 1D4, but we'll pretend .CR2 files average out 16/18*24=21.3MB each. At 10fps, that's 213 MB/s. With a (rated) buffer of 28 raw frames, that's 598MB, so probably a 512MB buffer. 1D4 announced only a month and a half later, 20th oct 2009.
Now, in a completely unscientific comparison, courtesy of Tom's Hardware
, about the time the 7D & 1D4 were announced, desktop computer RAM was just less than $100 for 6GB of ddr3-1333. 2 years later, now we get 8GB of ddr3-1866 for $75
. Size up 30%, speed up 50%, cost down 25%.
So that's computer ram, of course, but gives a nice indication of trends.
Basically, what i'm saying is, that it wouldn't be much of a reach to put a 1GB (or double the 1Dmk4) buffer in tomorrow's camera, without affecting the price or size too much.
What if it's a Foveon-type, sigma-type, triple-well-non-bayer (what are we allowed to call them?) sensor, at 18MP? In short, keeping the rest the same (bits-per-pixel), it's going to triple the size of the RAW file, 60-80MB won't be unrealistic.
Triple my 7D's .CR2 average-size gives 72MB. At 12fps that gives 865MB/s. For a 12fps burst with a 1GB buffer, just over 15 shots will fill the buffer. Over-rate it for extra space gathered by emptying the buffer to the card, maybe we could get a 17-19 shot burst before that damn 'busy' light flashes.
That's barely 1.5 seconds of action. Is that acceptable? my 7D gives 2 seconds of action, the 1D4 gives nearly 3 seconds in a burst. For the theoretically-much-better colour detail from a non-bayer, there will be trade-offs, where your preference lies depends on your opportunity-costs (and I won't bore you with that, unfortunately i've got both an electrical engineering and an economics degree).
As for the issue of draining the charge and resetting to black that Joseph picked up on, I never though of it and it makes sense. Not only do you have to read the charge-level, throw it through your ADC and write to the buffer, then you have to clamp the sensor to ground to clear everything before the next frame, or you get ghosting (or just noise in general).
So, another unscientific comparison using consumer CPUs. Sept 2009 saw the release of the Core i5/7 Lynnfield on 45nm. Today we get the 32nm Sandy Bridge. Without comparing those two too much, in short, transistor sizes are going down, gate capacitance gets less so switching gets faster, power consumption goes down, etc. I've no idea what sized process Canon uses for their sensors, but it's got to be shrinking fairly quickly. Make a 5Dmk1-specced sensor using today's tech, and the noise will be noticeably lower just from the tech improvements, transistors and wiring between the photosites will be smaller, meaning relatively-larger photosites, add in gapless microlenses and any other tech canon's though of in the last 2 years that they haven't released yet, and you see where i'm going.
As for the other things, like AF. I'm not sure where I posted it previously, but you may all be interested in what the Canon Camera Museum
has to say:Even as innovations like 45-point Area AF and cross-type AF points have led to more compositional freedom and broadened the possibilities of photography, we are still devoted to developing in the near future AF technology that will focus where you want it just by thought alone without any physical operations. This â€œdream AFâ€ will astound you all.
"Dream AF", by "thought alone". OK, i'm not imagining an ESP-Grip add on or anything. It could be the return of Eye-Control. It could also be marketing speak for some abilities i pondered earlier, like multiple-exposure-without-mirror-dropping predictive AF, or read-the-image-sensor-as-it-takes-the-frame and cross-check with the AF-sensor, and combine the two results for more accurate AF. Or it could be a pellicle mirror with full-time stills- and video-AF.
As for the other ones, move the mirror fast enough and exposure-adjustment, they're the easier of problems to overcome. Materials-engineering has advanced a lot in the 12 years since the EOS-1V, just on the mirror-alone i wouldn't doubt 20fps is possible these days with a realistic-mirror-lifetime...