jrista said:
neuroanatomist said:
Don Haines said:
There is a third possibility...
To do 4K right requires 4 times the computing power as 2K video. That makes a lot of heat and drains batteries fast... and there is a real possibility that the problems with dissipating the heat make it impractical in a DSLR body unless you add in heatsinks, and that is a negative to all those using it for stills. Obviously, a 1D-C has the thermal mass, battery capacity, and radiative surface to handle this, but does a smaller body?
Does the Panasonic GH4 not do 4K right? It certainly doesn't have a large thermal mass or space for big heat sinks inside.
It does not, however it has a considerably more advanced, lower power sensor. Canon is still using huge transistors, and they are not even the more advanced kind of high efficiency multi-gate transistors we're capable of manufacturing today. Canon is really, really, REALLY far behind on sensor tech, and even behind just on general CMOS fabrication.
Yeah, I think a sensor fabricated with an older process using huge transistors IS going to create a lot of heat when operated at a higher speed. So I think Don's comment has a lot of merit.
hard to say. usually that is a function of "die shrinking" and die shrinking here wouldn't have a place because regardless of the geometry - the die is the same size - trace wiring is going to run the same distances regardless of the lithographic geometry. also usally these devices when shrunk run at a lower internal power - they require less - not really so with sensors, as you can't lower the voltage as that would have an effect of increasing noise percentage. Not only that but decreasing the geometry also has the effect if the wiring is the same distance, increasing the resistance, which would again be distributed as heat.
so while transistors that are switching in the millions of times per second will consume more power the larger they are, that is relatively immaterial to the other aspects of the sensor as well, and especially considering that the switching on a sensor is relatively pedestrian at best.
Canon's never had a problem with "dark current" and heat on their sensors which is usually exhibited at long exposures and sensitive applications such as astrophotography. as a matter of fact, they've always been some of the best, and are still favoured by astro photography.
there's also more prone to ESD, more electron loss, and a mydrid of other complexities surrounding smaller geometries - which is why you see all the ASP-C and full frame sensors using around 20+ year old lithography technology.
canon's KrF could easily handle current "high tech" sensors - but only their engineers know if there's any benefit, and i'm sure they have a better grasp on that than you and I.
with respects to the heat generation - most of that would be in DiGiC and whatever sub processor they are using for the codecs as the processors have to read through 4K worth of RAW data x 24-30 frames per second, debayer and apply tonal curves, and then write it out at 24-30 frames per second in the codec of choice.
they are image processing (or have to) around 200MB / second through the DiGiC processors - because it certainly just isn't coming off the chip and being written out onto a CF/SD card.
