DSLR cameras are big with lots of heavy metal for the chips (DIGIC etc) to use as a heatsink.

But mirrorless cameras are very thin and made lightweight to appeal their consumers.

This question came to my head when I learned A7R II overheats whenever used. So perhaps its a camera related problem and not a general characteristic of the mirrorless cameras?

  • 1
    Some mirrorless cameras are small and lightweight, some aren't.
    – vclaw
    Jun 15, 2019 at 16:57

2 Answers 2


Yes, overheating is a problem.

For Canon EOS RP, the 4K mode was limited to 24fps to not overheat.

Cameras with a mirror are heavierweight, so adding a small heatsink doesn't increase the weight as much relatively speaking (400g -> 450g is more significant than 800g -> 850g), so it's probably not a surprise that Canon EOS 5D mark IV can do 4K 30fps as opposed to only 24fps, even though EOS 5D mark IV is older than EOS RP.

The issue is not a camera related problem; all brand new cameras have the same generation of technology and the heat dissipation is therefore similar. Mirrorless cameras that are designed to be small and lightweight don't have as much options for dissipating the heat, and therefore, they are more prone to overheating.

  • It's not just weight, it also seems to be about air space inside the body. If one views Roger Cicala's recent teardown of one of Canon's new mirrorless bodies, one can see more air gaps behind the sensor than is typical in other manufacturers' slightly thinner bodies. Cicala theorizes the extra gap may be for heat dissipation or it may be to allow room for adding IBIS to a later body in the same line without increasing the size of the chassis.
    – Michael C
    Jun 15, 2019 at 22:34

Mirrorless cameras need to produce a live view from the sensor, so the sensor has to deliver data at a high frequency. This produces heat due to a large amount of pixels operating converters and circuitry. The heat production should not differ significantly from creating a movie with comparable frame rate. It was one of the reasons early DSLRs had no movie modes. Whether the sensor requirements of current-day cameras for the resolutions offered by viewfinders and screens are still an issue is debatable, particularly if they do sport movie recording modes. But it certainly was an important consideration at one time.

  • Both the sensor and the EVF produce heat.
    – Michael C
    Jun 15, 2019 at 22:35

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