Originally posted by leekil The originally stated hypothesis (as I interpreted it from the OP), is that the SR cameras are more heated not due to the *use* of the SR mechanism, but that the design requirements of the SR mechanism result in a sensor that is less physically connected to the rest of the camera. In this case, the rest of the camera has less capacity to act as a heat sink to prevent the sensor from heating up as much or as fast.
Yes, that seems to be what the "internet pundits" I have read are saying. (I'm not naming them because facts should be independent of personalities...but I can if it adds to the fun!)
Originally posted by Fogel70 In Pentax SR the sensor is mounted on a quite large metal frame that sits between two metal frames that are connected to the body. So this might actually be better for cooling the sensor than on many cameras without IBIS.
SR itself may also improve cooling a little as when sensor is moving the airflow will increase over the sensor.
Both are good points. Furthermore, if those metal frames roll around on tiny ball bearings (that's what it sounds like to me!) when they are pushed and pulled magnetically (is it like a voice coil in a speaker?) then there could still be some thermal conduction to the body of the camera, which in the case of the K-3(II), KP and K-1 (and K-5, K-7, etc) is almost all metal. [I have read that the sensor floats magnetically. But if that were so why do I clearly hear noise when the SR is active (e.g., during live view with telephoto lens)?]
Frankly, if the sensor were indeed thermally isolated from the rest of the camera,I would expect that the camera would have a tendency to shut down from overheating before the 25 minute time limit is reached while recording video (during which the sensor is constantly being read but the SR is not active). Has anyone ever reported that for Pentax K series DSLRs?