[JJ_SO]

All sensors have glass in front of them, I'm aware of that.

That's not what I'm talking about.

I'm talking about a mechanism that would automatically protect the sensor itself so it would not be exposed when changing lenses.

It would prevent (or at least help prevent) dust from coming in and reaching the sensor.

Dust is obviously becoming more and more critical with high resolution sensors and keeping sensors clean of dust is not easy to achieve when often changing lenses in outdoor environments with potentially not clement weather.

 

By putting in another moving element - and that's what I WAS already talking about   - you'd just increase the ammount of glass or other surfaces receiving, carrying and shaking dust inside the sensor. At one moment that mechanism has to open up - and where do you think, will the dust go then? It's not as if that mechanical element would act as dust magnet and keep the particles fixed.

 

Also, sliding doors always suffer of wear. If no dust comes from outside, little particles from the guiding elements will fall in the then difficult to clean volume in between sensor glass and "shutting curtain". I rather prefer good access to the sensor's surface and clean it from time to time. Usually these particle are only critical on bright areas with not much structure - that makes it easy to  repair.