On 2018-07-29 16:38, nospam wrote:
In article , Carlos E.R.
wrote:

I never understood well why a digital camera needed a mechanical mirror.

the same reason film cameras did, so that the viewfinder has an optical
path through the lens.

while digital viewfinders are much better than they used to be, they
are still not as good as a ttl optical viewfinder, particularly with
sports and low light. there is also no battery drain with an optical
viewfinder and focusing is faster.

And the digital display is actually seeing what the "film" is seeing. It
might in fact apply the digital processing that the final photo is going
to get so that the photographer can best decide on settings and timing.

The point of the SLR was that the photographer would see the same as the
film was going to see. Well, the digital display is one step further on
that road.

And as Tims points out, there can be a display inside the eyepiece instead.

--
Cheers, Carlos.