On 2018-08-01 11:11, Whisky-dave wrote:
On Monday, 30 July 2018 13:48:09 UTC+1, Carlos E.R. wrote:
On 2018-07-29 22:01, 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 shooting slower. The mirror has to be moved, takes time.

so does flushing the sensor prior to the photo and then tripping the
shutter, usually using a mechanical shutter. electronic shutters may
work in some cases but can have all sorts of problems in others.

pro sports photographers, who can use whatever camera they want, choose
slrs because it's faster than mirrorless.

https://www.adorama.com/alc/wp-conte...utterstock_152
803373-2.jpg
https://fotoblog.hu/wp-content/uploads/2016/08/587168650.jpg

nothing is perfect in every situation.

Sure. I simply know that my camera takes some time to think and then
shoot,

It doesn't think it's capturing data. A bit like a studetn taking down results of an experiment.

No, no. It is not capturing data before the mirror moves. I push the
button hard, it "thinks", then the mirror moves (or not) and takes the
photo.


even using the eyepiece, and using the "sports" configuration. It
is not that fast. My old chemical camera was faster (an SLR).

your old chemical camera wasn't recording any data, not until after you press the release.

It was doing the same basic thing: focusing, before the mirror moves.
The sensor is behind the mirror, there is no data collection and
processing before it moves in a DSLR.


I'm sure that fast cameras for sports can be designed without mirror,

Yes but they aren't SLRs or DLSRs (which have advantages) a pin hole camera does not have a mirror and it will act faster than a mirrorless camera too.

if
the delay is in switching the sensor mode.

The biggest delay in the currnet SLRs DSLRs is the time it takes the mirror to flip up and get it out of the way of the light path to the image sensor.
This is a mechanical movement with cogs and gears or other mechanical marvels in order to achieve what it's meant to do.

Well, that is precisely what I said.



Years ago the future was a semi-silvered mirror where the light would pass throught it so the mirror wouldn't, need to be moved.
But this has been superceeded in the most part by just having a sensor and the viewfinder turned into a screen a bit like watching TV there;s a delay even with live TV, I've noticed nearly a 1/2 second delay between the SD and HD channels of my TV although this is as much to do with syncing the sound.

And with having several different machines handling the video stream.
Each one adds a tiny delay.


--
Cheers, Carlos.