On 2018-08-01 11:34, Whisky-dave wrote:
On Monday, 30 July 2018 13:56:09 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 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.

except that a digital display is delayed versus pure optical.

it takes time to read the data off the sensor, process it and send it
to the display.

Surely less than 1/50 S (video speed).

yes far less, in micoseconds if not nanoseconds, per pixel or rather the smallest point on the sensor.
And dontl forget the mor epiuxels the longer it can take to 'transmit' the image from the sensor and convert it to a digital number.

Yes, of course.


the latency is shorter than it used to be and won't matter for still
life, but *will* matter for sports or other action photography as well
as very low light.

Well, for very low light the display could enhance the picture as if we
were using a night visor,

That's how my MILC a canon EOS M3 seems to work.


so that could be a definite improvement. I do
astrophotography, and finding the red moon on the eyepiece the other day
was impossible.

If you do astrophotography then yuo yuo really should understand how old you're photos really are, even if taking pictures of the moon you are seeing it as it was 1.25 seconds ago.
And No amount of clever electronics in a camera will change that.

LOL.

That has no importance at all. X-)

Anyway, such shots are measured in seconds, not fractions of seconds.
The result is an average of the light over a long period.






for example, try using a digital viewfinder in extremely low light.
either it blacks out because the light level is too low, the frame rate
drops to compensate or it amplifies what it can 'see' and the
viewfinder is too noisy to be of much use.

with an optical viewfinder, your eyes adjust.

As I wrote above, I was in exact this situation and my experience was
different.

All humans and most creatures on the planet have eyes that adjust to differnt light levels, if you're in the dark for a significant amount of time you're eyes can become very senative to light.

Yes, but not enough.


there is also no battery drain with an optical viewfinder (or heat).

Well, my camera lights up the display when using the viewfinder with the
settings instead of the scene. So, no gain.

What do yuo mean by no gain ?

That I already use my batteries fast. It is not much of a difference.



There is no quick button to
disable it.

I thought most camera you could blank the display, you just have to know how to do it.

In a menu.


It just times out and switches off, till I make a photo and
then displays it.

Most cameras have a setting for this delay I think mines set to 2 seconds.

Yep.



I simply carry two batteries. Sigh. I would need a charger for the car.

And you might need a charger for the car or a 'gas' station nearby.
LOL.

--
Cheers, Carlos.