When Electronic shutter "open"/"close"?

Strong light makes some people wink or blink. What I don't understand is how
the camera can capture this reaction considering it still takes a moment for
the motor nerves to respond to the stimuli. Nerve messages only travel about
35 miles an hour. One would think that by the time you see the flash it
actually reached you a moment before you realized it and the shutter opened
an closed prior to your blinking. No?


mark_

"mark_digital©" wrote in message
...
Strong light makes some people wink or blink. What I don't understand is
how the camera can capture this reaction considering it still takes a
moment for the motor nerves to respond to the stimuli. Nerve messages only
travel about 35 miles an hour. One would think that by the time you see
the flash it actually reached you a moment before you realized it and the
shutter opened an closed prior to your blinking. No?


mark_
The auto exposure uses a pre-flash on p&s models.
Dave Cohen

"mark_digital©" wrote in message
...
Strong light makes some people wink or blink. What I don't understand is
how the camera can capture this reaction considering it still takes a
moment for the motor nerves to respond to the stimuli. Nerve messages only
travel about 35 miles an hour. One would think that by the time you see
the flash it actually reached you a moment before you realized it and the
shutter opened an closed prior to your blinking. No?


mark_


Hi.

Like so many other things in Photography, don't bother about why it happens,
it just does. It is more important to learn how to get round it.

It did so well before Digital Cameras or Flashguns with Pre-flashes,
(whether for Red Eye or Exposure).

If you are working, one to one, with someone who is prone to the "Blinking"
problem, get them to tightly close their eyes, then just as you are about to
fire the shutter, ask them to open their eyes.

You should be able to get a photo, with eyes.

Roy G

"Tesco News" wrote in message
...
"mark_digital©" wrote in message
...
Strong light makes some people wink or blink. What I don't understand is
how the camera can capture this reaction considering it still takes a
moment for the motor nerves to respond to the stimuli. Nerve messages
only travel about 35 miles an hour. One would think that by the time you
see the flash it actually reached you a moment before you realized it and
the shutter opened an closed prior to your blinking. No?


mark_


Hi.

Like so many other things in Photography, don't bother about why it
happens, it just does. It is more important to learn how to get round it.

It did so well before Digital Cameras or Flashguns with Pre-flashes,
(whether for Red Eye or Exposure).

If you are working, one to one, with someone who is prone to the
"Blinking" problem, get them to tightly close their eyes, then just as you
are about to fire the shutter, ask them to open their eyes.

You should be able to get a photo, with eyes.

Roy G



You mean REAL TIGHT, like so tight it takes a moment to focus after you open
your eyes? Sounds like it might work.

Lots of people, when taking a photo, outloud count down (or up)
"3...2...1... click" That gives many subjects the verbal cue to
unconsciously blink...Really! If you shoot a little bit early or you
delay a bit, in an unpredictable manner, your subject will not be able
to anticipate the actual firing and you have a lowered probability of
catching them in the blinking.

In group photos I prefer to have my camera on tripod perfectly
pre-framed, then take the remote in my hand which is kind of down by my
side and less clearly visible to subjects, then standing next to my
camera I am looking directly at the group and giving some directions,
and I will often trigger the camera without verbal warning! If the
flash has a battery pack which provides very rapid recycling, I often
will shot TWO shots one right after the other, because often the
subjects relax a moment after the first shot is taken and you have much
less 'put on' expressions!

"mark_digital©" wrote in message
...

"Tesco News" wrote in message
...
"mark_digital©" wrote in message
...
Strong light makes some people wink or blink. What I don't understand is
how the camera can capture this reaction considering it still takes a
moment for the motor nerves to respond to the stimuli. Nerve messages
only travel about 35 miles an hour. One would think that by the time you
see the flash it actually reached you a moment before you realized it
and the shutter opened an closed prior to your blinking. No?


mark_


Hi.

Like so many other things in Photography, don't bother about why it
happens, it just does. It is more important to learn how to get round it.

It did so well before Digital Cameras or Flashguns with Pre-flashes,
(whether for Red Eye or Exposure).

If you are working, one to one, with someone who is prone to the
"Blinking" problem, get them to tightly close their eyes, then just as
you are about to fire the shutter, ask them to open their eyes.

You should be able to get a photo, with eyes.

Roy G



You mean REAL TIGHT, like so tight it takes a moment to focus after you
open your eyes? Sounds like it might work.

Hi.

Yes I do, and keep them closed for a few minutes.

When open, it is not so much the lack of focus, it has more to do with the
muscles being in a relaxed state after having been tensed up for a while.

Having said that, given some time, a "Blinker" will gradually stop being
nervous about the impending flash, and will be able to control their eyes
much better.

When shooting a portrait sesssion with Film, I never used to expect there to
be any good pictures in the first 36, if the subject was a "Blinker".

Roy G

"mark_digital©" wrote in message
...
Strong light makes some people wink or blink. What I don't understand is
how the camera can capture this reaction considering it still takes a
moment for the motor nerves to respond to the stimuli. Nerve messages only
travel about 35 miles an hour. One would think that by the time you see
the flash it actually reached you a moment before you realized it and the
shutter opened an closed prior to your blinking. No?


mark_

I am a bit curious as to where you got your data on the nerve responses
traveling at 35 mph??? (I don't know what the real number is, but would
expect it to be much higher because: 1) it is an involuntary response; and,
2) electrical signals (which a nerve signal is) travels at the speed of
light when in a vacuum...obviously, it would be slower in your body, how
much slower I haven't a clue.) But, even at 35 mph that is 51.33 fps and
how far does it have to travel from eye to brain? Six inches? That'd be
around 9.74 ms assuming your number is right and my guess on how far is
right...this would imply that with shutter speeds faster than 1/100 sec you
wouldn't have the problem...but we know that isn't right (from experience),
so I think you're a bit low on nerve impulse speed.

"george" writes:

"mark_digital©" wrote in message
...
Strong light makes some people wink or blink. What I don't understand is
how the camera can capture this reaction considering it still takes a
moment for the motor nerves to respond to the stimuli. Nerve messages only
travel about 35 miles an hour. One would think that by the time you see
the flash it actually reached you a moment before you realized it and the
shutter opened an closed prior to your blinking. No?


mark_

I am a bit curious as to where you got your data on the nerve responses
traveling at 35 mph??? (I don't know what the real number is, but would
expect it to be much higher because: 1) it is an involuntary response; and,
2) electrical signals (which a nerve signal is) travels at the speed of
light when in a vacuum...

Umm.. electrical signals don't travel at all in a vacuum. In a good
conductor, like copper or silver, they travel at about 95% of the
speed of light.

obviously, it would be slower in your body, how much slower I
haven't a clue.)

Quite a bit slower, actually, but I don't have any exact numbers.

But, even at 35 mph that is 51.33 fps and how far does it have to
travel from eye to brain? Six inches? That'd be around 9.74 ms
assuming your number is right and my guess on how far is
right...this would imply that with shutter speeds faster than 1/100
sec you wouldn't have the problem...but we know that isn't right
(from experience), so I think you're a bit low on nerve impulse
speed.

It's the preflash that triggers the blink, so the your calculations
don't mean a lot without knowing the time between preflash and
exposure.

--
Måns Rullgård

Måns Rullgård wrote:

It's the preflash that triggers the blink, so the your calculations
don't mean a lot without knowing the time between preflash and
exposure.


Nice concept, but the phenom has been around longer than flashes
utilizing preflash. And what's your source?

--
John McWilliams

george wrote:
"mark_digital©" wrote in message
...
Strong light makes some people wink or blink. What I don't understand is
how the camera can capture this reaction considering it still takes a
moment for the motor nerves to respond to the stimuli. Nerve messages only
travel about 35 miles an hour. One would think that by the time you see
the flash it actually reached you a moment before you realized it and the
shutter opened an closed prior to your blinking. No?


mark_

I am a bit curious as to where you got your data on the nerve responses
traveling at 35 mph??? (I don't know what the real number is, but would
expect it to be much higher because: 1) it is an involuntary response; and,
2) electrical signals (which a nerve signal is) travels at the speed of
light when in a vacuum...obviously, it would be slower in your body, how
much slower I haven't a clue.) But, even at 35 mph that is 51.33 fps and
how far does it have to travel from eye to brain? Six inches? That'd be
around 9.74 ms assuming your number is right and my guess on how far is
right...this would imply that with shutter speeds faster than 1/100 sec you
wouldn't have the problem...but we know that isn't right (from experience),
so I think you're a bit low on nerve impulse speed.

if there were one big nerve cell that did the whole job.
however, there are nerve to nerve junctions
which are chemical in nature,
and do not happen at the speed of light.