How to measure ISO

On Wed, 04 Nov 2015 14:25:32 -0500, nospam
wrote:

In article , Eric Stevens
wrote:

a stop is a unit of exposure. one stop more exposure is twice as much
light. that can be a larger f/stop on the lens, a slower shutter speed
or an increase in iso.

There are no standards for 'stops'.

yes there is. one stop more exposure is twice the amount of light.

One stop is the minimum number you need to play a tune on a pipe
organ.

Otherwise the use of the term is merely slang for 'exposure value'.

f/... stops are a different matter.

yes. that's the whole point.

exposure meters are also measured in stops. i have one that's about a
half-stop off.

I bet that's f/... stops.

you'll lose.

You mean your exposure meter is not calibrated in f/... stops? How on
earth do you set the diaphragm on your lens?
--

Regards,

Eric Stevens

On Wed, 4 Nov 2015 21:12:12 +0100, Alfred Molon
wrote:

In article , Alan Browne
says...
That said, I'd rather underexpose by half a stop
than overexpose by a stop.

Well, there is a general recommendation to expose to the right, to
minimise noise (also taking into account that cameras nowadays tolerate
some overexposure).

As a general rule, I would also expose to the left. The D750 gives me
little trouble with noise and I tend to have more trouble with burned
out highs than I do with loss of detail in the shadows.
--

Regards,

Eric Stevens

In article , Eric Stevens
wrote:

a stop is a unit of exposure. one stop more exposure is twice as much
light. that can be a larger f/stop on the lens, a slower shutter speed
or an increase in iso.

There are no standards for 'stops'.

yes there is. one stop more exposure is twice the amount of light.

One stop is the minimum number you need to play a tune on a pipe
organ.

not a very good tune.

Otherwise the use of the term is merely slang for 'exposure value'.

actually no. exposure value is a defined scale with one stop increments.

https://en.wikipedia.org/wiki/Exposu...icator_of_came
ra_settings

f/... stops are a different matter.

yes. that's the whole point.

exposure meters are also measured in stops. i have one that's about a
half-stop off.

I bet that's f/... stops.

you'll lose.

You mean your exposure meter is not calibrated in f/... stops?

correct.

it is calibrated in stops, although mine is a little out of calibration.

How on
earth do you set the diaphragm on your lens?

same as usual, with the front control wheel.

however, that has nothing to do with an exposure meter.

In article , Eric Stevens
wrote:

That said, I'd rather underexpose by half a stop
than overexpose by a stop.

Well, there is a general recommendation to expose to the right, to
minimise noise (also taking into account that cameras nowadays tolerate
some overexposure).

As a general rule, I would also expose to the left. The D750 gives me
little trouble with noise and I tend to have more trouble with burned
out highs than I do with loss of detail in the shadows.

ideally, it's best to expose to the right without clipping any
highlights.

On Wed, 04 Nov 2015 22:59:42 -0500, nospam
wrote:

In article , Eric Stevens
wrote:

That said, I'd rather underexpose by half a stop
than overexpose by a stop.

Well, there is a general recommendation to expose to the right, to
minimise noise (also taking into account that cameras nowadays tolerate
some overexposure).

As a general rule, I would also expose to the left. The D750 gives me
little trouble with noise and I tend to have more trouble with burned
out highs than I do with loss of detail in the shadows.

ideally, it's best to expose to the right without clipping any
highlights.

Why?

What do you do if, as I said, your problem *is* clipping highlights?
--

Regards,

Eric Stevens

In article , Eric Stevens
wrote:

As a general rule, I would also expose to the left. The D750 gives me
little trouble with noise and I tend to have more trouble with burned
out highs than I do with loss of detail in the shadows.

ideally, it's best to expose to the right without clipping any
highlights.

Why?

What do you do if, as I said, your problem *is* clipping highlights?

then reduce the exposure. if you clip the highlights, they're gone. you
don't want to clip highlights.

On Wed, 04 Nov 2015 22:59:42 -0500, nospam
wrote:

In article , Eric Stevens
wrote:

a stop is a unit of exposure. one stop more exposure is twice as much
light. that can be a larger f/stop on the lens, a slower shutter speed
or an increase in iso.

There are no standards for 'stops'.

yes there is. one stop more exposure is twice the amount of light.

One stop is the minimum number you need to play a tune on a pipe
organ.

not a very good tune.

Even with one stop, all you need is several octaves.

Otherwise the use of the term is merely slang for 'exposure value'.

actually no. exposure value is a defined scale with one stop increments

https://en.wikipedia.org/wiki/Exposu...icator_of_came
ra_settings

f/... stops are a different matter.

yes. that's the whole point.

exposure meters are also measured in stops. i have one that's about a
half-stop off.

I bet that's f/... stops.

you'll lose.

You mean your exposure meter is not calibrated in f/... stops?

correct.

it is calibrated in stops, although mine is a little out of calibration.

How on
earth do you set the diaphragm on your lens?

same as usual, with the front control wheel.

however, that has nothing to do with an exposure meter.

That will be news to many.
--

Regards,

Eric Stevens

In article , Eric Stevens
wrote:

How on
earth do you set the diaphragm on your lens?

same as usual, with the front control wheel.

however, that has nothing to do with an exposure meter.

That will be news to many.

learning is a good thing.

In article ,
Whisky-dave wrote:


yuo can test things yuorself.

http://photo.net/large-format-photography-forum/00Uajj

refering to a D700
" I just tried this on my "new" Schneider Symar 135mm f/5.6 and found it
was
dead on at all shutter speeds except 1/500 sec. which is actually
exposing at
1/400 sec. "

it's highly unlikely that a mechanical shutter would be accurate at all
shutter speeds except for just one, especially an old one.

irrelivant.

no

If it's out it's out. It could be the eclectical side that is out.

there is no electrical side. it's a mechanical shutter.

his test methodology is flawed.

Of course some people believe that the word digital means perfect in that
whatever shutter speed you set will be exact.

while nothing is perfect, they are correct.

electronic shutters (on both film and digital cameras) are *far* more
accurate than mechanical shutters ever will be.

yes they are but so what doesn't mean they'll never go wrong,
and how do you think they work then.

it's way the hell better than a mechanical shutter, that's for sure.

when's the last time you've seen a mechanical shutter rated at 400k
actuations? good luck if it isn't out of calibration after 1/10th that.

In article ,
Whisky-dave wrote:


Of course some people believe that the word digital means perfect in
that
whatever shutter speed you set will be exact.

while nothing is perfect, they are correct.

electronic shutters (on both film and digital cameras) are *far* more
accurate than mechanical shutters ever will be.

yes they are but so what doesn't mean they'll never go wrong,
and how do you think they work then.

it's way the hell better than a mechanical shutter, that's for sure.

I thought you said the D700 was a mechanical shutter.

it does not, nor have just about all slrs since the 1980s or so.

when's the last time you've seen a mechanical shutter rated at 400k
actuations? good luck if it isn't out of calibration after 1/10th that.

what has 400k got do do with anything.

it demonstrates the reliability of electronic shutters.

you'll never find a mechanical shutter that will last anywhere near
that long without going out of calibration, assuming it still works.

YOU've really got NO idea have you.

far more than you do

You've already claimed that one shutter speed can't be out when the rest aren't.

that's correct.