How to measure ISO

In article ,
Sandman wrote:

Sandman:
ISO is expected brightness,

no it isn't.

iso is a measure of sensitivity.

Sensor sensitivity or "apparent sensitivity", since you want to distinguish
them?

only because you're fixated on amplification.

Sandman:
which means that the amplification (sensitivity) is different for
different sensors.

nobody but you cares what the amplification is and you have no way
of knowing how much there is unless you put the sensor on a test
bench and hook it up to lab instruments.

Amplification leads to noise, and more people than me care about noise.

they might care about noise, but they don't care about amplification,
full well capacity, pixel size, fill factor, quantum efficiency, a/d
converters, quantization errors or any other geek stuff.

what matters is the photos they get, and if the noise isn't noticeable
(which it normally isn't), then they don't care about that either.

With smaller photo sites, found in smaller sensors, each photo site receives
less
light and the signal needs to be amplified more while reporting the same ISO
value as a larger sensor.

smaller sensors *might* have smaller photosites.

you're also ignoring the sensor's qe and fill factor of the photosites.

More amplification leads to more noise, which is what makes people think
smaller
sensors are noisier, when in reality they aren't, they're just not receiving
as
much light.

you just said a smaller sensor needs more amplification, resulting in
more noise, which means smaller sensors are noisier.

now you say they really aren't.

make up your mind.

If you give them the same amount of total light (i.e. the same amount of
light
per photo site), the noise levels are comparable to that of a larger sensor,
while brightness is the same. But, you have to adjust the ISO value down by the
crop factor squared (roughly).

not quite, because the same amount of light on smaller photosites would
likely saturate them.

you're confusing that with equivalency, a separate topic. you also have
to adjust the focal length and f/stop to be truly equivalent.

In article ,
Sandman wrote:

Sandman:
Amplification is sensor sensitivity.

Amplification is NOT sensor sensitivity.

Please explain how the sensor gets more sensitive without amplifying the signal.

on the *same* sensor, it does.

you were comparing *different* sensors.

In article , Eric Stevens wrote:

Eric Stevens:
I assumed you were writing adult English.

The sensor is sensitive, or not, according to it's own native
characteristics. How much it is later amplified has nothing to
do with it's native sensitivity.

Sandman:
Ah, sematics.

"The branch of linguistics which deals with meaning". Yes. Meaning
is important. Otherwise it is just meaningless babel.

Indeed - semantic trolling is where the troll ignores the topic and the context
and starts dissecting the meaning of individual words and phrases.

Sandman:
Are you now claiming that one can not change the sensors
sensitivity?

Of course you can change it - by changing the sensor in some way.

So, you can change "the sensors" sensitivity by not using "the sensor"? YOu've
gone off the deep end. Pity, you really were holding up pretty good for a
while.

Sandman:
I mean, technically, I actually agree with that, but when people
change their ISO values, they also call that changing the sensors
sensitivity to light.

What actually happens is not affected by what people call it.

Since no one has talked about "what actually happens" up until your semantic
trolling, this is of course of no concern to me.

Sandman:
But ok, since you are just semantically trolling by now, I have to
be even more precise.:

FACT: Brightness is the result of captured light FACT: Smaller
sensors have smaller photo sites. FACT: Smaller photo sites
capture less light FACT: For a smaller sensor with smaller photo
sites to achieve the same brightness as a larger sensor with
larger photo sites, the signal needs to be amplified FACT:
Amplification leads to noise FACT: The level of amplification is
user-controlled by setting the ISO value

Your mistake is assuming brightness is determined by the quantity of
light.

Haha, classic wriggling. Eric is now claiming that it's wrong to assume that
the quantity of light determines brightness. Hilarious.

Well it is and it isn't. You have to qualify what you mean.

Not really, the statement is 100% factual as stated.

Brightness is determined by how full an individual photosite may be.
First, small photosites require less light to fill them. Second,
tere is no single level aginst which it can be determined whether a
photosite is filled. It all depends on the circumstances of the
particular photosite.

The factual statement above doesn't in any way mention whether or not a photo
site is "filled" or not. Whether or not a photo site is "filled" doesn't
determine whether or not the amount of light determines the level of
brightness.

Sandman:
With the facts, we can determine that if we were to give each
photo site in the smaller sensor the same amount of light as the
photo sites in the larger sensor, the amplification can be
comparable between the two, which means that the noise level will
be comparable. When doing this, we also need to adjust the sensor
amplification (ISO value) down on the smaller sensor.

This is where what you call 'semantics' becomes important. What
exactly do you call the same amount of light? How do you measure it?

With a given exposure, a MFT sensors receives (roughly) one fourth the amount
of light as a FF sensor. If you were to give the MFT sensor the same amount of
total light (I trust you are familiar with how to operate a camera to give a
sensor more light), the signal amplification will be comparable.

Simple physics.

--
Sandman

In article , nospam wrote:

Sandman:
FACT: Smaller sensors have smaller photo sites.

no.

the photosites *might* be smaller, but it's not always the case.
they might be the same size or even larger.

*if* the megapixel count is the same on both sensors, *then* the
photosites will be smaller on the smaller sensor. if it's different
the you have more variables in the mix.

This has already been supported by me:

http://jonaseklundh.se/files/cameras_since_2013.png

Sandman:
FACT: Smaller photo sites capture less light

true, but that's independent of sensor size.

Incorrect, given the fact that all contemporary cameras have smaller photo sites
if they have smaller sensors.

Sandman:
FACT: For a smaller sensor with smaller photo sites to achieve the
same brightness as a larger sensor with larger photo sites, the
signal needs to be amplified

no.

Note: no support for opposing view. Fact remains factual.

--
Sandman

In article , nospam wrote:

Sandman:
ISO is expected brightness,

nospam:
no it isn't.

iso is a measure of sensitivity.

Sandman:
Sensor sensitivity or "apparent sensitivity", since you want to
distinguish them?

only because you're fixated on amplification.

Why didn't you answer the question?

Sandman:
which means that the amplification (sensitivity) is
different for different sensors.

nospam:
nobody but you cares what the amplification is and you have no
way of knowing how much there is unless you put the sensor on a
test bench and hook it up to lab instruments.

Sandman:
Amplification leads to noise, and more people than me care about
noise.

they might care about noise, but they don't care about
amplification, full well capacity, pixel size, fill factor, quantum
efficiency, a/d converters, quantization errors or any other geek
stuff.

As I said - a lot of people care about noise, which is what amplification leads
to. Not sure what the babble above is supposed to say in this context.

what matters is the photos they get, and if the noise isn't
noticeable (which it normally isn't), then they don't care about
that either.

No one has talked about noise that isn't noticeable. I have been in reference
to noticeable noise all the time. It's funny how you have to add the "if"
qualifier to your statement.

Sandman:
With smaller photo sites, found in smaller sensors, each photo
site receives less light and the signal needs to be amplified
more while reporting the same ISO value as a larger sensor.

smaller sensors *might* have smaller photosites.

Smaller sensors have smaller photo sites:

http://jonaseklundh.se/files/cameras_since_2013.png

Sandman:
More amplification leads to more noise, which is what makes people
think smaller sensors are noisier, when in reality they aren't,
they're just not receiving as much light.

you just said a smaller sensor needs more amplification, resulting
in more noise, which means smaller sensors are noisier.

Indeed - since they are getting less light.

now you say they really aren't.

If they get the same amount of light.

make up your mind.

Learn to read.

Sandman:
If you give them the same amount of total light (i.e. the same
amount of light per photo site), the noise levels are comparable
to that of a larger sensor, while brightness is the same. But,
you have to adjust the ISO value down by the crop factor squared
(roughly).

not quite, because the same amount of light on smaller photosites
would likely saturate them.

Incorrect.

you're confusing that with equivalency, a separate topic. you also
have to adjust the focal length and f/stop to be truly equivalent.

All my claims have been with equal focal length and f/stop.

--
Sandman

In article , nospam wrote:

Sandman:
Amplification is sensor sensitivity.

Eric Stevens:
Amplification is NOT sensor sensitivity.

Sandman:
Please explain how the sensor gets more sensitive without
amplifying the signal.

on the *same* sensor, it does.

Not according to Eric. You have to replace the sensor in the camera to get a
different level of sensitivity. Yeah...

you were comparing *different* sensors.

Indeed.

--
Sandman

On 23 Nov 2015 06:43:38 GMT, Sandman wrote:

In article , Eric Stevens wrote:

Eric Stevens:
I assumed you were writing adult English.

The sensor is sensitive, or not, according to it's own native
characteristics. How much it is later amplified has nothing to
do with it's native sensitivity.

Sandman:
Ah, sematics.

"The branch of linguistics which deals with meaning". Yes. Meaning
is important. Otherwise it is just meaningless babel.

Indeed - semantic trolling is where the troll ignores the topic and the context
and starts dissecting the meaning of individual words and phrases.

Very interesting. I would be grateful if you could post me a reference
for that.

What's that? You don't have a reference?

Oh, I se: you just made it up. :-(

Sandman:
Are you now claiming that one can not change the sensors
sensitivity?

Of course you can change it - by changing the sensor in some way.

So, you can change "the sensors" sensitivity by not using "the sensor"? YOu've
gone off the deep end. Pity, you really were holding up pretty good for a
while.

Your problem is not just an imperfect knowledge of English. You just
can't think straiht.

Sandman:
I mean, technically, I actually agree with that, but when people
change their ISO values, they also call that changing the sensors
sensitivity to light.

What actually happens is not affected by what people call it.

Since no one has talked about "what actually happens" up until your semantic
trolling, this is of course of no concern to me.

Dear me. We haven't been talking about what actually happens. Well I
know you haven't but I have been trying to do so.

Sandman:
But ok, since you are just semantically trolling by now, I have to
be even more precise.:

FACT: Brightness is the result of captured light FACT: Smaller
sensors have smaller photo sites. FACT: Smaller photo sites
capture less light FACT: For a smaller sensor with smaller photo
sites to achieve the same brightness as a larger sensor with
larger photo sites, the signal needs to be amplified FACT:
Amplification leads to noise FACT: The level of amplification is
user-controlled by setting the ISO value

Your mistake is assuming brightness is determined by the quantity of
light.

Haha, classic wriggling. Eric is now claiming that it's wrong to assume that
the quantity of light determines brightness. Hilarious.

That's a good logical argument. Can you do any better?

Well it is and it isn't. You have to qualify what you mean.

Not really, the statement is 100% factual as stated.

Fuzzy as it may be.

Brightness is determined by how full an individual photosite may be.
First, small photosites require less light to fill them. Second,
tere is no single level aginst which it can be determined whether a
photosite is filled. It all depends on the circumstances of the
particular photosite.

The factual statement above doesn't in any way mention whether or not a photo
site is "filled" or not. Whether or not a photo site is "filled" doesn't
determine whether or not the amount of light determines the level of
brightness.

I really would like to know what *you* mean by "amount of light". It's
not a hard question - if you know what you are talking about.

Sandman:
With the facts, we can determine that if we were to give each
photo site in the smaller sensor the same amount of light as the
photo sites in the larger sensor, the amplification can be
comparable between the two, which means that the noise level will
be comparable. When doing this, we also need to adjust the sensor
amplification (ISO value) down on the smaller sensor.

This is where what you call 'semantics' becomes important. What
exactly do you call the same amount of light? How do you measure it?

With a given exposure, a MFT sensors receives (roughly) one fourth the amount
of light as a FF sensor. If you were to give the MFT sensor the same amount of
total light (I trust you are familiar with how to operate a camera to give a
sensor more light), the signal amplification will be comparable.

That's all very fine, but what are the units of measure to enable you
to define whether or not the same amount of light has been received?

Simple physics.

I would have thought so.
--

Regards,

Eric Stevens

On 23 Nov 2015 06:46:39 GMT, Sandman wrote:

In article , nospam wrote:

Sandman:
FACT: Smaller sensors have smaller photo sites.

no.

the photosites *might* be smaller, but it's not always the case.
they might be the same size or even larger.

*if* the megapixel count is the same on both sensors, *then* the
photosites will be smaller on the smaller sensor. if it's different
the you have more variables in the mix.

This has already been supported by me:

http://jonaseklundh.se/files/cameras_since_2013.png

Posting a list you have pinched from somewhere else without
explanation doesn't offer support for anything.

Sandman:
FACT: Smaller photo sites capture less light

true, but that's independent of sensor size.

Incorrect, given the fact that all contemporary cameras have smaller photo sites
if they have smaller sensors.

Are you trying to say that a contemporary camera which has smaller
photosites has a smaller sensor?

Sandman:
FACT: For a smaller sensor with smaller photo sites to achieve the
same brightness as a larger sensor with larger photo sites, the
signal needs to be amplified

no.

Note: no support for opposing view. Fact remains factual.

But it's not a fact.

What is the capacitance of the photosite?
--

Regards,

Eric Stevens

On 23 Nov 2015 06:53:32 GMT, Sandman wrote:

In article , nospam wrote:

Sandman:
ISO is expected brightness,

nospam:
no it isn't.

iso is a measure of sensitivity.

Sandman:
Sensor sensitivity or "apparent sensitivity", since you want to
distinguish them?

only because you're fixated on amplification.

Why didn't you answer the question?

Sandman:
which means that the amplification (sensitivity) is
different for different sensors.

nospam:
nobody but you cares what the amplification is and you have no
way of knowing how much there is unless you put the sensor on a
test bench and hook it up to lab instruments.

Sandman:
Amplification leads to noise, and more people than me care about
noise.

they might care about noise, but they don't care about
amplification, full well capacity, pixel size, fill factor, quantum
efficiency, a/d converters, quantization errors or any other geek
stuff.

As I said - a lot of people care about noise, which is what amplification leads
to. Not sure what the babble above is supposed to say in this context.

And there is the problem: you don't know what the terms mean.

what matters is the photos they get, and if the noise isn't
noticeable (which it normally isn't), then they don't care about
that either.

No one has talked about noise that isn't noticeable. I have been in reference
to noticeable noise all the time. It's funny how you have to add the "if"
qualifier to your statement.

It's because of your semantic uncertainty.

Sandman:
With smaller photo sites, found in smaller sensors, each photo
site receives less light and the signal needs to be amplified
more while reporting the same ISO value as a larger sensor.

smaller sensors *might* have smaller photosites.

Smaller sensors have smaller photo sites:

http://jonaseklundh.se/files/cameras_since_2013.png

Sandman:
More amplification leads to more noise, which is what makes people
think smaller sensors are noisier, when in reality they aren't,
they're just not receiving as much light.

you just said a smaller sensor needs more amplification, resulting
in more noise, which means smaller sensors are noisier.

Indeed - since they are getting less light.

now you say they really aren't.

If they get the same amount of light.

make up your mind.

Learn to read.

Sandman:
If you give them the same amount of total light (i.e. the same
amount of light per photo site), the noise levels are comparable
to that of a larger sensor, while brightness is the same. But,
you have to adjust the ISO value down by the crop factor squared
(roughly).

not quite, because the same amount of light on smaller photosites
would likely saturate them.

Incorrect.

He is correct. If you think we are wrong, please explain.

you're confusing that with equivalency, a separate topic. you also
have to adjust the focal length and f/stop to be truly equivalent.

All my claims have been with equal focal length and f/stop.
--

Regards,

Eric Stevens

On 23 Nov 2015 06:53:32 GMT, Sandman wrote:

All my claims have been with equal focal length and f/stop.

Shouldn't you have scaled the focal length according to the crop
factor?
--

Regards,

Eric Stevens