How to measure ISO

In article ,
Sandman wrote:

The one thing to remember with the old handheld incident lightmeter
is, you are going to get pure unadulterated exposure timing
information based on the ASA/DIN/ISO set and the f/number set. It
didn't care what camera you were carrying, or what lens you had
mounted.

Of course not, since it concerned exposure, not film sensitivity.

nope. iso is a measure of film sensitivity and now sensor sensitivity.

the fact that a handheld exposure meter can be used to determine
exposure for cameras with different size sensors and different format
film, all producing the same photos, proves what you're saying is
*wrong*.

it's as simple as that.

Back in the day - a 120 film with ISO 400 was a lot less grainier than a 135
film with ISO 400, for the same reasons. But back then, those weren't ISO
values one compared to each other than in exposure. These days, cameras and
sensor formats are a mess, so the values are used interchangeably but mean
something very different depending on your camera.

nonsense!

wow. that's some really ****ed up thinking.

In article ,
Sandman wrote:

Sandman:
With less total amount of light, the signal to noise ratio differs
between sensor sizes, meaning that ISO 200 on MFT has the same
s/n ratio as ISO 800 on FF.

Actually it depends on the pixel size, not the total area of the
sensor.

Not at all, a MFT 16mp camera and a MFT 24mp camera will have differing
quality
when compared 100x100 pixels to each other, due to pixel density, but the
photo
as a whole won't look any different, because even though the denser image is
more
noisier, it blends together in a 1x1 inch area when viewed on a screen or a
print.

now you're comparing different sensor resolutions?

you're all over the map.

A 16MP FF camera and a 16MP MFT camera, shot with the same settings at the
same
ISO 400 will yield a much grainier image from the MFT camera, because its
"equivalent" ISO 400 is a lot more sensitive than the FF cameras ISO 400.
I.e.
the smaller sensor needs to crank up it's light gathering capacity higher to
gather the same amount of light that the larger sensor gets.

you're confusing equivalency with exposure.

In article ,
Sandman wrote:

Sandman:
Higher sensitivity means it is able to gather more light. A ISO
400 film can gather more light than a ISO 100 film in the same
conditions. This is the very function of ISO - to determine how
much light a given film can gather per square inch/cm given a
specific exposure.

Sensitivity = output / input

In other words with the same aperture and exposure time, at a higher
ISO (=sensitivity) you will get a brighter image (i.e. stronger
output).

Correct.

that contradicts what you said elsewhere.

The sensitivity is the amplification of the signal of the image
sensor.

Indeed, which is how "ISO" is "emulated" by digital cameras, by adjusting the
EI
(Exposure Index) to roughly translate into a comparable ISO rating.

iso is not emulated.

it's measured, but unfortunately, the standard provides for more than
one way to do that.

But "ISO", the outdated value it is emulating, is a measure of a film's
capacity
to gather light in a given physical area. Not total area for the total slide,
but
amount of light gathered one a square inch.

nope. iso is a measure of the sensor's sensitivity to produce a given
response.

Since all 135 film is the exact
same
size, there is no need to measure it in any other way. A 135 film with ISO
400
from Fuji will have the same sensitivity as a 135 film with ISO 400 from
Kodak
since the value corresponds equally to both films since they are the same
size.

that contradicts what you said elsewhere.

you're so confused that you can't even keep track of what you say and
too pig-headed to admit your mistakes.

What it will not is correspond in graininess to 120-film of ISO 400. An
120-film
with ISO 400 will yield a similar exposure, but will be far less grainy since
it
will gather a *lot* more *total light* in the entire slide.

nonsense.

the same film is going to have the same grain patterns, regardless of
its size.

Back in the day, this wasn't a problem since no one compared graininess
between
120 and 135-film and ISO was a way to compare exposure only.
These days,
comparable cameras (i.e. handheld SLR to compact) come in a large variety of
sensor sizes, so the ISO rating as a way to compare noise loses its value.

nonsense.

In article ,
Sandman wrote:

See
https://photographylife.com/what-is-iso-in-photography "In
very basic terms, ISO is the level of sensitivity of your
camera to available light."

Sandman:
Higher sensitivity means it can gather more light.

Eric Stevens:
Higher sensitivity means it doesn't have to gather so much
light.

Sandman:
Incorrect.

Higher sensitivity means it is able to gather more light. A ISO
400 film can gather more light than a ISO 100 film in the same
conditions. This is the very function of ISO - to determine how
much light a given film can gather per square inch/cm given a
specific exposure.

It might gather more light under certain of low light but gathering
stops once the film is saturated. A high ISO film saturates more
easily and hence can be used with shorter exposures.

Uh yeah? That's the point.

you're contradicting yourself again.

In article ,
Whisky-dave wrote:

and the monkey doesn't own the copyright to any photos.

Except in Europe.

what does europe have to do with it? the photo wasn't taken in
europe
nor is it being litigated in europe.

however, it's hilarious.

I guess that is more of a PETA and Wiki-commons issue.

it's a peta issue, who is 'representing' the monkey.

it's nothing more than a publicity stunt which exploits the monkey, the
very opposite of what they claim to represent.

Not sure how it's exploits the monkey, I doubt the money even knows.

because it doesn't know it's being used for a publicity stunt.

then it's not beng exploited then is it.

of course it is.

the fact that it didn't consent means it's being exploited.

In article ,
Whisky-dave wrote:

nospam:
sensitivity determines how much light *needs* to be collected
for a given exposure.

Sandman:
Incorrect. ISO-sensitivity is a function of the film, it
determines how much light it can gather in a given square inch or
square cm. The ISO rating is for the film, not for the
"exposure".

this isn't about film.

ISO was invented for film, which is why it is outdated.

iso is not outdated.

there *must* be a way to measure the sensitivity of a sensor.

fortunately, there is and it is called iso.

No that was set up in the days of film it was then called ASA.

another one of your stupid pointless arguments.

Europe or rather gernamy had their DIN standard.
Later on rather than have a European standard from germany and an american
standard from america it was decided that an international standard ISO
but they used the ASA as their ruler and ASA 100 was then ISO 100 as that was
teh easist and most conviient method.

in other words, iso.

Back when ISO was created, all film was the same size, so a Fujifilm 100
and
a
Fujifilm 400 could be measured against each other since a square inch of
each
was a comparable part of the whole surface area. This was also the reason
why
ISO never could be compared between 135 and 120-film of course.

nonsense.

Well I agree with that, film size had nothing to do with ISO ASA or DIN.

ok.

now go tell sandman he's wrong.

film ranged in size from what went into tiny spy cameras all the way up
to large format sheet film and they all had the same iso for a given
film type.

at that time ISO didn't exist at least for the masses.

yes it did.

For most purposes ISO is pretty much the same as ASA was used.

it is the same.

In article ,
Whisky-dave wrote:


The sensitivity is the amplification of the signal of the image sensor.

Normally sensativity has nothing to do with amplification which is a
differnt thing entirely.

a sensor has a native iso.

higher isos than native are done by amplification, up to a point at
which it's done mathematically.

A person can be sensative to touch light or emotions. Sensitivity is just the
reaction to a given input.

whoosh.

In article ,
Whisky-dave wrote:


Soon yuo will be able to have a camera with NO moving parts, not even the
shutter release will move.

where 'soon' was roughly a decade ago.

yes I have one 256X384 pixels I was refering to a more high end camera
that people in this NG might consider buying.

the original iphone in 2007 had a 2 megapixel camera with no moving
parts, including the shutter release which was via a touch screen.

its successor, the iphone 3g in 2008, had a 3 megapixel camera, also
with no moving parts.

there may have been others before those, but the iphone is certainly
one of the most well known examples.

In article ,
Sandman wrote:

this isn't about film.

Sandman:
ISO was invented for film, which is why it is outdated.

iso is not outdated.

Incorrect.

there *must* be a way to measure the sensitivity of a sensor.

Correct.

fortunately, there is and it is called iso.

Which is outdated.

it's not outdated, nor have you offered any type of replacement.

worse, you keep contradicting yourself.

nospam:
you're so very confused.

Sandman:
Stop talking to yourself and posting it to usenet.

nospam:
**** off and die.

Sandman:
This is the level of "discussion" you're capable of. Only hot air
and being an asshole.

you're the one that threw the first punch. if you act like an
immature child, you'll be treated like an immature child.

I'm the one posting facts, you're the one throwing a tantrum in between all
your hot air and nothing comebacks.

you haven't been posting facts.

when you tell someone to stop posting to usenet, you are going to get a
nasty response in return.

if you keep it up, the responses will grow even nastier.

you are incapable of a rational discussion.

Most ironic thing you ever wrote.

snip

Run away, it's what you do best.

i don't run away.

i have more important things to do than argue with ignorant ****tards
who offer nothing more than one line responses, such as:
Incorrect.

as the saying goes,
Don¹t argue with idiots because they will drag you down to their
level and then beat you with experience.


Sandman:
Back when ISO was created, all film was the same size, so a
Fujifilm 100 and a Fujifilm 400 could be measured against each
other since a square inch of each was a comparable part of the
whole surface area. This was also the reason why ISO never could
be compared between 135 and 120-film of course.

nonsense.

Incorrect.

you're contradicting yourself again.

you said:
If you used small format film back then, ISO was comparable regardless of
what
camera you used.


film ranged in size from what went into tiny spy cameras all the way
up to large format sheet film and they all had the same iso for a
given film type.

Missing the point, as always. For the same *type* of camera, ISO was
comparable. These days, there are DSRL's, compacts and in-between formats,
that
between themselves have different formats.

it's comparable among any camera. that's why it's a standard.

If you used small format film back then, ISO was comparable regardless of
what
camera you used. These days, this is not the case.

you're contradicting yourself again.

you said:
This was also the reason why ISO never could
be compared between 135 and 120-film of course.


Sandman:
These days, ISO is out the window since the "film" (sensors) are
of different sizes, much like 135 and 120 back in the day. So ISO
as a value is irrelevant. ISO 400 on a FF and a MFT will yield
different sensitivities (i.e. graininess) and different end
result.

To match the end result, the ISO value need to be adjusted to the
crop factor squared.

you're confusing two different things, exposure and equivalency.

Incorrect. You may be, but I am not.

other way around.

snip irrelevancy

snipped only because it proves you wrong.

as you say,
Run away, it's what you do best.


however, for the same image *quality* (same noise, depth of field,
etc.), you would need to adjust iso *and* exposure for crop factor.

I.e. like I've said all along. It's like your reading comprehension is on a
three day delay.

you're confusing equivalency with exposure and your'e too pig-headed to
admit your confusion.

In article ,
Sandman wrote:

Sandman:
ISO was invented for film, which is why it is outdated.

It's also been adapted to digital. See
https://en.wikipedia.org/wiki/Film_speed#Digital

Not adapted, adopted. ISO is till being used to closely resemble what the
official ISO rating was for film, but it's still arbitrarily chosen by the
manufacturer.

it's not arbitrary.

Sure, most choose an ISO "equivalence" that adheres to a normal
range that is applicable across other manufacturers, but the ISO rating
doesn't
adhere to the "real" ISO standard.

nonsense. of course it does.

the problem is that the iso standard provides for more than one way to
measure it, so some camera makers cheat and use the way that results in
the biggest numbers.

it's a dumb standard but it's still a standard.

The new ISO standard for digital cameras
gives
manufacturers a lot of leeway in how it is measured and applied,

you're contradicting yourself again. first you say it's arbitrary, then
you say there's a standard. you can't have it both ways.

and as I've
said
- ISO 1000 on a MFT is *NOT* the same sensor sensitivity as ISO 1000 on a FF
camera.

wrong. it's exactly the same, which a handheld meter easily proves.

It will be roughly four times as grainy since MFT has less total
light to
make an image of.

grain is not the issue. you're moving the goalposts again.

This is why MFT should be set to ISO 250 to match ISO 1000
on a
FF camera.

Crop factor squared.

nonsense.

take an mft and ff camera, set both to iso 250, then set a handheld
exposure meter to iso 250 and meter a scene and take photos based on
what it shows.

they'll both be properly exposed.

tl;dr you're wrong.