ISO is not real In Digital Camra's

[Soocom1]

Right, they are not comparable.


Actually I meant to say compatible, but the spell check hit me.

but I digress

 

[petrochemist]

LMAO i'm not wrong, yeah camera's have a setting called ISO but it's not what the real ISO is like in Film Camera..
And it's not what people think it is in digital camera, and IT"S NOT part of the exposure triangle at all.
If the ISO (applied gain) is applied after the shot is taken, then it's not part of the exposure triangle.

Let me see there's
ISO 12232 Speed rating for digital cameras (I believe it has 5 alternative procedures in it)
ISO 6 Speed rating for B&W negative film
ISO 2240 Speed rating for colour slide film
ISO 5800 Speed rating for colour print film
ISO 7187 Speed rating for direct positive colour print film
ISO 9378 Speed rating for vesicular microfilm

Yet somehow the digital version is 'not real' & all the others are?

 

[Derrel]

This thread!! So much winning!

 

[VidThreeNorth]

Actually, we covered most of the this topic just a while back:

"Digital Photography ISO"
"Digital Photography ISO"

 

[Derrel]

Actually, we covered most of the this topic just a while back:

"Digital Photography ISO"
"Digital Photography ISO"

A link from a 2009 article found in one of the above articles:

Behind the scenes: extended highlights!

 

[Grandpa Ron]

Wow six pages of serious discussion over what is basically opinion. Next we can start on "How many angels can dance on the head of a pin". That has only been debated since the middle-ages.

That fact is with film, if I increase the ISO (ASA to us old folks), the exposure increases. With digital, if I increase the ISO, the exposure increases. How it was done chemically with film and how it is done electronically with digital does not make any difference.

The end result, with film and digital, is the higher ISO more exposure. The methodology is a moot point.

 

[dunfly]

I had a philosophy professor in college that said that most controversies are a matter of semantics. In this case, it is the word "exposure". Technically "exposure" is the amount of light that hits a surface, whether it is film or a sensor. Based on that definition ASA or ISO is irrelevant to exposure. But when we talk about the exposure triangle, we are also including what the camera does with the light, either chemically with film or digitally with digital. In this case, we are talking about the finished product, either the image that is recorded by the film or the image that is saved to the SD (or whatever) card. So it looks like we have 6 pages of discussion because someone is trying to apply the technical definition of exposure to the general term exposure triangle, which almost everyone understands includes what the camera does with the light, i.e. ASA or ISO.

 

[markjwyatt]

...Technically "exposure" is the amount of light that hits a surface, whether it is film or a sensor. Based on that definition ASA or ISO is irrelevant to exposure. But when we talk about the exposure triangle, we are also including what the camera does with the light, either chemically with film or digitally with digital...

I don't want to make drag this on too much longer, but I think exposure has to be the amount of light absorbed by the photosensitive medium AND its effect on the medium. In film you would say the average number of latent image sites (of average size) transformed per area due to the flux (controlled by the lens and aperture) and integration time (controlled by the shutter) as well as the sensitivity of the sites (characterized by the ISO). If you take a film camera that is empty and click the shutter you have light hitting a surface, but no exposure, so exposure needs to involve the entire "exposure" triangle to have any meaning, philosophically speaking ( ).

 

[smoke665]

NO IT's not increasing voltage to the sensor, has nothing to do with ISO,
ISO is applied after the Image is taken.. NOT at the time the shot is taken, so voltage to the sensor has noting to do with ISO settings..
ISO is Applied Gain AFTER, I repeat AFTER the image is Taken..
the shot is taken from the sensor, to the Analog Gain, then to the AD converter, then ISO is applied as you see in the diagram..

So your wrong, and looks like YOUR your understanding is not fully correct at all..

First of all you've limited yourself to a very narrow view, completely ignoring the difference between analog and digital gain. Then you post a schematic that shows an analog amplifier receiving the signal from the sensor, but some how ignored it's contribution. Third you've pushed that ISO is nothing but applied gain, yet in your comment above you say "then ISO is applied", so if it's nothing but gain why do you claim it's applied? Finally you appear unwilling to accept that in 6 pages of comments no one has supported your position. I tried to support how you were arriving at some of you claims, only to be told I was wrong for agreeing that some or your points were true. This is one of those self feeding beasts that will dye down, come back and continue to clog the forum for years to come. I for one wish the powers above would create and UNFOLLOW button for threads so you can stop them from continuing to show up on the Active T0pics list.

 

[Designer]

.. as well as the sensitivity of the sites (characterized by the ISO).

Are you saying that a change to the ISO setting affects the sensitivity of the sensor?

 

[limr]

Wow six pages of "serious" discussion over what is basically opinion.

Fixed that for ya.

The methodology is a moot point.

 

[markjwyatt]

.. as well as the sensitivity of the sites (characterized by the ISO).

Are you saying that a change to the ISO setting affects the sensitivity of the sensor?

Effectively, I suspect. Perhaps I should have said "the sensitivity of the sites (characterized by the ISO)" and the system that process the sites... But then again, if we take the sensor as really a single sensitivity (ISO), the original statement may still be correct. Any effective change in ISO would then be due to processing.

 

[Ysarex]

It's fair to draw a line and say how some tool is implemented isn't important to you -- moot point. But if you're going to be using whatever that tool is that you don't care how it works (a camera in this case) do you understand enough so that you make appropriate usage choices? Or do you also not care about the outcomes you produce with that tool? Given this thread's topic, digital camera ISO, do you know what happens photographically when you adjust that setting?

I have a neighbor kid who's always looking for a couple extra bucks and comes around wanting to help in the garden for some cash. The other day he was here pestering me and I had some dead viburnum that had be be cut out so I gave him a hand saw and told him to cut as low to the ground as possible. Then I said I was going to do something else in the garage and would be back to check on him in a few minutes. When I got back he was bending over the viburnum trunks and using the saw to chop at them like it was a hatchet (bent some saw teeth, grrrrrr).

Reminded me of how some people I meet use their cameras.

Joe

 

[Ysarex]

.. as well as the sensitivity of the sites (characterized by the ISO).

Are you saying that a change to the ISO setting affects the sensitivity of the sensor?

Effectively, I suspect. Perhaps I should have said "the sensitivity of the sites (characterized by the ISO)" and the system that process the sites... But then again, if we take the sensor as really a single sensitivity (ISO), the original statement may still be correct. Any effective change in ISO would then be due to processing.

Back a page or so there's a lengthly post by TimC that contains considerable detail. One point he makes:

Digital sensors do not have adjustable sensitivity.

And he is completely correct.

Joe

 

[Designer]

..if we take the sensor as really a single sensitivity (ISO),

Thinking about how to make a sensor "variable" might include some kind of moveable/changeable shade of some sort positioned on/in front of the sensor such that when the ISO setting was changed, the shade would change accordingly.

Seems rather complicated.

Not only do I think it will never happen, but I see no need for it, either.