The ISO argument

[Braineack]

Then tell me if it does not effect exposure!

It doesn't.


What you're asking us to do is the equivalent of this:

I took your photo and lowered the ISO; this is the same image, same shutter speed and aperture.

Tell me ISO doesn't affect the exposure.

 

[Soocom1]

OK.. So one thing that I was NOT aware of, was that the "native ISO" from the manufacturers may be varied based on manufacturing techniques and materials. (This is akin to the diff. between iron base materials that are used for iron engines from Ford. v. Chevy.) Oh and please don't read too much into that, its simply a comparison that car guys will understand.

But they still do effectively the same thing.

BUT the "native ISO" is a measurement of the sensitivity of the sensor itself and using simple arguments here, if the "native ISO" of a particular camera is say equivalent to 100, then anything below that is akin to filling a bucket and letting the water keep running after it overflows. Your simply loosing the ability to collect and your gaining no advantage.
At least that's how I am reading this.

But this is also determined on the A/D converter and bit rate if I read that correctly.
So, that would mean to me (correct me if I am am wrong here) but if the bit rate was say 256, then an extended low and high ISO would show the same level of noise but the contrast would be substantially wider and moreover, total tonal range would also be more dynamic.

 

[Derrel]

Topic For Round II of "The ISO Argument": The "best" ISO to set on the ISO dial or LCD panel (with a modern d-slr) is usually not the lowest ISO, but rather is often 200, or 320, or 400, or 500, or 640.

Discuss/argue.

 

[Soocom1]

Topic For Round II of "The ISO Argument": The "best" ISO to set on the ISO dial or LCD panel (with a modern d-slr) is usually not the lowest ISO, but rather is often 200, or 320, or 400, or 500, or 640.

Discuss/argue.

I would say fine, but this also tends to lead to another question feeding off my previous post.
That is, would you USE a lower ISO if offered?
Don't worry about the technical side of things, if you had a 6 ISO setting on the camera would you use it?

 

[Derrel]

I have LONG advocated 320 to 400 as giving the widest "shooting envelope" for the majority of situations. I grew up on ASA 125 B&W, then 400 ASA b&W, then ISO 100 ro 200 color negative film, then ISO 25,64,and 100 color reversal films, etc. One of my earliest d-slrs was the Fuji S1 Pro, which had a lowest ISO of 320,and was a terrible daylight flash camera as a result. My feeling is that setting one's ISO at 50,64,80,100, 125,160 area leads to a lot of blurry images,in many situations.

For MOST daylight, hand-held use, I feel that low ISO levels, below 50 let's say, are of limited use. For studio flash use, low ISO values can be of some use, especially with older flash units which are not easily lowered to less than 100 or 200 Watt-seconds.

 

[Ysarex]

OK.. So one thing that I was NOT aware of, was that the "native ISO" from the manufacturers may be varied based on manufacturing techniques and materials. (This is akin to the diff. between iron base materials that are used for iron engines from Ford. v. Chevy.) Oh and please don't read too much into that, its simply a comparison that car guys will understand.

But they still do effectively the same thing.

BUT the "native ISO" is a measurement of the sensitivity of the sensor itself and using simple arguments here, if the "native ISO" of a particular camera is say equivalent to 100, then anything below that is akin to filling a bucket and letting the water keep running after it overflows. Your simply loosing the ability to collect and your gaining no advantage.
At least that's how I am reading this.

So not quite -- this was part of the misconception in the earlier thread a few weeks ago and likewise part of Tony Clickbait's misunderstanding in his recent video. Our camera sensors don't have ISO ratings. Base ISO is not the light sensitivity of the sensor. The ISO standard also explicitly states that the ISO ratings do not apply to raw files. The ISO standards (two different methods used by manufactures to establish the values: SOS or REI) identify a standard brightness level in a SOOC sRGB JPEG relative to the brightness of the scene. That's it and that's all.

The bucket analogy catching water is a good one and absolutely correct that once the bucket is full you stop recording information. The sensor does have a full well capacity and if we exceed that we clip highlights.

But this is also determined on the A/D converter and bit rate if I read that correctly.
So, that would mean to me (correct me if I am am wrong here) but if the bit rate was say 256, then an extended low and high ISO would show the same level of noise but the contrast would be substantially wider and moreover, total tonal range would also be more dynamic.

The same exposure shows the same noise regardless of ISO if we're talking about shot noise which we should be. ADC bit depth does not determine dynamic range it determines the how discreetly the data is recorded. Think of two sets of stairs both climbing a hill that is 50 feet high. 50 feet is the dynamic range. One set of stairs has 35 steps and the other has 60 steps -- that's the bit depth variation. Both stairs reach the top, DR, but one is smoother than the other.

Joe

 

[zombiesniper]

Are we really going to dig up the same old arguments and rage another war that WILL NOT MAKE ANYONE A BETTER PHOTOGRAPHER?

Seriously! If you wish to debate trivial facts that are won't make a darn bit of difference to an image please resurrect an old thread the rest of humanity has blocked.



NOBODY has ever won this argument. It's like pushing a rope. Fun to do for a bit but eventually you realize you're getting nowhere.

 

[Soocom1]

I personally had to take a break from the discussion because of the obtuse direction it was taking.

But it is worth the discussion because all too often, people do not grasp the specifics of a particular technology.

Its akin (yes another metaphor) to someone saying that you will go faster in a car with high octane or that we can eventually make a large truck that gets 100 mpg with gasoline.
Its superfluous in its base without regard to the technical aspects that make the system a discussion of the absurd if those speaking are working from a low level knowledge base.


i too am guilty of that but it also opens insight to something that may enhance one's knowledge base.

 

[zombiesniper]

My point is if both can get you to the finish line in a fashion that the difference is not discernible to the viewer..........who cares.

 

[Soocom1]

I think that there are some (including myself) who see the technical side as something that can be exploited if understood.

I get what your saying. In the end, the universe will go cold and we'll all be dead.
But for now, this moment, its relevant to those who see something worth pursuing and discussing.

 

[wfooshee]

Then tell me if it does not effect exposure!

It doesn't.


What you're asking us to do is the equivalent of this:

I took your photo and lowered the ISO; this is the same image, same shutter speed and aperture.

View attachment 171395

Tell me ISO doesn't affect the exposure.

I like this example. To reinforce the point (or beat the dead horse...) Braineack didn't change the amount of light that hit the sensor to produce the original image, so he did not change the exposure. He changed how that exposure was rendered. I think it's an easier point to grasp when you come from years of film, where the so-called "third variable" didn't exist. You exposed for the film you had loaded.

Changing the ISO is a bit artificial when you move from film to digital. It's like cheating, somehow. Let's "pretend" the camera is faster than it is, so we can shoot in this low light without needing 3 seconds of open shutter. Kind of like pushing film...

To the OP, exposure is light on the sensor. The only things that affect exposure are aperture and shutter speed. Adjusting the ISO without adjusting the others changes the rendering, not the exposure. You might call it semantics, but it's an important distinction. If the camera is in an auto-exposure mode, changing the ISO does change the exposure, but it does not change the rendering. You're interchanging expose with render.

 

[Ysarex]

I think that there are some (including myself) who see the technical side as something that can be exploited if understood.

YES!

Understanding how my camera works allows me to exploit that understanding to take better photos, and I do.

Joe

I get what your saying. In the end, the universe will go cold and we'll all be dead.
But for now, this moment, its relevant to those who see something worth pursuing and discussing.

 

[zombiesniper]

I fully understand....and applaud exploiting an aspect of photography but when it's done without the other two sides of the triangle and we don't talk about them.........it's like only starting a fire with heat......................F*&^%ing impossible without fuel and oxygen.

Deal with the WHOLE problem or stay at home.

 

[JonFZ300]

All you have to do is take the same pic with different ISO settings and pixel peep to see what it does for your camera. I don't understand what all the fuss is about regarding whether it's actually a component of exposure or not. In the end, it's about the images and image quality.

On my small sensor FZ300, it's irrelevant because I never take it off 100 ISO because I notice changes to IQ even at 200 and 400 is just ugly to my eye.

I'm definitely not anti-learning, but knowing the technicalities and science behind how a camera's ISO function works doesn't change the fact that the only way to exploit that knowledge is to change the ISO setting before taking the picture. And you should know what that does to the image from the test I mentioned above.

 

[Derrel]

I now shoot on an iPhone SE,a Nikon D610, and a Nikon D800. I no longer worry much about ISO level. The ISO is set automatically on the iPhone...and I have No Control over the ISO level...but the program in the iPhone is pretty good.
In the D610 and the D800, the sensor technology is,for practical purposes, ISo-invariant. The DR is extremely good. I seldom exceed ISO 1,600, and with studio flash, often use Iow ISO values, occasionally resorting to the LOW- values to get the right brightness in JPEG images. I have a lot of (now) overly-powerful studio flash gear that was made back in the days of 25 to 100 for color film.