Here is a good example of the Exposure Triangle.

[astroNikon]

Oh boy. WTH is SNR? I don't care. Is it sunny outside or cloudy? Hmmmm

Signal to Noise Ratio ...

 

[wahidovic]

If you watched the video you would see there is no dial or control for SNR but you can control it.
also creating the exposure triangle as a model to help beginners is not a good way to give beginners an understanding of photography and how exposure works now is it?
Maybe that's why so many people are confused with ISO on Digital Camera believing it's part of the Exposure triangle, which it isn't.
With Film Camera's yes, NOT Digital, ISO is applied gain, and that gain is applied after the image is captured, not at the time of the shot, like with film.
ISO / ASA with film works very differently then Digital, it's chemicals built into the film.

and to change it would not be more confusing it's confusing now because people are mislead of what ISO really is.
ISO is nothing more then a way to degrade a picture at any level going above Base ISO mostly anything above 100, the minute you turn that dial above 100 even if it's going to 200, your degrading the image,Yes you are and you can see it if you look carefully, or even more so when you enlarge a print from it.
That grain your seeing with higher ISO it's NOT film Grain it's color degrading and noise your seeing because of that, NOT FILM Grain there is a big difference.
As explained in the video Signal to Noise Ratio, the higher the ISO the more noise you get in your image.
Noise=bad picture...

just like when your driving a car and your listening to your favorite song and as your driving further away from the radio station to the point where your losing signal the song sounds like crap starts to brake apart and gets to the point not even enjoyable..

same thing with applying Higher ISO it's like your driving further away from the radio station and losing the signal..
there is no argument to dispute this fact, nothing you can say makes what this video or what i'm saying here less true.
it's a fact and people should start actually learning the correct way in photography and learn what ISO in digital camera's are.
actually watch the video and learn something and not ask if there is a SNR setting on your camera, there isn't it's

your methods of how you go about taking your shot, being what lens you use and what lighting you apply to your shot, lighting as always taught,
and is very important is a prime element in your signal to noise in your picture lighting is 80% of your exposure control..
ISO is NOT!!!

Hey maybe that's why photographers spend so much money on lighting systems eh?

Donny




As for the video author -- surely there's a listing in the DSM that applies.

The exposure triangle was created as a model to help beginners understand the exposure controls on their cameras and be able to thoughtfully and appropriately set them. It's not a good model but it has been arguably useful doing the job for which it was created.

If, like me, you find the model weak and confusing why in the name of BLEEP BLEEP BLEEPIN' BLEEP would you change it to make it more confusing and downright stupid?!

All of my camera's have a shutter speed control.
All of my lenses have an aperture and I can set the f/stop.
Please show me where on my camera I can set the SNR and then take a picture.

Joe

[/QUOTE]
i think you can control for SNR
and creating the exposure triangle as a model to help beginners

 

[Designer]

What we've got here is an advanced concept that is difficult to understand, and has limited application in the world of amateur photographers. Most of us, as beginners, were introduced to three variables of "the exposure triangle", and were told that is how your camera works. What the video attempts to show is how the firmware in your camera works to produce a viewable image. This is nothing like the analog process of emulsion-based film photography.

 

[astroNikon]

I watched part of The Angry Photographer's video about the so-called Exposure Triangle. I found it so boring, and the graphic so awful that I stopped a few minutes into it,and did not finish watching the video. However, since The Angry Photographer seems so high on SNR as part of exposure, I made a decision, one I hope I shall not regret. I decided that, on Monday, I will be sending my cameras to Nikon's Melville, California repair facility, to have a Signal To Noise Ratio button installed. I figure the $61,567.87 price per camera is well worth it. Of course, I have been drinking a mixture of cranberry and apple juice, diet Rockstar, and tequila, so perhaps my thinking is not quite as clear as The Angry Photographer's thinking.

So...is there anybody else here who thinks paying $61,567.87 (per camera) for having a Signal To Noise Ratio button added to a Nikon D610 and a Nikon D800 makes economic sense? I mean, I think it makes about as much sense as the video does, and I've been drinking tequila and energy drink and cut-rate juice tonight, so I mean,mmmmm, what the heck, right? $120k for the two cameras, and I'll be able to do an Exposure Triangle gymnastic feat worthy of a YouTube video!

(Addendum: ^^^^satire^^^^ alert)

but you'll need 4 SNR dials because there 4 elements of it.

 

[Derrel]

Okay, to be totally honest, I came to photography decades before digital, and the idea of "exposure" is that Exposure is based upon the Intensity x Duration. We take a light level, and an aperture value, together, as ONE, single value, and that is Intensity of the light. Then, the Duration of the light is factored in. The result of Intensity x Duration is the Exposure. Period. If the exposure is correct, the image will be exposed properly. If the exposure is too much or too little, the image will be exposed poorly.

The "so-called exposure triangle" is something I do not agree with. I consider it to be modern bullshit, developed by people who really do not understand the terminology of photography. What the so-called exposure triangle is is a new name for what was long called equivalent exposures. The so-called exposure triangle takes one concept, which is exposure, and adds to it something that is not needed, except to make a teaching device that is primarily useful for noobs who have no concept of how photography works.

The idea of changing ISO as a way to arrive at a different shutter speed or a different aperture, or both settings at a different level, has been around for literally decades. When one wanted a faster shutter speed to stop action, in the film era, one would move from a slow- or medium-speed film to a high-speed film. Exposure setting used would change, based on the film sensitivity speed of the film in the camera. There were equivalent exposure settings, based on film ASA or ISO level, as well as equivalent exposure settings based on the various shutter speeds and f/stops offered by a camera and lens combination.

With today's ISO-invariant sensors, like those in Sony, Nikon, Pentax, and in some Fuji models (and in perhaps other brands' specific offerings) digital cameras, it is now possible to change the Duration portion of the exposure, and cause what appears to be a dark, under-exposed frame, which will then be brightened up in post-processing software. SO, as donny was saying, ISO is NOT "really a part" of exposure in digital systems these days; it's now possible to deliberately under-expose, then brighten in post, with very few problems, with specific sensors.

Anyway...I do not like the so-called exposure triangle, because it is so,so often accompanied by diagrams or notations that indicate that with elevated ISO settings, image quality will go directly to Hell; that is not the case!!! So,so many people making these so-called exposure triangle diagrams show the ISO level accompanied by a clear,sharp image at ISO 100, and an image that looks like crap at ISO 3,200; the ISO 3,200 image being noisy,splotchy,and awful is _not_ accurate, and yet, it is often presented as if that is the gospel truth. Because of the above mentioned reasons, I refer to it as the so-called exposure triangle, not in capital letters, and with the so-called as part of the title.

 

[frank raney]

here is a good example of the Exposure triangle, i always said, that ISO, IS NOT, part of the exposure triangle, ISO is applied gain, and that happens after the picture has been taken, in Digital photography, not Film film is different.

ISO in Digital photography is Applied gain which happens after the picture was taken.
the first of the exposure triangle is Aperture, the second, is shutter speed, and the third, is SNR (Signal to Noise Ratio)

see turning up the ISO is degrading your signal and degrading your picture, each time you turn that ISO up a level higher your applying noise to your image.
now i'm not going to say any more watch this video which will explain this in great detail..
Any one who tells you that ISO is part of the Exposure triangle, doesn't really understand what digital photography is.

Wow, i have never heard anyone try to confuse a new photographer as much as this.....

Nothing has changed from film to digital... in film, the iso number was how sensitive the film was to light. In digital the iso is how sensitive the sensor (film) is to light. Film and digital can get grainy from to sensitive a film/ sensor setting.

A triangle consists of three sides. In photography, f stop, shutter speed, iso. If you do not think iso is part of the triangle, do this.... take your camera, set it for a good exposure at any iso, until your e exposure made is balanced. Drop the f stop one, the bar goes right. Lower the shutter speed one, the bar goes right, raise the iso one, the bar goes right. Wow what a concept, all three controll the light, which is what photos are made of.

Your eyes are sensitive to light. If you look at a bright light and you will see stars (grain) until you're eyes adjust.

Grain, nose, is not applied after a photo is taken. It is applied instantly. But we can not see the effects until after, the film is developed or we look at the digital image.

Photos are made of light and all the sides of the triangle control this light. F stop more or less light, shutter how long. ISO how sensitive.

Now, the more sensitive, the more grain/ noise. On the film days we could not change the iso, we were stuck with what we had, until we finished the roll, and only adjusted the shutter and f stop. In digital we can change film speed (iso) after each shot. Wow, how conveinient.

Now, does iso affect snr. Absoutely, the higher the iso the more noise. BTW, all photos have noise. You just don't see it as easy if the photo is exposed correctly. But why in hell try to confuse noobies with this crap.

If you do not think iso is part of the triangle, turn it all the way up (we can't set it at 0) and try to get a good photo. Never happen.

 

[Ysarex]

here is a good example of the Exposure triangle, i always said, that ISO, IS NOT, part of the exposure triangle, ISO is applied gain, and that happens after the picture has been taken, in Digital photography, not Film film is different.

ISO in Digital photography is Applied gain which happens after the picture was taken.
the first of the exposure triangle is Aperture, the second, is shutter speed, and the third, is SNR (Signal to Noise Ratio)

see turning up the ISO is degrading your signal and degrading your picture, each time you turn that ISO up a level higher your applying noise to your image.
now i'm not going to say any more watch this video which will explain this in great detail..
Any one who tells you that ISO is part of the Exposure triangle, doesn't really understand what digital photography is.

Wow, i have never heard anyone try to confuse a new photographer as much as this.....

Nothing has changed from film to digital... in film, the iso number was how sensitive the film was to light. In digital the iso is how sensitive the sensor (film) is to light.

Nope. In digital ISO does not identify the light sensitivity of the sensor. It specifies a standard output brightness in the JPEG image produced by the camera's image processor.

Film and digital can get grainy from to sensitive a film/ sensor setting.

A triangle consists of three sides. In photography, f stop, shutter speed, iso. If you do not think iso is part of the triangle, do this.... take your camera, set it for a good exposure at any iso, until your e exposure made is balanced. Drop the f stop one, the bar goes right. Lower the shutter speed one, the bar goes right, raise the iso one, the bar goes right. Wow what a concept, all three controll the light, which is what photos are made of.

Your eyes are sensitive to light. If you look at a bright light and you will see stars (grain) until you're eyes adjust.

Grain, nose, is not applied after a photo is taken. It is applied instantly. But we can not see the effects until after, the film is developed or we look at the digital image.

Photos are made of light and all the sides of the triangle control this light. F stop more or less light, shutter how long. ISO how sensitive.

You're as confused as he is -- well, maybe not that much. It is correct to say that ISO is not a determinant factor of exposure. Derrel's definition of exposure above is correct. The definition in Wikipedia is good:

In photography, exposure is the amount of light per unit area (the image plane illuminance times the exposure time) reaching a photographic film or electronic image sensor, as determined by shutter speed, lens aperture and scene luminance. The term ISO is nowhere to be found in that definition. The distinction is important. ISO is nonetheless related to exposure in that it is possible to exposure more or less than desirable.

In a digital camera ISO does 2 things: a) ISO adjusts the camera's metering system such that raising the ISO causes the camera's meter to recalculate a reduced exposure. b) ISO brightens the image in equal degree to the aforementioned reduced exposure to maintain a standard output in the camera processed JPEG.

Now, the more sensitive, the more grain/ noise. On the film days we could not change the iso, we were stuck with what we had, until we finished the roll, and only adjusted the shutter and f stop. In digital we can change film speed (iso) after each shot. Wow, how conveinient.

Now, does iso affect snr. Absoutely, the higher the iso the more noise.

ISO does not effect SNR -- SNR is exposure and ISO as noted above is not a determinant of exposure. In most cameras what ISO does in fact suppresses noise.

BTW, all photos have noise. You just don't see it as easy if the photo is exposed correctly. But why in hell try to confuse noobies with this crap.

That's a tough one. Some noobies would actually prefer to understand the way things work rather than be handed a false model that will potentially confuse them. The Exposure Triangle model causes noobies to make the incorrect assumption that ISO somehow causes noise in a digital photo. They eventually learn to behave based on that false assumption and it can negatively influence their photography.

If you do not think iso is part of the triangle, turn it all the way up (we can't set it at 0) and try to get a good photo. Never happen.

The highest ISO value on my camera (Fuji X-T2) is 12,800. I turned it all the way up and took this photo: test shot of my socks. You probably want to reconsider that "never happen" comment. The ISO function in my camera does help with noise suppression although not a whole lot. That photo of my socks is pretty noise free for ISO 12K on an APS sensor. It helps to understand how it works.

Joe

 

[otherprof]

here is a good example of the Exposure triangle, i always said, that ISO, IS NOT, part of the exposure triangle, ISO is applied gain, and that happens after the picture has been taken, in Digital photography, not Film film is different.

ISO in Digital photography is Applied gain which happens after the picture was taken.
the first of the exposure triangle is Aperture, the second, is shutter speed, and the third, is SNR (Signal to Noise Ratio)

see turning up the ISO is degrading your signal and degrading your picture, each time you turn that ISO up a level higher your applying noise to your image.
now i'm not going to say any more watch this video which will explain this in great detail..
Any one who tells you that ISO is part of the Exposure triangle, doesn't really understand what digital photography is.

I seem to remember the grain getting more apparent when switching from plus-x to tri-x in the old asa days, as we moved from a.s.a. 125 to a.s.a. 400.
The way modern digital cameras handle iso, the "degradation" is frequently not a problem, and the shot is achieved which could not be captured at iso 100, or whatever the "non-degrading" iso is supposed to be - "0"?

 

[Designer]

(a) Wow, i have never heard anyone try to confuse a new photographer as much as this.....

(b) Nothing has changed from film to digital... in film, the iso number was how sensitive the film was to light. In digital the iso is how sensitive the sensor (film) is to light. Film and digital can get grainy from to sensitive a film/ sensor setting.

(c) A triangle consists of three sides. In photography, f stop, shutter speed, iso. If you do not think iso is part of the triangle, do this.... take your camera, set it for a good exposure at any iso, until your e exposure made is balanced. Drop the f stop one, the bar goes right. Lower the shutter speed one, the bar goes right, raise the iso one, the bar goes right. Wow what a concept, all three controll the light, which is what photos are made of.

(d) Your eyes are sensitive to light. If you look at a bright light and you will see stars (grain) until you're eyes adjust.

(e) Grain, nose, is not applied after a photo is taken. It is applied instantly. But we can not see the effects until after, the film is developed or we look at the digital image.

(f) Photos are made of light and all the sides of the triangle control this light. F stop more or less light, shutter how long. ISO how sensitive.

(g) Now, the more sensitive, the more grain/ noise. On the film days we could not change the iso, we were stuck with what we had, until we finished the roll, and only adjusted the shutter and f stop. In digital we can change film speed (iso) after each shot. Wow, how conveinient.

(h)Now, does iso affect snr. Absoutely, the higher the iso the more noise. BTW, all photos have noise. You just don't see it as easy if the photo is exposed correctly. But why in hell try to confuse noobies with this crap.

(i) If you do not think iso is part of the triangle, turn it all the way up (we can't set it at 0) and try to get a good photo. Never happen.

(a) Nobody is trying to confuse anyone.
(b) Lenses and shutters haven't changed much, but the medium that is the receptor has changed a lot.
(c) What you're looking at is the JPG image that your camera has generated so you can see it as a photograph.
(d) Your eyes see "grain"?
(e) "Instantaneous" takes on a new meaning when we are talking about electronics.
(f) Your digital sensor cannot be made more or less sensitive.
(g) How do you change the film speed in digital photography?
(h) So changing the ISO setting affects the S/N ratio? Congratulations, I think that was the point all along.
(i) See Joe's photo referenced above.

 

[dennybeall]

Let me think for a minute. I want a photo and on the camera I set the speed, the shutter and the ISO. I get a photo.
I want to tell a beginner how to take a photo, I do the same.
If I want to show just how complex it can be, I create some complex way to think about taking photos and make a video. Those beginners better get it together and learn from my video!!!!!!!!

 

[TreeofLifeStairs]

here is a good example of the Exposure triangle, i always said, that ISO, IS NOT, part of the exposure triangle, ISO is applied gain, and that happens after the picture has been taken, in Digital photography, not Film film is different.

ISO in Digital photography is Applied gain which happens after the picture was taken.
the first of the exposure triangle is Aperture, the second, is shutter speed, and the third, is SNR (Signal to Noise Ratio)

see turning up the ISO is degrading your signal and degrading your picture, each time you turn that ISO up a level higher your applying noise to your image.
now i'm not going to say any more watch this video which will explain this in great detail..
Any one who tells you that ISO is part of the Exposure triangle, doesn't really understand what digital photography is.

Wow, i have never heard anyone try to confuse a new photographer as much as this.....

Nothing has changed from film to digital... in film, the iso number was how sensitive the film was to light. In digital the iso is how sensitive the sensor (film) is to light.

Nope. In digital ISO does not identify the light sensitivity of the sensor. It specifies a standard output brightness in the JPEG image produced by the camera's image processor.

Film and digital can get grainy from to sensitive a film/ sensor setting.

A triangle consists of three sides. In photography, f stop, shutter speed, iso. If you do not think iso is part of the triangle, do this.... take your camera, set it for a good exposure at any iso, until your e exposure made is balanced. Drop the f stop one, the bar goes right. Lower the shutter speed one, the bar goes right, raise the iso one, the bar goes right. Wow what a concept, all three controll the light, which is what photos are made of.

Your eyes are sensitive to light. If you look at a bright light and you will see stars (grain) until you're eyes adjust.

Grain, nose, is not applied after a photo is taken. It is applied instantly. But we can not see the effects until after, the film is developed or we look at the digital image.

Photos are made of light and all the sides of the triangle control this light. F stop more or less light, shutter how long. ISO how sensitive.

You're as confused as he is -- well, maybe not that much. It is correct to say that ISO is not a determinant factor of exposure. Derrel's definition of exposure above is correct. The definition in Wikipedia is good:

In photography, exposure is the amount of light per unit area (the image plane illuminance times the exposure time) reaching a photographic film or electronic image sensor, as determined by shutter speed, lens aperture and scene luminance. The term ISO is nowhere to be found in that definition. The distinction is important. ISO is nonetheless related to exposure in that it is possible to exposure more or less than desirable.

In a digital camera ISO does 2 things: a) ISO adjusts the camera's metering system such that raising the ISO causes the camera's meter to recalculate a reduced exposure. b) ISO brightens the image in equal degree to the aforementioned reduced exposure to maintain a standard output in the camera processed JPEG.

Now, the more sensitive, the more grain/ noise. On the film days we could not change the iso, we were stuck with what we had, until we finished the roll, and only adjusted the shutter and f stop. In digital we can change film speed (iso) after each shot. Wow, how conveinient.

Now, does iso affect snr. Absoutely, the higher the iso the more noise.

ISO does not effect SNR -- SNR is exposure and ISO as noted above is not a determinant of exposure. In most cameras what ISO does in fact suppresses noise.

BTW, all photos have noise. You just don't see it as easy if the photo is exposed correctly. But why in hell try to confuse noobies with this crap.

That's a tough one. Some noobies would actually prefer to understand the way things work rather than be handed a false model that will potentially confuse them. The Exposure Triangle model causes noobies to make the incorrect assumption that ISO somehow causes noise in a digital photo. They eventually learn to behave based on that false assumption and it can negatively influence their photography.

If you do not think iso is part of the triangle, turn it all the way up (we can't set it at 0) and try to get a good photo. Never happen.

The highest ISO value on my camera (Fuji X-T2) is 12,800. I turned it all the way up and took this photo: test shot of my socks. You probably want to reconsider that "never happen" comment. The ISO function in my camera does help with noise suppression although not a whole lot. That photo of my socks is pretty noise free for ISO 12K on an APS sensor. It helps to understand how it works.

Joe

I saw your picture in one of the other threads and am amazed. So what am I not understanding about how to increase my ISO and not see noise? I tried playing around with it the other day but even at 1600 I could start seeing it.


Sent from my iPhone using ThePhotoForum.com mobile app

 

[Ysarex]

here is a good example of the Exposure triangle, i always said, that ISO, IS NOT, part of the exposure triangle, ISO is applied gain, and that happens after the picture has been taken, in Digital photography, not Film film is different.

ISO in Digital photography is Applied gain which happens after the picture was taken.
the first of the exposure triangle is Aperture, the second, is shutter speed, and the third, is SNR (Signal to Noise Ratio)

see turning up the ISO is degrading your signal and degrading your picture, each time you turn that ISO up a level higher your applying noise to your image.
now i'm not going to say any more watch this video which will explain this in great detail..
Any one who tells you that ISO is part of the Exposure triangle, doesn't really understand what digital photography is.

Wow, i have never heard anyone try to confuse a new photographer as much as this.....

Nothing has changed from film to digital... in film, the iso number was how sensitive the film was to light. In digital the iso is how sensitive the sensor (film) is to light.

Nope. In digital ISO does not identify the light sensitivity of the sensor. It specifies a standard output brightness in the JPEG image produced by the camera's image processor.

Film and digital can get grainy from to sensitive a film/ sensor setting.

A triangle consists of three sides. In photography, f stop, shutter speed, iso. If you do not think iso is part of the triangle, do this.... take your camera, set it for a good exposure at any iso, until your e exposure made is balanced. Drop the f stop one, the bar goes right. Lower the shutter speed one, the bar goes right, raise the iso one, the bar goes right. Wow what a concept, all three controll the light, which is what photos are made of.

Your eyes are sensitive to light. If you look at a bright light and you will see stars (grain) until you're eyes adjust.

Grain, nose, is not applied after a photo is taken. It is applied instantly. But we can not see the effects until after, the film is developed or we look at the digital image.

Photos are made of light and all the sides of the triangle control this light. F stop more or less light, shutter how long. ISO how sensitive.

You're as confused as he is -- well, maybe not that much. It is correct to say that ISO is not a determinant factor of exposure. Derrel's definition of exposure above is correct. The definition in Wikipedia is good:

In photography, exposure is the amount of light per unit area (the image plane illuminance times the exposure time) reaching a photographic film or electronic image sensor, as determined by shutter speed, lens aperture and scene luminance. The term ISO is nowhere to be found in that definition. The distinction is important. ISO is nonetheless related to exposure in that it is possible to exposure more or less than desirable.

In a digital camera ISO does 2 things: a) ISO adjusts the camera's metering system such that raising the ISO causes the camera's meter to recalculate a reduced exposure. b) ISO brightens the image in equal degree to the aforementioned reduced exposure to maintain a standard output in the camera processed JPEG.

Now, the more sensitive, the more grain/ noise. On the film days we could not change the iso, we were stuck with what we had, until we finished the roll, and only adjusted the shutter and f stop. In digital we can change film speed (iso) after each shot. Wow, how conveinient.

Now, does iso affect snr. Absoutely, the higher the iso the more noise.

ISO does not effect SNR -- SNR is exposure and ISO as noted above is not a determinant of exposure. In most cameras what ISO does in fact suppresses noise.

BTW, all photos have noise. You just don't see it as easy if the photo is exposed correctly. But why in hell try to confuse noobies with this crap.

That's a tough one. Some noobies would actually prefer to understand the way things work rather than be handed a false model that will potentially confuse them. The Exposure Triangle model causes noobies to make the incorrect assumption that ISO somehow causes noise in a digital photo. They eventually learn to behave based on that false assumption and it can negatively influence their photography.

If you do not think iso is part of the triangle, turn it all the way up (we can't set it at 0) and try to get a good photo. Never happen.

The highest ISO value on my camera (Fuji X-T2) is 12,800. I turned it all the way up and took this photo: test shot of my socks. You probably want to reconsider that "never happen" comment. The ISO function in my camera does help with noise suppression although not a whole lot. That photo of my socks is pretty noise free for ISO 12K on an APS sensor. It helps to understand how it works.

Joe

I saw your picture in one of the other threads and am amazed. So what am I not understanding about how to increase my ISO and not see noise? I tried playing around with it the other day but even at 1600 I could start seeing it.


Sent from my iPhone using ThePhotoForum.com mobile app

Exposure -- SNR. The noise is in the signal. There are multiple sources of noise in our photos. Some are uncommon like heat build up in the sensor during very long exposures, we can ignore those here. That leaves us two noise sources that matter a) shot noise and b) read noise. Let's take b) first. Read noise is introduced by the sensor electronics while processing the sensor output. Our modern sensors have gotten so bleep bleep good that we can put that one aside as well now; read noise used to be an issue but not any longer. That leaves us with shot noise. Shot noise is in the signal. It's randomness in the light itself and it becomes apparent as the signal weakens. The stronger the signal the more the shot noise is swamped and becomes invisible. So the key is to maintain signal strength.

In that photo I did some cheating -- sort of. I picked a subject with very low contrast deliberately. I made sure there were no bright highlights or deep shadows -- a scene with low DR.

Next step. My Fuji XT-2 has a base ISO of 200. People think base ISO is the ISO of the sensor -- it's not. Its somewhat arbitrarily set by the camera manufacturer and it identifies the exposure needed to render X grey value in the camera processed JPEG. Having done some testing I'm confident the actual ISO of the sensor in my camera if I defined ISO as the exposure needed to take the sensor to saturation would be below 100. Stops are exponential, when we talk about increasing exposure by a stop that's twice as much light. That's huge. So I didn't take that photo at the camera's metered exposure for ISO 12,800. I knew that would leave much of the available sensor capacity unused. I increased the signal. I was able to increase the signal both because the camera is engineered to leave the sensor underutilized and also because of my very low DR lighting. I overexposed by more than two stops beyond the camera metered exposure, and that's the key. I pushed the exposure as far as I could until I reached clipping threshold at that ISO.

CAVEAT: I had the camera on a tripod and I wasn't struggling with the low light problems that drive most photographers to raise ISO to the roof. Many photographers run the ISO up and still fail to get the shutter speed they need and then underexpose a little with their fingers crossed. If that photographer was shooting beside me and struggling to get a fast enough shutter speed he/she may have metered the scene at the camera's ISO 12,800 value and then called it close enough if he/she were still a 1/2 stop under -- fingers crossed. Count up the difference in signal then between my exposure over his/hers -- basically 3 stops -- I'm applying 8 times (2^3) more light. That's really huge.

The JPEG my camera made was actually blown and appeared way overexposed but raw file was at saturation. CAVEAT AGAIN: If you're forced to raise the ISO to the roof it's because you don't have enough light and you can't then do what I did. How are you supposed to increase exposure at ISO 12,800 when you're at ISO 12,800 because you don't have enough light in the first place. So my illustration is academic. I took that photo last year to make the point in a thread in a different forum that the ISO electronics in the camera are not the source of the noise. The noise is in the signal and so increasing the signal as much as 2^3 -- bye bye noise. A little noise filter to finish and there's your answer.

Joe

 

[n614cd]

Continue with the car analogy. How many people here actually know the otto cycle, and what variable timing does for an engine? Or how a constant variable transmission works?

Personally, I care that the brake pedal works, the gas pedal, gear shift and the steering wheel. The rest not so much. I know my car corners better than my wife's, I know her's carries more. To have this knowledge do I need to know the internals? NFW.

The exposure triangle covers the basis of what can be controlled in the camera (excluding flash). It may not be technically precise in terms of symantic definition, but it works. There are tons of other lessons about controlling the environment and using light to compensate. There are thousands of camera reviews to get the right one and lens.

Oh, if you are going into such detail, why in the world do discuss jpeg? You should be shooting in raw.

Last point, here is what I was taught. The point at which the gain from ISO is applied depends on the chip. In still photography we mostly use CMOS which applies the gain per pixel as the signal comes off the chip. If using CCD, the amplification is done after the signal is captured.

Tim

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[petrochemist]

SNR is affected by many factors, the amount of light gathered is only a part of the story. This becomes very noticeable if you use a few older cameras alongside modern ones. My 2006 K100d gives much more noise than it's 2012 brother the K5ii (both having the same sensor size etc), sensor size is another variable...

With many cameras ISO is in effect the amplification of the signal BEFORE A/D conversion. Yes it's after the picture is taken but before the RAW data can be written. It's not like the brightness slider in photoshop which will also effect the effective image for an given exposure.

 

[zulu42]

So if I'm forced to raise the ISO to maintain shutter speed, I should attempt to overexpose a bit to help reduce read noise?
Is there a real world solution to higher ISO = more noise?

I'm trying to apply the information in this thread, but it seems like when I go and shoot, I will still set my camera based on the exposure triangle, and higher ISO will equal more noise...