# Here is a good example of the Exposure Triangle.



## donny1963 (Oct 13, 2018)

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.


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## Ysarex (Oct 13, 2018)

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


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## dennybeall (Oct 13, 2018)

I clicked AGREE to Ysarex's post but that wasn't enough so here's my "I AGREE".
Also my first head scratch-er was wondering where on my camera I could adjust SNR??????


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## Designer (Oct 13, 2018)

dennybeall said:


> Also my first head scratch-er was wondering where on my camera I could adjust SNR??????


You can't adjust it directly.


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## donny1963 (Oct 13, 2018)

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]


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## donny1963 (Oct 13, 2018)

Again if your really watched the video you would know how you adjust SNR.
and scratching your head, yes this is always a factor when trying to tell some one what ISO Really is because most are taught that ISO is part of the exposure triangle.
But hey you think your correct keep doing what your doing you will produce pictures with nosie and the ones who actually
understand this correctly will produce cleaner images..

Being that a FACT!!!!!!!!



dennybeall said:


> I clicked AGREE to Ysarex's post but that wasn't enough so here's my "I AGREE".
> Also my first head scratch-er was wondering where on my camera I could adjust SNR??????


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## donny1963 (Oct 13, 2018)

correct you adjust it on how you go about exposing your shot, being applying lighting, and also what camera and lens you use, all that applies to SNR.
And other factors.. it's all explained in the video, i'm so glad some one created that video no one not any of these knuckle dragging youtubers who claim to know photography 
make videos on various things but NONE of them actually explain ISO and exposure..
If more people would start actually learning the truth about it, i can say they would be producing cleaner images and doing better photography..
Donny





Designer said:


> dennybeall said:
> 
> 
> > Also my first head scratch-er was wondering where on my camera I could adjust SNR??????
> ...


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## Ysarex (Oct 13, 2018)

donny1963 said:


> If you watched the video



I did. That's what the giant emoji was for.



donny1963 said:


> you would see there is no dial or control for SNR but you can control it.



In many or most situations taking a photograph you can not control SNR apart from changing the f/stop or shutter speed which are already variables in the Exposure Triangle. In a lighting condition like this:





What setting on their camera can the average beginner change that will raise the SNR?



donny1963 said:


> 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?



Well you're the one posting videos about it. Why did you bring it up then?



donny1963 said:


> 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.



Of course it's part of the Exposure Triangle. The Exposure Triangle vertices are shutter speed, f/stop and ISO.





Joe


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## Derrel (Oct 13, 2018)

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)


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## Ysarex (Oct 13, 2018)

donny1963 said:


> 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..



Are you sure? The idiot in the video said it was 70%. He also said the other factors added up to 40%. Woah! I found the real secret to the SNR Exposure Triangle 70% + 40% = 100%!

Joe


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## Ysarex (Oct 13, 2018)

Derrel said:


> 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)



Easy there, you're scaring me. Tequila + Rockstar + laughing so hard at that video it hurts = heart attack.

Joe


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## Derrel (Oct 13, 2018)

But what about the $61,000 SNR buttons, Joe? Should I get two cameras modded? Or just the D800?

I want one of those damned SNR buttons!


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## Ysarex (Oct 13, 2018)

Derrel said:


> But what about the $61,000 SNR buttons, Joe? Should I get two cameras modded? Or just the D800?
> 
> I want one of those damned SNR buttons!



Absolutely! You should have one.

Joe


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## jcdeboever (Oct 13, 2018)

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


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## TreeofLifeStairs (Oct 13, 2018)

I didn’t watch the video but does the snr work the other way too? If my camera will shoot at 50 iso is the snr twice as good as it is at 100 iso?


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## astroNikon (Oct 14, 2018)

jcdeboever said:


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


Signal to Noise Ratio ...


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## wahidovic (Oct 14, 2018)

donny1963 said:


> 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.
> ...


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


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## Designer (Oct 14, 2018)

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.


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## astroNikon (Oct 14, 2018)

Derrel said:


> 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.


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## Derrel (Oct 14, 2018)

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.


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## frank raney (Oct 16, 2018)

donny1963 said:


> 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)
> ...




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.


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## Ysarex (Oct 16, 2018)

frank raney said:


> donny1963 said:
> 
> 
> > 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.
> ...



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.



frank raney said:


> 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.
> 
> ...



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.



frank raney said:


> 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.



frank raney said:


> 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.



frank raney said:


> 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


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## otherprof (Oct 16, 2018)

donny1963 said:


> 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)
> ...


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"?


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## Designer (Oct 16, 2018)

frank raney said:


> (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.
> 
> ...


(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.


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## dennybeall (Oct 16, 2018)

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!!!!!!!!


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## TreeofLifeStairs (Oct 16, 2018)

Ysarex said:


> frank raney said:
> 
> 
> > donny1963 said:
> ...



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. 


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## Ysarex (Oct 16, 2018)

TreeofLifeStairs said:


> Ysarex said:
> 
> 
> > frank raney said:
> ...



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


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## n614cd (Oct 16, 2018)

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

Sent from my SM-J737T using Tapatalk


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## petrochemist (Oct 17, 2018)

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.


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## zulu42 (Oct 17, 2018)

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...


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## AlanKlein (Oct 17, 2018)

Raising ISO number adds noise because the electronic circuits are amplifying the signal that the sensor receives and that causes electrical noise the higher the amplification.  The better sensors handle amplification better some there is less noise at higher ISO's.   It's like turning up the volume on loudspeakers.  At some point the speakers start to distort.  Sure the sound is louder, but there are distortions in the sound that are not there at lower volume levels.  You can't make a silk purse from a pig's ear.


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## Ysarex (Oct 17, 2018)

zulu42 said:


> 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?



...to reduce shot noise.



zulu42 said:


> 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...



*Less exposure (less light) will equal more noise* and there's no getting around that. So real world -- the reason we're raising the ISO is because we don't have enough light. The noise is a function of the total light exposure. The only way to beat it is to get more light. This photo: socks at ISO 12K was taken to demonstrate that the noise source is *insufficient exposure*. The camera electronics that brighten the image to compensate (ISO) in fact help to suppress noise, they're not the cause of it.

Joe

EDIT: I encounter this with my students all the time. They think the noise is coming from something involved with the camera's ISO setting -- the exposure triangle nonsense that ISO causes noise. So they're reluctant to raise the ISO. So much so that what they'll do is keep the ISO lower than needed and in fact underexpose for that ISO. In other words they really should raise the ISO to 3200 and hopefully the camera meter is indicating +.3. But instead they'll set the ISO to 1600 with the camera meter indicating -1 and think they're doing the best they can to keep the noise down because 1600 is less noisy than 3200. That's just digging the hole deeper. When forced into a low light condition, expose as much as you possibly can and set the ISO to match.


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## zulu42 (Oct 17, 2018)

Thanks Joe.


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## BananaRepublic (Oct 17, 2018)

Whilst I found his voice hypnotic, overall the clip reminded me of this,


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## zulu42 (Oct 17, 2018)

Okay, the exposure triangle works as us noobs were taught, just remove the misconception that ISO causes noise. Low light causes noise, and underexposing makes it worse.


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## TreeofLifeStairs (Oct 17, 2018)

AlanKlein said:


> Raising ISO number adds noise because the electronic circuits are amplifying the signal that the sensor receives and that causes electrical noise the higher the amplification.  The better sensors handle amplification better some there is less noise at higher ISO's.   It's like turning up the volume on loudspeakers.  At some point the speakers start to distort.  Sure the sound is louder, but there are distortions in the sound that are not there at lower volume levels.  You can't make a silk purse from a pig's ear.



This sounds counter to what Joe is saying though. In your analogy the speaker is producing the noise (the camera in our situation), but from what I’m understanding, Joe is saying it’s the actual signal that has the noise in it. I don’t think the analogy is the same. Even with no music, if I turn my stereo all the way up, I can hear the noise. Joe made a great example by turning up his ISO to the max and still was able to show no apparent noise. 


Sent from my iPhone using ThePhotoForum.com mobile app


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## Designer (Oct 17, 2018)

zulu42 said:


> Okay, the exposure triangle works as us noobs were taught, just remove the misconception that ISO causes noise. Low light causes noise, and underexposing makes it worse.


ISO has nothing to do with exposure, but other than that, you're right.  

The term *applied gain* from your ISO setting implies that the gain is applied to the data *after capture*.  Ergo; the ISO setting is not involved with exposure.  

As I have written on here before; the ISO setting (gain) is applied to the data in order to generate a JPEG file and present it as a viewable image.


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## zulu42 (Oct 17, 2018)

Thanks designer. I feel like I understand that the sensor sees the exposure dictated solely by aperture and shutter speed. ISO setting doesn't alter the data as recorded by the sensor during the exposure.

The point is entirely academic, though, right?  Even though the gain is applied after the capture, you still have to set the ISO prior to exposing, and it affects the brightness of the image we see in 1/3 stop increments just like ss and f stop.


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## AlanKlein (Oct 17, 2018)

TreeofLifeStairs said:


> AlanKlein said:
> 
> 
> > Raising ISO number adds noise because the electronic circuits are amplifying the signal that the sensor receives and that causes electrical noise the higher the amplification.  The better sensors handle amplification better some there is less noise at higher ISO's.   It's like turning up the volume on loudspeakers.  At some point the speakers start to distort.  Sure the sound is louder, but there are distortions in the sound that are not there at lower volume levels.  You can't make a silk purse from a pig's ear.
> ...



Well an analogy is not the same.  If it was the same, it wouldn't be an analogy.  OK, lowering the exposure shutter time or making the aperture smaller allows less photons in.  So you compensate  by increasing the gain of the amps by changing the ISO to a higher number to "normalize" the exposure.  Some noise may be coming from the exposure (less photons) and some from the amps.  Regardless,  the end result is more noise in the final picture file.  That's why you want to use the lowest ISO that's practical.  

By the way, maybe a better analogy would be the shadow slider in post.  You raise the exposure in that area but you start getting artifacts, noise, etc.


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## AlanKlein (Oct 17, 2018)

zulu42 said:


> Thanks designer. I feel like I understand that the sensor sees the exposure dictated solely by aperture and shutter speed. ISO setting doesn't alter the data as recorded by the sensor during the exposure.
> 
> The point is entirely academic, though, right?  Even though the gain is applied after the capture, you still have to set the ISO prior to exposing, and it affects the brightness of the image we see in 1/3 stop increments just like ss and f stop.


+1


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## AlanKlein (Oct 17, 2018)

Here's a good explanation on where noise comes from.
Image noise - Wikipedia


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## Ysarex (Oct 17, 2018)

TreeofLifeStairs said:


> AlanKlein said:
> 
> 
> > Raising ISO number adds noise because the electronic circuits are amplifying the signal that the sensor receives and that causes electrical noise the higher the amplification.  The better sensors handle amplification better some there is less noise at higher ISO's.   It's like turning up the volume on loudspeakers.  At some point the speakers start to distort.  Sure the sound is louder, but there are distortions in the sound that are not there at lower volume levels.  You can't make a silk purse from a pig's ear.
> ...



Yes! You got it! Alan is talking about read noise. Shot noise is in the signal and with today's modern cameras it's shot noise that you're seeing. I'm going to put up another post with some examples.

Joe



TreeofLifeStairs said:


> I don’t think the analogy is the same. Even with no music, if I turn my stereo all the way up, I can hear the noise. Joe made a great example by turning up his ISO to the max and still was able to show no apparent noise.
> 
> 
> Sent from my iPhone using ThePhotoForum.com mobile app


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## Ysarex (Oct 17, 2018)

zulu42 said:


> Thanks designer. I feel like I understand that the sensor sees the exposure dictated solely by aperture and shutter speed. ISO setting doesn't alter the data as recorded by the sensor during the exposure.



YES! And the scales fell from his eyes!



zulu42 said:


> The point is entirely academic, though, right?



No! Got a little more work to do then.



zulu42 said:


> Even though the gain is applied after the capture, you still have to set the ISO prior to exposing, and it affects the brightness of the image we see in 1/3 stop increments just like ss and f stop.



Let's try and clean up a couple of things going on here and pull in some stuff from other recent posts. There's a little confusion here about the source of noise. There are multiple sources of noise in a digital photo but most of us only have to worry about shot noise and read noise. The noise Alan has described in a couple posts is read noise. Let's have a look at it: To do that I had to reach back a decade and dig an old camera out of the drawer. I used to shoot a little 1/1.7 sensor Samsung compact. So I just took this photo with it at ISO 1600 which is pretty high for 10 year old tech and a sub-postage stamp size sensor:






Not bad for ISO 1600 and that downsized image is noise filtered. But now let's look at the image at 100% with no noise filtering. We're also going to look at a second image side by side. The second photo was shot without moving the camera at the exact same exposure but with the ISO set back to 80. Both raw files. The second photo was brightened in post to match the first shot at 1600:





There's a difference in the noise -- the ISO 80 shot that was brightened has worse noise. Raising ISO suppresses noise in many cameras and especially older cameras that generate read noise. So raising the ISO to 1600 helped reduce noise. The ISO 80 shot is noisier (color trouble as well) because the 10 year old tech in the electronics generates some read noise which the ISO gain otherwise helps suppress.

In that case sitting there is my new compact camera a Canon G7Xmkii. It is virtually free of read noise. They have engineered it out of this camera. The same goes for many modern cameras now especially from Nikon, Sony and Fuji. They are virtually free of read noise. Let's use the G7 then and repeat the above test.





I metered the scene for ISO 1600 and took that photo and then left the exposure the same and re-took the shot at ISO 125. Here's that side by side:





The noise is the same in both. Unlike above with the Samsung, ISO 1600 provided no advantage and the data in the two raw files will render the same final image when the ISO 125 shot is brightened in post. Read noise was a reality we had to pay attention to a decade ago. The Wiki article Alan cited is dated. Read this instead: what's that noise. Buy a camera today and especially tomorrow and read noise is rapidly becoming a worry from the past.

Zulu! This is where you pay attention again. Is this just an academic exercise? NO! When the ISO function in a digital camera brightens the image it does so before or during ADC (analog to digital conversion) which is before the raw file is created and written. That makes what ISO does permanent in a raw file. And when ISO brightens the data coming from the sensor it reduces DR. Look above at the jar of rice behind the camera (photo from the G7) and the specular highlight on the jar just below the rim. That's the photo brightened from the ISO 125 shot which produced a nearly black JPEG. Now look at that same highlight in this shot:





Specular highlights should clip and in the ISO 1600 shot directly above that highlight is clipped -- it's clipped in the raw file and there's nothing I can do about that the data is lost. That highlight was clipped by the ISO brightening of the sensor data and we in fact call that ISO clipping. The DR in the raw file is reduced and a histogram of the raw file will show the clipping. But in the ISO 125 shot that highlight is not clipped. It's not even close to clipped and I was able to retain it in processing as a diffuse highlight. That's not academic -- that's a new capability we now have with cameras that are functionally free of read noise.

Joe


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## zulu42 (Oct 17, 2018)

Joe, thanks very much for the great explanation. I do see how it isn't entirely academic in that- know your sensor and use ISO as needed to reduce noise. Often that means raise the ISO, especially in cameras that aren't real new.

I shoot a ton in low exposure situations. Not just low light because even in daylight I'm pumping ISO up to get the shutter speeds I like for shooting birds. It was actually a struggle to get over avoiding ISO at the cost of underexposing. Still, shooting birds seems like constantly at or near the limit of low light. Low light Cooper's Hawk

If there's any way to apply this knowledge to get my d800 a few more stops worth of nice images... should I try to ETTR more as the ISO goes up?


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## donny1963 (Nov 3, 2018)

Designer said:


> zulu42 said:
> 
> 
> > Okay, the exposure triangle works as us noobs were taught, just remove the misconception that ISO causes noise. Low light causes noise, and underexposing makes it worse.
> ...




Correct, ISO has nothing to do with Exposure, people think it does because if they turn up the ISO the picture looks like it's getting better exposure, all it's doing is applying gain..
By the way what the ISO does happens after the picture has been taken,, yeah people think it's like FILM, It's not!!!
the ISO takes place after the picture is taken and then the camera's processing writes the picture to the data card.

basically a DSLR camera is nothing more then a Computer with a lens attached to it..
Some People just don't understand, the Lower the iso you use the better quality your picture will be providing you took the correct exposure and all.
Always a rule use the Lowest ISO number you can use, other wise the higher you turn it up the more noise and the more of your picture information you lose..

the noise your seeing from high ISO , some people think it's the same as Grain on Film,  IT'S NOT!!   it's garbage and degraded data of your picture, you lose contrast, dynamic range,  Color all that, it gets broken up and looks like crap.. Film grain is the old days where you would use a higher ISO / ASA film the chemicals embeded in the film is created that way, and it's not noise and garbage like digital..
Taking pictures with a digital camera is not the same as using film, 
Back in the film days i use to shoot slides ,  FUJIFILM Fujichrome Velvia 50 the ISO i used was 50, i use to get the sharpest pictures using that.
Best i ever used, it was mainly designed for landscape photography, but i did use it for portraits as well..
the color was saturated a bit, but in a good way, and very very sharp, because of the low ISO.

The only drawback to using that was (Light) very unforgiving shooting in low, and even during daylight you still had to be careful doing portraits, you had to use a flash at all times otherwise it would pickup shadows very easy, and ruin your shot, unless you use the fill flash..
just the shade from a subjects jaw or hat the shadows would be very dark because of the LOW ISO.
for portraits i mainly used a 50 M 1.4 Lens, shooting at an aperture higher then 3.5 was difficult with ISO 50


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## donny1963 (Nov 3, 2018)

TreeofLifeStairs said:


> Ysarex said:
> 
> 
> > frank raney said:
> ...


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## InFlight (Nov 3, 2018)

My brain hurts.


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