# Noise apps = higher ISO settings?



## mcasan (Jul 25, 2021)

Before the days of powerful noise reduction software (NoNoise, DeNoise..etc.). There was a limit you would push you camera’s ISO setting to give you max shutter speed for shooting sports, wildlife…etc. With the new noise reduction software apps, how much further are you pushing your camera ISO because you think or know that the noise app can mitigate the extra noise?

For example, if you would set your auto IOS to a max of 1600, do you now set auto to 3200 or 6400?


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## Paul_DS256 (Jul 25, 2021)

mcasan said:


> how much further are you pushing your camera ISO



I think the first question is how noisy your sensor/camera is, as the ISO increases, even before considering denoise software. 

My shooting style is to manually set the shutter and aperture and let the ISO float. I was not satisfied with the noise level of my D5300 at ISO 6400. I opted to move to a full-frame D750. It has less noise at 6400 and I feel I can shoot with a higher ISO even though the specs say they have the same base ISO range. Here's a good video showing the difference in shots with the same ISO between the D5300 and D750.

So, there upper end will depend on the sensor/camera and how much noise you are willing to live with depending on the use of the photo.

Now, after giving you my opinion, I'm looking forward to what the experts say


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## clee01l (Jul 25, 2021)

mcasan said:


> ?
> 
> For example, if you would set your auto IOS to a max of 1600, do you now set auto to 3200 or 6400?


I don’t use 3rd party noise reduction software.

My first digital camera was a Pentax. ISO 800 was pushing its limits. Older versions of Lightroom needed help with noise reduction. Jump ahead to today. I shoot with a 48mp Nikon mirror less camera. ISO 1600 is the starting point if it is not a bright sunny day. ISO 3200 and ISO 6400 are almost noise free and can be handled without a 3rd party noise tool.


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## tspear (Jul 25, 2021)

I mostly stopped using noise reduction years ago, more because I felt the tradeoff was not worth it. But kept it as a tool.

Now with a 61mp Sony, I have yet to use any noise reduction. Part of the reason I made the jump away from Classic is after testing the latest Topaz with the large files I no longer feel a need for it, the sensors are just so good for my level of shooting.

Tim (not a pro)

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## Jimmsp (Jul 25, 2021)

I don't really know how to answer you as so much depends on your camera and sensor, along with the subject and the lighting. I kind of know where you are going with the question, but I don't think there is an easy answer. I shoot a Canon 90D, which has improved noise over much of its ISO range.  But the noise I see at a given ISO will be larger than what Cletus sees at the same ISO. 
I have tested my camera and lenses on good test targets for color and sharpness over a range of settings and light. I have also tested much of the latest noise reduction software on these test photos as well as on actual field shots. I know what to expect. 
And when I have auto ISO set, I always look to see what ISO the camera is shooting. I might readjust shooting parameters if I don't like it.
Today, I use LR Classic and Topaz DeNoise AI - dependent upon the photo, ISO, and how I will eventually show and use it. For my "best" photos taken at ISO's of 800 or more I will generally use Topaz DeNoise, but I am always watching out for artifacts and loss of detail or color.

So, I have not changed my camera's auto ISO max, but I will many times shoot at higher ISOs than I did a few years & cameras ago.
That includes subjects like birds in flight where I will sometimes push shutter speed and ISO to combos I didn't use before.


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## Johan Elzenga (Jul 25, 2021)

Don’t increase the ISO. Google for “ISO invariance” to understand what to do and why.


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## clee01l (Jul 26, 2021)

Johan Elzenga said:


> Don’t increase the ISO. Google for “ISO invariance” to understand what to do and why.



Thanks for pointing out ISO invariance. That explains what I have been experiencing in my high end Nikon cameras for some time. 

I shoot in manual mode with a fixed ISO, and adjust the shutter speed and f-stop to get the exposure that I seek. DoF is sometimes important and very small f-stop values are sometimes required. Only then will I adjust the ISO to get the f-stop I need. 

For me, ISO does not need to vary in camera and can be compensated for exposure by changing the shutter speed or f-stop. Post processing corrects the exposure if needed.

I can see when shooting JPEG that in camera ISO settings can be important since the output product is fixed in the camera.


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## Paul_DS256 (Jul 26, 2021)

Johan Elzenga said:


> Don’t increase the ISO. Google for “ISO invariance” to understand what to do and why.


"ISO Invariance" is definitely a subject which causes "Mr. Gumby my brain hurts". I'd forgotten about it (hate headaches) but decided to dive into it once again more for more own education on letting the ISO float.

I found this article to be very useful "ISO Invariance Explained" (I have no idea how accurate the author is). In particular these points:

"If your camera sensor is perfectly ISO invariant, there is no penalty in noise if you brighten a photo in post-production rather than increasing your ISO in-camera. They are functionally the same. No cameras are perfectly ISO invariant starting from base ISO; however, some are quite close, and many cameras become ISO invariant starting at a high enough ISO value (once the camera begins to “simulate” ISO values)."
"The simulated high-ISO values in your camera also only perform digital amplification of the highest “real” ISO on your camera. They simply multiply the binary number, just like your post-processing software does."
"If you need to use ISO 12,800 in order to get a photo that has proper brightness, but the highest real / native ISO on your camera (the last one with any additional analog amplification) is ISO 3200, it is better to use ISO 3200 and brighten the image later. There is no penalty, and you will get more dynamic range".
Further research on "Native ISO" led me to this article "ISO Chart: Everything You Need to Know About ISO".

"The native ISO is the range of ISO values that uses amplification to enhance the light information gathered by your sensor."
"To achieve ISO values beyond your native ISO range, your camera uses post-processing to simulate or extrapolate what your image would look like at the extended ISO values."
So, in relation to my cameras:

"Nikon's exclusive technology also helps the D5300 (cropped sensor) achieve a standard [native?] ISO sensitivity range of 100 to 12800, and it's extendable to an ISO 25600 equivalent (Hi 1)".
Nikon D750 (full frame sensor) "[Native?] ISO sensitivity ... 100 to 12800"
Note, both use the Nikon Expeed 4 processor

So then, why in the video I referenced above, was the D5300 so much "noiser" than the D750? Some of it has to do with a cropped sensor versus a full frame.  In this article "Digital Camera Database - Nikon D750 vs. Nikon D5300", it clearly shows how much bigger the FX is over the DX. More importantly, this introduces:

"Pixel pitch tells you the distance from the center of one pixel (photosite) to the center of the next. It tells you how close the pixels are to each other.  The bigger the pixel pitch, the further apart they are and the bigger each pixel is. Bigger pixels tend to have better signal to noise ratio and greater dynamic range."
So, "The Nikon D750 is a 24-megapixel full-frame camera. So its individual pixels are physically larger, and therefore much more sensitive to light than a 24-megapixel crop-sensor camera like a Canon Rebel T6 or Nikon D3300 [or D5300]."

In relation to the OP original question of


mcasan said:


> With the new noise reduction software apps, how much further are you pushing your camera ISO because you think or know that the noise app can mitigate the extra noise?
> 
> For example, if you would set your auto IOS to a max of 1600, do you now set auto to 3200 or 6400?



I still think it's a matter of sensor/camera and understanding native ISO range. There are some cameras that are considered "ISO invariant" but for those aren't, testing and understanding your camera's native ISO range will determine where and when you need denoise tools IMHO.


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## Jimmsp (Jul 26, 2021)

clee01l said:


> ......
> 
> I shoot in manual mode with a fixed ISO, and adjust the shutter speed and f-stop to get the exposure that I seek. DoF is sometimes important and very small f-stop values are sometimes required. Only then will I adjust the ISO to get the f-stop I need.
> 
> ...


The important takeaway from the "ISO Invariance" discussion for me is that an underexposure of a couple of stops is fine. LR can easily correct that and the inherent noise is less than in a "properly exposed" shot.

Two of the important shooting subjects that this effects for me are birds in flight, including hummingbirds, and hand held macros of bees & bugs on wild flowers.
Here, the drivers are shutter speed to stop the wings, and DOF. For bif, I am generally at a minimum of 1/2000 sec. And I need fast focus so I'll often use auto ISO. 
But in answer to the OP's original question, I have not increased my auto ISO max. I'll take a smaller ISO as the noise reduction software is better than last year. For these handheld macros fast shutter speed and apertures of f/16 or smaller drive a high ISO; but again, I don't "properly expose" with ISO and I will accept a lower exposure which I can correct with LR.   I am perfectly happy to trade off 1/3000 sec or f/22 for an underexposed shot I can correct well. I hope this makes sense.
If I shot these at ISO 100, I wouldn't get enough light in to auto focus, and the photo would be underexposed by so much that I could not recover anything.


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## clee01l (Jul 26, 2021)

Jimmsp said:


> …
> Two of the important shooting subjects that this effects for me are birds in flight, including hummingbirds, and hand held macros of bees & bugs on wild flowers.
> Here, the drivers are shutter speed to stop the wings, and DOF. For bif, I am generally at a minimum of 1/2000 sec. And I need fast focus so I'll often use auto ISO. …


For the same subjects, I shoot Manual with a set ISO. Like you BIFs get a shutter speed of 1/2000s and the f-stop is adjusted to bring the subject into approximately the correct exposure. 
The DoF on macro shots is often 2-4 mm and a 25mm dragonfly 3/4 pose only will get part of the animal in focus even using a very small aperture. 


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## Johan Elzenga (Jul 26, 2021)

The most important thing to remember about using ISO invariance is that it increases the effective dynamic range. Let’s say that a proper exposure of a scene would be 1/125 sec, F4 and ISO 6400. If you use the fact that your camera is ISO invariant from ISO 1600 onwards (assuming it is) and so you shoot at 1/125 sec, F4 and ISO 1600 (and correct for this underexposure in Lightroom), then you create two extra stops of headroom in your highlights before they’ll blow out.


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## clee01l (Jul 26, 2021)

Johan Elzenga said:


> The most important thing to remember about using ISO invariance is that it increases the effective dynamic range. Let’s say that a proper exposure of a scene would be 1/125 sec, F4 and ISO 6400. If you use the fact that your camera is ISO invariant from ISO 1600 onwards (assuming it is) and so you shoot at 1/125 sec, F4 and ISO 1600 (and correct for this underexposure in Lightroom), then you create two extra stops of headroom in your highlights before they’ll blow out.



This was exactly my post processing experience that I did not have a good explanation for until you brought up ISO invariance.


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## Paul_DS256 (Jul 26, 2021)

Johan Elzenga said:


> If you use the fact that your camera is ISO invariant from ISO 1600 onwards (assuming it is)


I'd say that is the challenge. How ISO invariant is your camera?


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## davidedric (Jul 27, 2021)

I'm also confused.

If I utilise the ideas behind ISO invariance and bring up the lightness in Lightroom, say, I gain dynamic range without noise penalty.

If I ETTR and bring the lightness down in Lightroom, I gain the benefits of an increase in real exposure and I think reduced noise.

Which to use when?


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## Johan Elzenga (Jul 27, 2021)

davidedric said:


> I'm also confused.
> 
> If I utilise the ideas behind ISO invariance and bring up the lightness in Lightroom, say, I gain dynamic range without noise penalty.
> 
> ...


ETTR is of benefit in situations where you can use a normal, base ISO value. No camera is ISO invariant at base ISO. Using ISO invariance (which you could call ‘Exposure To The Left’) is only of benefit in situations where you would normally use a much higher ISO value, and where there are also highlights that could easily blow out. In practise that means that you use this for night photography.


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## Jimmsp (Jul 27, 2021)

Johan Elzenga said:


> ETTR is of benefit in situations where you can use a normal, base ISO value. No camera is ISO invariant at base ISO. Using ISO invariance (which you could call ‘Exposure To The Left’) is only of benefit in situations where you would normally use a much higher ISO value, and where there are also highlights that could easily blow out. In practise that means that you use this for night photography.



Johan - this has been a fascinating discussion.  And I think I have understood it.  Your "Exposure to the left" is a great summation. I am pretty sure that I can use this in many situations for my birds in flight as well as for some insect macros. I'll go back and check some older photos.

This would be a wonderful educational topic for the more experienced members of my small community photo club.  If you run across a good ppt presentation that I could present I would be most grateful. 
Thanks again.


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## Paul_DS256 (Jul 27, 2021)

I'm still confused about using expose-to-the-left. Do you do this when the required ISO setting for an image is:

In range of the native ISO
In the extend/extrapolated ISO's
Only if your camera is ISO Invariant.


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## Johan Elzenga (Jul 27, 2021)

Paul_DS256 said:


> I'm still confused about using expose-to-the-left. Do you do this when the required ISO setting for an image is:
> 
> In range of the native ISO
> In the extend/extrapolated ISO's
> Only if your camera is ISO Invariant.


Pretty much every camera is ISO-invariant at _some_ point. For older cameras it may well be the highest non-extended ISO value, for modern cameras it may be quite a bit lower than that. The trick is to find out what that point is. Then you can use ETTL as soon as you would otherwise go over that point. 

Finding out is not that difficult. What you need to do is the following: set up a shoot that is correctly exposed with your highest non-extended ISO value, so for example ISO 6400. Let's say that you'll find that 1/60 sec, F5.6 and ISO 6400 is the correct exposure for this scene. Set the shutter speed and aperture to these values manually. Now make a series of exposures where you lower the ISO speed one stop each time, so in this example you shoot the following series:

1/60 sec, F5.6, 6400 ISO (i.e. correctly exposed)
1/60 sec, F5.6, 3200 ISO (i.e. one stop underexposed)
1/60 sec, F5.6, 1600 ISO (i.e. two stops underexposed)
1/60 sec, F5.6, 800 ISO (i.e. three stops underexposed)
1/60 sec, F5.6, 400 ISO (i.e. four stops underexposed)

Load these images in Lightroom, select them all with the 6400 ISO shot as 'most selected' image and then choose 'Photo - Develop Settings - Match Total Exposures'. Lightroom will now correct the underexposed images by setting the exposure to +1, +2, +3 and +4, meaning all images will be identical as far as the exposure is concerned. Now zoom in to 1:1 and compare the four underexposed images with the first image. Look at the noise level. If your camera is ISO-invariant at say 1600 ISO, then you will see no noticeable difference between photo 1 (6400 ISO) and 3 (1600 ISO, +2 stops corrected in Lightroom), but you will see that photo 4 (800 ISO, +3 stops corrected in Lightroom) is getting worse than photo 1. The example below may be a little difficult to judge because I could not post it at full size, but if you look carefully you will probably agree that ISO-invariance of this camera is reached at 1600 ISO.

So now that I know that this camera starts to be ISO-invariant at 1600 ISO, I will use 1600 ISO (and underexpose) in all cases where I would normally need to use a higher value to get the correct exposure.


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## clee01l (Jul 27, 2021)

Paul_DS256 said:


> I'm still confused about using expose-to-the-left. Do you do this when the required ISO setting for an image is:
> 
> In range of the native ISO
> In the extend/extrapolated ISO's
> Only if your camera is ISO Invariant.



I haven’t used ETTR for many years. I think it might have been valid with fixed ISO/ASA film, but for years with a manual mode I have been fixing the ISO setting, I have been using exposure settings to slightly under expose (ETTL)


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## Johan Elzenga (Jul 27, 2021)

clee01l said:


> I haven’t used ETTR for many years. I think it might have been valid with fixed ISO/ASA film, but for years with a manual mode I have been fixing the ISO setting, I have been using exposure settings to slightly under expose (ETTL)


Clee, I think you misunderstand what ETTR is. It has nothing to do with (and is not applicable for) film photography. It is an exposure technique for digital, based on the fact that digital sensors are linear.


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## Paul_DS256 (Jul 28, 2021)

Thanks @Johan Elzenga, great technique I'll try on my D5300. I'm curious to see how it behaves.


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## mcasan (Jul 28, 2021)

I wonder if invariance is in, at least part, a function of sensor size, pixel size, and pixel density on the sensor.


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## tspear (Jul 28, 2021)

mcasan said:


> I wonder if invariance is in, at least part, a function of sensor size, pixel size, and pixel density on the sensor.


Pixel size may play. But at the end of the day, it is about the sensor design. 
If you look at the photons to photos website you will see for my Sony A7R4, that it effectively has a dual gain system for ISO. Base is 100, you then see a decrease in dynamic range as amplification takes place until 320 when it is reset. So for my camera i really should only use two values for ISO; 100 or 320. However practical comes into play also. When the EV gets below about -3 the auto focus does not work very well. So in that case for the autofocus to work I need to raise the ISO beyond 320, even though the camera will never do as good a job as Lr.

Tim

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## clee01l (Jul 28, 2021)

Johan Elzenga said:


> Clee, I think you misunderstand what ETTR is. It has nothing to do with (and is not applicable for) film photography. It is an exposure technique for digital, based on the fact that digital sensors are linear.



I think I understood the principle. I never understood the reasoning. ETTR was to push the Exposure curve to the right instead of a normal Bell shaped curve. Now that I think about it, there were no histograms with film. So, in that sense, you are correct. ETTR never worked for me shooting RAW. I always got better results if I under exposed slightly and corrected shadows in Post.


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## tspear (Jul 28, 2021)

ETTR dates back to the original digital cameras I think. And many of them has narrow ranges, so in a typical sunny image it was better to blow out the sky and get the details from the shadows.

I personally never did it, by the time I really started to look at photography as a real hobby the cameras had passed that stage, and I got better images ETTL.

Tim

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## Johan Elzenga (Jul 28, 2021)

ETTR is based on the following principle:  a sensor is linear, out eyes are not. That means that the sensor data have to be ‘gamma corrected’ to give the same effect as our eyes do. Because a sensor is linear however, half the number of shades will be in the first (brightest) stop, 25% will be in the second stop, etcetera. If you shoot a relatively dark scene, you may lose 50% or more of what the sensor could record, because you record nothing in the first stop. At the same time you will be struggling to get enough meaningful information in the darkest stops (read: to get a signal that is higher than the noise).

That is when ETTR makes sense. You overexpose the image, in order to push all the information up to the right of the histogram. The result is an increased signal to noise ratio everywhere in the image. In post processing you correct for this overexposure, of course. The result is a cleaner image, which is most obvious in the darkest parts. Unfortunately, this is not as easy as it sounds. You may blow highlights if you are not careful and do not understand when to use this and when not to use this. Many people think that ETTR simply means you overexpose every image and correct that in post, but that is nonsense. You only overexpose those scenes that have headroom to do this.


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## tspear (Jul 28, 2021)

@Johan Elzenga 

Yeah, I follow the theory. But this is reality.  What is that trite phrase, in theory, theory and practice are the same, in practice they are not.

However I have never found a shot for me ever made ETTR make sense. Yeah, you push to the right until you get blow outs, with the theory that you get more details in the shadows. When I first got the Canon 6D, I spent a lot of time doing bracketed shots, seven of them separated by half stops.

For my old Canon, if the range was that dynamic, bracket shots worked much better (for obvious reasons). If I could not get bracket shots fore some reason, I cannot recall a single instance where ETTR would have worked better for me. It would have always caused blow outs, and most often the area with blow outs is the area I am interested in (e.g. family indoor holiday photos).
It could be that I never was in the perfect situation where ETTR would work better. However like I said I have taken bracket shots stepping a half EV. Everytime the negative shots worked out better or brackets were needed.

Tim

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## Johan Elzenga (Jul 28, 2021)

I agree that there are far fewer situations where ETTR works well than some people think. The problem is that there are often small highlights that would blow out, even if most of the image is very dark. But because taking a digital photo is free, you can simply try by shooting multiple exposures.


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## clee01l (Jul 28, 2021)

Johan Elzenga said:


> I agree that there are far fewer situations where ETTR works well than some people think. The problem is that there are often small highlights that would blow out, even if most of the image is very dark. But because taking a digital photo is free, you can simply try by shooting multiple exposures.


And this multiple exposure becomes the principle behind HDR.


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## Johan Elzenga (Jul 28, 2021)

clee01l said:


> And this multiple exposure becomes the principle behind HDR.


Yes, if you merge them. In this case I suggested it as a way to find the best image for post processing.


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## PhilBurton (Jul 28, 2021)

Johan Elzenga said:


> The most important thing to remember about using ISO invariance is that it increases the effective dynamic range. Let’s say that a proper exposure of a scene would be 1/125 sec, F4 and ISO 6400. If you use the fact that your camera is ISO invariant from ISO 1600 onwards (assuming it is) and so you shoot at 1/125 sec, F4 and ISO 1600 (and correct for this underexposure in Lightroom), then you create two extra stops of headroom in your highlights before they’ll blow out.


Is this approach the same as Expose To The Right?


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## Johan Elzenga (Jul 28, 2021)

PhilBurton said:


> Is this approach the same as Expose To The Right?


No, this is exposure to the left…


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## Johan Elzenga (Jul 28, 2021)

Johan Elzenga said:


> No, this is exposure to the left…


Well, actually it isn’t either. The two techniques are very different. In the ETTR technique you do actually change the *exposure*, to utilise the headroom that the sensor has. You increase the amount of light that falls onto the sensor, and correct that in post production.

If you use the ISO-invariance of your camera, you do not change the exposure. The shutter speed and aperture remain the same, so the amount of light that falls on the sensor remains the same. The only thing you change is the ISO-setting, which is how much the sensor signal is amplified. Again, this is changed in post production, which is about the only thing the techniques have in common.


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## prbimages (Jul 29, 2021)

tspear said:


> ... I cannot recall a single instance where ETTR would have worked better for me. It would have always caused blow outs ...



Not really, because ETTR by definition is _setting the exposure as far to the right as possible *without *causing blowouts_.


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## PhilBurton (Jul 29, 2021)

Johan Elzenga said:


> Well, actually it isn’t either. The two techniques are very different. In the ETTR technique you do actually change the *exposure*, to utilise the headroom that the sensor has. You increase the amount of light that falls onto the sensor, and correct that in post production.
> 
> If you use the ISO-invariance of your camera, you do not change the exposure. The shutter speed and aperture remain the same, so the amount of light that falls on the sensor remains the same. The only thing you change is the ISO-setting, which is how much the sensor signal is amplified. Again, this is changed in post production, which is about the only thing the techniques have in common.


So right now, I hate to admit it, I'm confused.  How do I set the camera's metering, if it isn't Programmed (on Nikon cameras), Aperture Priority, or Shutter Priority?

Phil Burton


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## tspear (Jul 29, 2021)

Neither. You will be in manual mode.
Well technically you could set the EV compensation and fix the ISO then control  either the shutter or aperture, but that is a lot more convuluted.

Tim

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## mcasan (Jul 29, 2021)

For me the reason to use higher ISO is so my shutter speed can go high enough to freeze action in wildlife.    I can see knowing the invariance ISO value that should be max ISO if shooting still images.   That is good to know.    For most of my shots I need a focused image with frozen action.   That can drive the need for a higher ISO that might be OK for a still subject.


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## PhilBurton (Jul 29, 2021)

tspear said:


> Neither. You will be in manual mode.
> Well technically you could set the EV compensation and fix the ISO then control  either the shutter or aperture, but that is a lot more convuluted.
> 
> Tim
> ...


If my camera allows me to fix the ISO at just one value, then can I still shoot in some automatic mode?  My Nikon D3 unfortunately does not have an ISO Priority exposure mode.


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## Johan Elzenga (Jul 29, 2021)

PhilBurton said:


> If my camera allows me to fix the ISO at just one value, then can I still shoot in some automatic mode?  My Nikon D3 unfortunately does not have an ISO Priority exposure mode.


No, because then the camera would take the fixed ISO into account when setting the aperture and shutter speed, so you _would_ change the exposure. The result would be a perfectly exposed picture (but possibly blurred because of the long shutter speed) that does not need to be corrected in post production, so you would not get the benefit of the extra dynamic range. This technique must be used with manual settings. ISO priority won’t work either.  If you don’t want to use those or don’t know how, then don’t use this technique.


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## Johan Elzenga (Jul 29, 2021)

mcasan said:


> For me the reason to use higher ISO is so my shutter speed can go high enough to freeze action in wildlife.    I can see knowing the invariance ISO value that should be max ISO if shooting still images.   That is good to know.    For most of my shots I need a focused image with frozen action.   That can drive the need for a higher ISO that might be OK for a still subject.


I think you misunderstand how this technique works. There is no reason why it could not be used for action photography like wildlife or sport. If you would normally shoot a wildlife picture at say 1/2000 sec and F4, then you would use these same settings if you take the ISO invariance into account. *You would still shoot at 1/2000 and F4!!* The difference is that you‘d normally use perhaps 6400 ISO to get a perfectly exposed shot, and now you keep the camera at 1600 ISO and so you will get a two stops underexposed shot. That underexposure you then fix in Lightroom. Look at it as if you could change the ISO in post production.


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## clee01l (Jul 29, 2021)

PhilBurton said:


> So right now, I hate to admit it, I'm confused. How do I set the camera's metering, if it isn't Programmed (on Nikon cameras), Aperture Priority, or Shutter Priority?


Manual mode gives you complete control over Aperture, Shutter speed and ISO.   Set the ISO to the setting that benefits you most and then the two Nikon dials can control shutter and aperture.   The exposure meter is visible in the viewfinder to show you which way to move the dials for the exposure setting that you wish.


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## clee01l (Jul 29, 2021)

PhilBurton said:


> If my camera allows me to fix the ISO at just one value, then can I still shoot in some automatic mode?  My Nikon D3 unfortunately does not have an ISO Priority exposure mode.


There are no benefits of shooting in some automatic mode.   Manual IS automatic in a sense.   ISO is adjustable (though not as easy as Aperture or Shutter Speed).   In Manual Mode I set the ISO,  then either set the shutter speed  or the aperture depending on whether I need to freeze the action or maximize DoF.   The I can move the other dial on the camera to "dial in " the correct exposure.  Setting Aperture priority allows you to adjust the aperture and the Camera will  automatically  adjust the  Shutterspeed.  For Shutter priority, it is reversed.   In order to force the camera to under expose or over expose, you need to adjust the EV.  

Shooting Manual, you set the EV to zero.  Adjust the ISO, then the shutter and aperture to under expose (ETTL) or over expose(ETTR). Each mark on the Viewfinder exposure meter is one EV increment  ( EV  increment can be set on 1/3 or 1/2 stops)


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## Jimmsp (Jul 29, 2021)

Johan Elzenga said:


> I think you misunderstand how this technique works. There is no reason why it could not be used for action photography like wildlife or sport. If you would normally shoot a wildlife picture at say 1/2000 sec and F4, then you would use these same settings if you take the ISO invariance into account. *You would still shoot at 1/2000 and F4!!* The difference is that you‘d normally use perhaps 6400 ISO to get a perfectly exposed shot, and now you keep the camera at 1600 ISO and so you will get a two stops underexposed shot. That underexposure you then fix in Lightroom. Look at it as if you could change the ISO in post production.


I intend to back into it. With my 90D, I get very manageable noise; and a large range of native ISO. I ran Johan's suggested ISO variations the other day and was very pleased with the results.
So I intend to still shoot at f/4 and ISO6400 (or what ever) where I might be perfectly exposed at 1/2000, and the change the shutter speed to 1/4000 where I will be clearly underexposed. But that underexposed shot is easily corrected in LR. It's the higher shutter speed that has concerned me before, and this discussion has relieved that "fear".
I like the comment "Look at it as if you could change the ISO in post production. "


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## mcasan (Jul 29, 2021)

Johan Elzenga said:


> I think you misunderstand how this technique works. There is no reason why it could not be used for action photography like wildlife or sport. If you would normally shoot a wildlife picture at say 1/2000 sec and F4, then you would use these same settings if you take the ISO invariance into account. *You would still shoot at 1/2000 and F4!!* The difference is that you‘d normally use perhaps 6400 ISO to get a perfectly exposed shot, and now you keep the camera at 1600 ISO and so you will get a two stops underexposed shot. That underexposure you then fix in Lightroom. Look at it as if you could change the ISO in post production.


So amplify the signal in camera using higher ISO setting or, amplify the signal in post production via Develop/ACR.      So it is a question of which path gives the best signal to noise ration when completed.


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## Johan Elzenga (Jul 29, 2021)

mcasan said:


> So amplify the signal in camera using higher ISO setting or, amplify the signal in post production via Develop/ACR.      So it is a question of which path gives the best signal to noise ration when completed.


No, it’s a bit different. There are different sources of noise. For some sources it doesn’t matter when the signal is amplified, for another source it does matter. ISO invariance means that the latter source has become so small, that it doesn’t really matter anymore when the signal is amplified. ISO Invariance Explained


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