Manual iso

[4dampadac]

Is there any reason why others use manual iso in manual mode instead of auto ?

 

[David1961]

It seems to me to make sense set the control that actually controls what it is you want to control. You set the EC directly, to something other than 0, when you know that you want the image lightness to be different from what it would be with the default metering solution, and you set the EC to 0 when the default solution is what you want.

Why do you care what exact ISO you have? What reason do you have for wanting to control the ISO setting?

You haven't really answered either of these two questions. Instead you gave an unusual reason for why you want to use manual ISO setting in general, without reference to a particular ISO value.

An exact ISO, unlike an exact f-number or an exact shutter speed or an exact EC setting, doesn't correspond directly to any visible aspect of a photo.

I'd have thought you'd care about how light or dark the image was, relative to the typical metering solution.

If I rely on auto-ISO, I have to carefully monitor the shutter speed when out-and-about.

Why? You are in manual mode. The shutter is at whatever you set it at. If you are likely to forget what you set it at, you should just check what it is. If you can neither remember the shutter speed in Manual mode, nor remember to check what it is when you don't remember what it is, you have a serious memory problem or a technique problem, or both. Effective technique for use of manual mode requires making settings choices deliberately for each new scene. If you are forgetting to do that, you need to work on your shooting discipline.

E.g. I have the shutter set at 1/150s to capture routine action and then stop and take a picture of a shady statue.

To me, the fact that I have switched subjects is sufficient indication that I need to think about my aperture and shutter settings. No further mnemonic is needed.

If I'm on manual ISO it will be obvious that the image is under-exposed and I can dial back the shutter speed. If I'm on auto-ISO I might forget about my high shutter speed and shoot at a higher ISO, degrading image quality. That's an artificial example, but I find that it's more effort to "police" auto ISO than to quickly manually set the property with a flick of my wrist. a bright rock to a dark bush. In both situations the bird

Even in situations where my manual ISO is off I'm almost always under-exposing (fixable with ISO-invariant sensors)

Not really fixable with either invariant or variant sensors. You cannot fix the fact that your underexposure captured less light and therefore caused unnecessary noisiness. is the dynamic range of your camera so low that blown highlights are always more of a problem than noise?

whereas the auto-ISO general over-exposes (tougher to correct).

Only tougher if it blew desired highlight detail. If it didn't, it is actually easier to fix than underexposure.

Especially with my compact camera I really want to minimize ISO to maximize quality,

Setting base ISO only maximizes noise performance if there is no highlight headroom at the widest aperture and slowest shutter you are willing to use. Otherwise, for just about every digital stills camera, you will get better noise performance by increasing ISO to just before the point of clipping.

and controlling exposure trade-offs with a 1" sensor requires more finesse than the metering mode can handle.

How so?

It's clear from how you word your replies that you're working out some personal issues by being aggressive and condescending on forums. You're not worth replying to and I sincerely hope you redirect your efforts into a better quality of life.

But what FingerPainter posted is totally accurate.

When people start posting insults, it convinces me they do not have the ability to prove their point.

I am not trying to change the way anyone does things here, as I said before it comes down to personal preferences.

If you need your opinions to be taken seriously, why not post something that proves opposing opinions to be wrong which you haven't done.

In the mean time, thank you for your opinions

 

[BrentSchumer]

There's no right answer on people's preferred methods; they are entirely subjective.

The original question was "why do people use manual ISO" not "convince me that manual ISO is the best method for all photographers."

It's fair to say "it might simplify your shooting to try X instead of Y." But telling people that they're wrong to prefer doing things a certain way and rejecting their explanations for that subjective preference is just asinine.

 

[almostgreen]

The higher the ISO the smaller your dynamic range, meaning that as ISO goes up the highlights are more at risk for blowing out . on a very sunny day you might want to give up your optimal aperture and shutter speed settings to stay at ISO 100

 

[Bob A L]

It does not directly affect the amount of light delivered to the sensor. It is a setting used by the camera after the exposure to manage the lightness with which a JPEG is rendered.

With the above we have common total agreement. I certainly agree that iso setting has no effect whatsoever on the light that hits the sensor (or film for that matter) but iso does have an effect on the photo that is the only thing we can view with digital when relating to jpeg output from a camera. I have no idea what goes on with the "raw" you guys use and don't care as it does not affect my photos in any way. So I still hold that for me and a huge percentage of average Joe's out in the world making pictures with their digital cameras and phones that ISO is in fact one of three (all equally important) settings controlling the exposure as seen in prints and digital images produced by our equipment. And possibly leading some new photographers using jpegs out of their equipment by giving them the idea that ISO setting does not affect the exposure of their images is misleading and can cause them problems.

So to clarify my comments - my statement should be - In straight out of camera jpeg images ISO setting is just as important as shutter speed and aperture when considering the lightness or brightness (in past history referred to as exposure) of images.

 

[Bill Ferris]

With my cameras if I want to be in full control of the result and use manual settings, there would be no choice to use auto iso. I would be giving automatic control back to the camera. Any time I give the camera the ok to choose iso, aperture, and/or shutter speed, it's the boss and typically does a fine job. But on the occasions that I want to be in control and make my own mistakes it's gonna be all or nothing,

When you're shooting based on the camera's meter and you choose two of three settings, the third one is calculated. It has to be one value. You're not giving control to the camera; you're letting it do a simple calculation.

Ah, but which calculation?

Cameras are designed and built to make the world look middle gray in tone. Put a camera in full auto, fill the frame with a white sheet of paper, and make a photo. Now fill the frame with a black sheet of paper and make a photo. Both photos will look the same. They'll be neither white nor black. They'll be middle gray because that's what cameras are designed to do.

How does this apply in the real world? Imagine a person outside in a park on a fine day with billowing, friendly clouds in the sky. Grass and trees and flowers surround then. For the sake of discussion, we'll say they're on vacation and carrying a camera with an 18-200mm mounted. Our intrepid photographer sets the zoom at 18mm for a wide shot. There's abundant sunlight so they choose f/8 and 1/250. The camera is set to auto ISO. They frame a shot and take the photo. It looks great. The camera chose an ISO of 200.

Now the photographer zooms in to 200mm to capture some details in the scene. They compose and take three different photos. Reviewing the images, our traveler notices the camera chose three different ISOs; a different ISO for each shot. Why? The settings were the same, the quality of light was the same. Why would the camera choose different ISOs?

It chose different ISOs to make the composition look middle gray in tone. It had no idea that the first shot was of a dark green pine tree that, in full manual at good settings, would read as about -2/3 stop from on-meter. It had no idea that the second shot was of a white cloud shaped like a puppy dog that will read as about +2/3 stop from on-meter in manual at good settings. It certainly had no idea that the third photo was of a friendly black dog trotting over to say hello, an animal that will meter at least 1-2 stops below 0 at settings that will accurately render the color and tone of its coat.

In the photos, the pine looks a tad bright and the cloud just a skosh dingy. They'll be easy to tweak in LR mobile. The dog looks gray - just way wrong - but should also be recoverable. None of the photos is unrecoverable so the "fix it in post" approach can totally be applied. Our traveler could also have applied some exposure compensation to force the camera to select an ISO that would have rendered the scene perfectly. There's always more than one way to skin the proverbial cat.

Or he could have chosen to shoot in full manual and dial-in an ISO along with the other settings. After making the wide shot, he could have used the exact same settings to make photos of the tree and cloud, and they would've looked fine. The light didn't change. There was no need to change settings.

The dog presents an interesting challenge. He trotted over to greet the traveler. The photographer may have changed shutter speed from 1/250 to 1/500 and let auto-ISO do its thing. The camera would still have chosen an ISO 1-2 stops too high but, again, that can be fixed in post. Personally in full manual, I'd have combined the shutter speed change with a change in f-stop from f/8 to 5.6 to maintain the exposure.

This brings up a totally legit issue that always gets raised in these discussions: how many settings do you want to manage and can that be done in the time available? My personal experience is that managing all three is doable even when things are happening quickly. Not everybody has the same experience or shares that assessment and that's to be expected. It's why cameras are so highly configurable. They can be set to fit an individual's aesthetic and, as long as you're coming home with photos you like, why change?

So, I'm not offering full manual as an approach everybody should adopt. It is a reliable method and is at least worth trying. But it's not for everybody.

 

[BrentSchumer]

With my cameras if I want to be in full control of the result and use manual settings, there would be no choice to use auto iso. I would be giving automatic control back to the camera. Any time I give the camera the ok to choose iso, aperture, and/or shutter speed, it's the boss and typically does a fine job. But on the occasions that I want to be in control and make my own mistakes it's gonna be all or nothing,

When you're shooting based on the camera's meter and you choose two of three settings, the third one is calculated. It has to be one value. You're not giving control to the camera; you're letting it do a simple calculation.

Ah, but which calculation?

Cameras are designed and built to make the world look middle gray in tone. Put a camera in full auto, fill the frame with a white sheet of paper, and make a photo. Now fill the frame with a black sheet of paper and make a photo. Both photos will look the same. They'll be neither white nor black. They'll be middle gray because that's what cameras are designed to do.

How does this apply in the real world? Imagine a person outside in a park on a fine day with billowing, friendly clouds in the sky. Grass and trees and flowers surround then. For the sake of discussion, we'll say they're on vacation and carrying a camera with an 18-200mm mounted. Our intrepid photographer sets the zoom at 18mm for a wide shot. There's abundant sunlight so they choose f/8 and 1/250. The camera is set to auto ISO. They frame a shot and take the photo. It looks great. The camera chose an ISO of 200.

Now the photographer zooms in to 200mm to capture some details in the scene. They compose and take three different photos. Reviewing the images, our traveler notices the camera chose three different ISOs; a different ISO for each shot. Why? The settings were the same, the quality of light was the same. Why would the camera choose different ISOs?

It chose different ISOs to make the composition look middle gray in tone. It had no idea that the first shot was of a dark green pine tree that, in full manual at good settings, would read as about -2/3 stop from on-meter. It had no idea that the second shot was of a white cloud shaped like a puppy dog that will read as about +2/3 stop from on-meter in manual at good settings. It certainly had no idea that the third photo was of a friendly black dog trotting over to say hello, an animal that will meter at least 1-2 stops below 0 at settings that will accurately render the color and tone of its coat.

In the photos, the pine looks a tad bright and the cloud just a skosh dingy. They'll be easy to tweak in LR mobile. The dog looks gray - just way wrong - but should also be recoverable. None of the photos is unrecoverable so the "fix it in post" approach can totally be applied. Our traveler could also have applied some exposure compensation to force the camera to select an ISO that would have rendered the scene perfectly. There's always more than one way to skin the proverbial cat.

Or he could have chosen to shoot in full manual and dial-in an ISO along with the other settings. After making the wide shot, he could have used the exact same settings to make photos of the tree and cloud, and they would've looked fine. The light didn't change. There was no need to change settings.

The dog presents an interesting challenge. He trotted over to greet the traveler. The photographer may have changed shutter speed from 1/250 to 1/500 and let auto-ISO do its thing. The camera would still have chosen an ISO 1-2 stops too high but, again, that can be fixed in post. Personally in full manual, I'd have combined the shutter speed change with a change in f-stop from f/8 to 5.6 to maintain the exposure.

This brings up a totally legit issue that always gets raised in these discussions: how many settings do you want to manage and can that be done in the time available? My personal experience is that managing all three is doable even when things are happening quickly. Not everybody has the same experience or shares that assessment and that's to be expected. It's why cameras are so highly configurable. They can be set to fit an individual's aesthetic and, as long as you're coming home with photos you like, why change?

So, I'm not offering full manual as an approach everybody should adopt. It is a reliable method and is at least worth trying. But it's not for everybody.

Thank you for articulating this so well.

 

[jrtrent]

But you miss the point - I don't shoot raw - have absolutely no need for it. As explained I have absolutely no intention to process any photo I take in my computer, My camera does that. I admit to messing up on occasion, and either have to throw something away or break down and fix it in the computer, but don't need raw to do that. And my exposure (lightness) does change if I take two photos under the same lighting using the same aperture and shutter speed but with different ISO settings unless I fix them in the computer later. As to cameras I use Nikon, Panasonic, Olympus, Sony, and Canon and they all work the same.

And all are probably ISO invariant to one degree or another. Whether you choose to take advantage of that, is up to you.

From the posts I've seen on ISO invariance and a brief search, the assumption is that how bright or dark the final image is is determined in post-processing. Like Bob A L and some others, my goal is always to have an out-of-camera JPEG that is already just as bright or dark as I want it. My guess is that by exposing that way, I'm not taking advantage of ISO invariance.

From a Google search, "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."

And if you've got a system for choosing settings that produce photos you like, there's probably no reason to change.

Nicely stated.

All that said, the fact remains that ISO is not an exposure setting. It does not directly affect the amount of light delivered to the sensor. It is a setting used by the camera after the exposure to manage the lightness with which a JPEG is rendered.

The amount of light delivered to the sensor is not something I think about. I can't measure it, my camera does not give me a read-out of it to take into consideration before pressing the shutter release, and it does not necessarily have any bearing on whether the resulting picture will have the brightness I desire or not. As you've pointed out in other posts, in the same light and using the same exposure settings, a dark subject will result in less light hitting the sensor than a bright subject, but that doesn't mean I want to change the exposure or ISO settings--a dark subject should appear darker than a bright subject.

What I can know and take into consideration are the intensity of the light falling on the subject and the sensitivity of the film or sensor I am using. With slide film, sensitivity was a condition determined by what I loaded into the camera (ISO 100 Fujifilm Astia was my only film for most of my final years shooting film); with digital, sensitivity is a setting I can adjust on my camera.

No, neither film speed nor digital ISO setting directly affect the light falling on the film or sensor, but either is something I need to take into consideration when determining what combination of shutter speed and aperture I'm going to need to get the image brightness I want.

 

[Dennis]

When you're shooting based on the camera's meter and you choose two of three settings, the third one is calculated. It has to be one value. You're not giving control to the camera; you're letting it do a simple calculation.

Ah, but which calculation?

The only way it can be wrong is if the metering system produced an incorrect EV. And you have control over that.

As you say, there's more than one way to skin a cat and if someone prefers to shoot in manual rather than Auto ISO in M, more power to them. In addition to a general preference, there are times when one or the other can be more efficient. I only object to the notion that Auto ISO in M means "giving automatic control back to the camera".

- Dennis
--
Gallery at http://kingofthebeasts.smugmug.com

 

[FingerPainter]

• Bob A L wrote:

Just to modern hi tech photographers maybe. To a lot of us old guys, for 40 years or so I and any of my friends would have called a photo that was too dark underexposed and a photo that was too light overexposed and some of us still do. Things used to be so much simpler.

Before joining DPR forums I used to think like you until I had it drummed into me what exposure actually is and that ISO is not an exposure control.

Suddenly things became much clearer in terms of the roles aperture, shutter speed and ISO play.

Using incorrect terminology, although yes it is common, does not make it correct and should not be thrust upon newbies to photography.

I just wish that the "old guys" you refer to updated their knowledge on what exposure actually is in reality otherwise they leave themselves wide open to justifiably being corrected, at least for the sake of correctly educating newbies.

I posted the definition of exposure I accept and I see you are still unable to answer my question to you regarding what definition of exposure you accept.

Maybe you don't have one?

Maybe he didn't define exposure, but I like his definitions of underexposed and overexposed. Below is a way of thinking about exposure that I like. Perhaps you used to like something similar:

"A photograph's exposure determines how light or dark an image will appear when it's been captured by your camera. Believe it or not, this is determined by just three camera settings: aperture, ISO and shutter speed . . ." https://www.cambridgeincolour.com/tutorials/camera-exposure.htm

CiC is wrong about so many other technical matters, that it is no surprise they are wrong about this too, What they say in bold means that if you take your camera out on a bright sunny day and manually set it to {1/125, f/16, ISO 100} and take a picture, and then take it into a windowless room, turn out all the lights and take another shot with the same settings, the second photo will be just as light or dark as the first. You should know that's not true.

The truth is that the exposure is determined by three things:

1. the T-stop of the lens (approximated by f-number)
2. the length of time the shutter was open ("shutter speed")
3. how much light was in the scene ("scene luminance")

and how light or dark a SOOC JPEG would look depends on two things:

1. the exposure, and
2. the ISO setting

If my brother asks what exposure I gave that picture I sent him of a gnome our aunt sent decades ago, I can say the exposure was 1/15 second, f/1.8, and ISO 100.

You can say that, but it won't actually tell him what the exposure was. It will tell him what your three most common camera settings were. Without knowing how much light was on the gnome you won't know the exposure.

 

[Bob A L]

omg - I give up

 

[jrtrent]

If my brother asks what exposure I gave that picture I sent him of a gnome our aunt sent decades ago, I can say the exposure was 1/15 second, f/1.8, and ISO 100.

You can say that, but it won't actually tell him what the exposure was. It will tell him what your three most common camera settings were. Without knowing how much light was on the gnome you won't know the exposure.

My brother, of course, would be looking at the picture and see that the tonal values look "normal," about the same as his eyes would see them were he at my home, and be able to work out that light conditions were about EV 6, nine stops below normal sunny f/16 lighting (EV 15). What he still wouldn't know, and what I don't know, is "the amount of light that hit the sensor per unit area," which is how David1961 defined exposure. That will vary with the subject reflectivity.

My gnome is rather dark, so there would be less light hitting the sensor than if I used the same settings to take a picture of something lighter-toned that was sitting in that same light. If you meter off of a gray card instead of the objects themselves, the meter doesn't suggest any change in exposure or ISO settings, and the objects retain their natural tonal values in the resulting pictures, whether light or dark.

 

[FingerPainter]

With my cameras if I want to be in full control of the result and use manual settings, there would be no choice to use auto iso. I would be giving automatic control back to the camera. Any time I give the camera the ok to choose iso, aperture, and/or shutter speed, it's the boss and typically does a fine job. But on the occasions that I want to be in control and make my own mistakes it's gonna be all or nothing,

When you're shooting based on the camera's meter and you choose two of three settings, the third one is calculated. It has to be one value. You're not giving control to the camera; you're letting it do a simple calculation.

Ah, but which calculation?

Cameras are designed and built to make the world look middle gray in tone. Put a camera in full auto, fill the frame with a white sheet of paper, and make a photo. Now fill the frame with a black sheet of paper and make a photo. Both photos will look the same. They'll be neither white nor black. They'll be middle gray because that's what cameras are designed to do.

Cameras are provided with an EC control so when what they are metering isn't actually middle grey the photographer can bias the meter for the actual lightness of the subject.

How does this apply in the real world? Imagine a person outside in a park on a fine day with billowing, friendly clouds in the sky. Grass and trees and flowers surround then. For the sake of discussion, we'll say they're on vacation and carrying a camera with an 18-200mm mounted. Our intrepid photographer sets the zoom at 18mm for a wide shot. There's abundant sunlight so they choose f/8 and 1/250. The camera is set to auto ISO. They frame a shot and take the photo. It looks great. The camera chose an ISO of 200.

The camera is broken and the photographer is incompetent. Sunny 16 tells us that with abundant sunlight we can shoot at 1/125 f/16 ISO 100. F/8 is two stops more exposure and 1/250 is one stop less, therefore our ISO needs to be one stop lower than 100, not one stop higher. 1/250, f/8, ISO 200 is sort of correct for cloudy days when there are no shadows, but if the camera is capable of ISO 100, {1/125, f/8, ISO 100} would be better for grass, trees, flowers, clouds and non-energetic dogs. For frisky dogs, {1/500, f/4, ISO 100} might be better.

Now the photographer zooms in to 200mm to capture some details in the scene. They compose and take three different photos. Reviewing the images, our traveler notices the camera chose three different ISOs; a different ISO for each shot. Why?

Because he foolishly didn't adjust his metering for the different subjects, nor did he lock his exposure. Either is an available option that would have avoided these problems.

The settings were the same, the quality of light was the same. Why would the camera choose different ISOs?

Because the scenes meter differently. Auto-ISO is an autoexposure mode. It relies on the meter, If you use an autoexposure mode and rely on the meter, you need to bias the meter accordingly. This goes for every mode on the camera except M without Auto-ISO.

It chose different ISOs to make the composition look middle gray in tone. It had no idea that the first shot was of a dark green pine tree that, in full manual at good settings, would read as about -2/3 stop from on-meter. It had no idea that the second shot was of a white cloud shaped like a puppy dog that will read as about +2/3 stop from on-meter in manual at good settings. It certainly had no idea that the third photo was of a friendly black dog trotting over to say hello, an animal that will meter at least 1-2 stops below 0 at settings that will accurately render the color and tone of its coat.

In the photos, the pine looks a tad bright and the cloud just a skosh dingy. They'll be easy to tweak in LR mobile. The dog looks gray - just way wrong - but should also be recoverable. None of the photos is unrecoverable so the "fix it in post" approach can totally be applied. Our traveler could also have applied some exposure compensation to force the camera to select an ISO that would have rendered the scene perfectly. There's always more than one way to skin the proverbial cat.

Or he could have chosen to shoot in full manual and dial-in an ISO along with the other settings. After making the wide shot, he could have used the exact same settings to make photos of the tree and cloud, and they would've looked fine. The light didn't change. There was no need to change settings.

The dog presents an interesting challenge. He trotted over to greet the traveler. The photographer may have changed shutter speed from 1/250 to 1/500 and let auto-ISO do its thing. The camera would still have chosen an ISO 1-2 stops too high but, again, that can be fixed in post. Personally in full manual, I'd have combined the shutter speed change with a change in f-stop from f/8 to 5.6 to maintain the exposure.

Now the dog trots behind the man and decides to investigate smells at the base of the gazebo. The dog is now in full shade, and the full manual settings are incorrect. But with Auto-ISO and EC you still get the "correct" lightness.

So what can we conclude from all this?

When subject illumination is constant but metering solutions will vary, using a manually set ISO in M mode will result in no settings changes needed, unless motion blur or DOF requirements change.

Another way to accomplish the same thing is to lock exposure while composing the first shot and keep it locked for the others. and use Auto ISO. That way no settings changes are required except for DoF and motion blur adjustments, you get consistant exposure, and you avoid the photographer guessing the wrong ISO to use (like 200 hen 100 is available and usable).

When metering solutions will vary only with the light, and the light will vary, Auto-ISO requires no adjustments, except for DoF and motion blur, to get constitnt lightness. But Manually set ISO will require per-shot adjustments.

This brings up a totally legit issue that always gets raised in these discussions: how many settings do you want to manage and can that be done in the time available? My personal experience is that managing all three is doable even when things are happening quickly.

Congratulations. You are a more mechanically-skilled photographer than I am,. When I am shooting sports or BIF, I don't seem to be able to manage three different settings changes per shot without missing shots.

Not everybody has the same experience or shares that assessment and that's to be expected. It's why cameras are so highly configurable. They can be set to fit an individual's aesthetic

and an individual's learned technique

and, as long as you're coming home with photos you like, why change?

Because you come come home with even better photos? For some, good enough is good enough. For others, continuous improvement is a goal.

So, I'm not offering full manual as an approach everybody should adopt. It is a reliable method and is at least worth trying. But it's not for everybody.

That's a fair assessment.

 

[almostgreen]

Which is it? A google search gives both answers.

 

[jrtrent]

• Bob A L wrote:

Just to modern hi tech photographers maybe. To a lot of us old guys, for 40 years or so I and any of my friends would have called a photo that was too dark underexposed and a photo that was too light overexposed and some of us still do. Things used to be so much simpler.

Before joining DPR forums I used to think like you until I had it drummed into me what exposure actually is and that ISO is not an exposure control.

Suddenly things became much clearer in terms of the roles aperture, shutter speed and ISO play.

Using incorrect terminology, although yes it is common, does not make it correct and should not be thrust upon newbies to photography.

I just wish that the "old guys" you refer to updated their knowledge on what exposure actually is in reality otherwise they leave themselves wide open to justifiably being corrected, at least for the sake of correctly educating newbies.

I posted the definition of exposure I accept and I see you are still unable to answer my question to you regarding what definition of exposure you accept.

Maybe you don't have one?

Maybe he didn't define exposure, but I like his definitions of underexposed and overexposed. Below is a way of thinking about exposure that I like. Perhaps you used to like something similar:

"A photograph's exposure determines how light or dark an image will appear when it's been captured by your camera. Believe it or not, this is determined by just three camera settings: aperture, ISO and shutter speed . . ." https://www.cambridgeincolour.com/tutorials/camera-exposure.htm

CiC is wrong about so many other technical matters, that it is no surprise they are wrong about this too, What they say in bold means that if you take your camera out on a bright sunny day and manually set it to {1/125, f/16, ISO 100} and take a picture, and then take it into a windowless room, turn out all the lights and take another shot with the same settings, the second photo will be just as light or dark as the first. You should know that's not true.

Apparently you were unable to understand their rain bucket analogy:

"Achieving the correct exposure is a lot like collecting rain in a bucket. While the rate of rainfall is uncontrollable, three factors remain under your control: the bucket's width, the duration you leave it in the rain, and the quantity of rain you want to collect. You just need to ensure you don't collect too little ("underexposed"), but that you also don't collect too much ("overexposed")."

In their analogy the "rate of rainfall" represents differing amounts of light. The rainfall, or light intensity, is greater outdoors on a bright sunny day than it is indoors under normal home lighting. They are in no way suggesting that the same settings result in the same image brightness under any and all lighting conditions.

 

[jrtrent]

omg - I give up

Seems like a good idea to me, too. Fingerpainter and others are bright fellows, but they believe they've been "enlightened" in some way, and cannot let others of us enjoy and discuss the hobby in any way but theirs, insisting that we need to be "corrected" in our thinking. I will say this much for them, they are tireless at it!

 

[Bill Ferris]

But you miss the point - I don't shoot raw - have absolutely no need for it. As explained I have absolutely no intention to process any photo I take in my computer, My camera does that. I admit to messing up on occasion, and either have to throw something away or break down and fix it in the computer, but don't need raw to do that. And my exposure (lightness) does change if I take two photos under the same lighting using the same aperture and shutter speed but with different ISO settings unless I fix them in the computer later. As to cameras I use Nikon, Panasonic, Olympus, Sony, and Canon and they all work the same.

And all are probably ISO invariant to one degree or another. Whether you choose to take advantage of that, is up to you.

From the posts I've seen on ISO invariance and a brief search, the assumption is that how bright or dark the final image is is determined in post-processing. Like Bob A L and some others, my goal is always to have an out-of-camera JPEG that is already just as bright or dark as I want it. My guess is that by exposing that way, I'm not taking advantage of ISO invariance.

From a Google search, "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."

And if you've got a system for choosing settings that produce photos you like, there's probably no reason to change.

Nicely stated.

All that said, the fact remains that ISO is not an exposure setting. It does not directly affect the amount of light delivered to the sensor. It is a setting used by the camera after the exposure to manage the lightness with which a JPEG is rendered.

The amount of light delivered to the sensor is not something I think about. I can't measure it, my camera does not give me a read-out of it to take into consideration before pressing the shutter release, and it does not necessarily have any bearing on whether the resulting picture will have the brightness I desire or not.

Though, light - and the amount the camera has to work with - is arguably the single most important factor determining image quality. I'm distinguishing image from creative quality, here. There are certainly photos which have been made that, despite being blurry, noisy, or otherwise compromised from an IQ standpoint, are creatively brilliant and notable as such.

While a camera's setting may not tell us how many photons will be collected, they're a clear indication of exposure that is comparatively high, low, or somewhere in-between. Within the creative intent of the photographer, maximizing exposure without blowing highlights goes a long way toward ensuring good image quality.

As you've pointed out in other posts, in the same light and using the same exposure settings, a dark subject will result in less light hitting the sensor than a bright subject, but that doesn't mean I want to change the exposure or ISO settings--a dark subject should appear darker than a bright subject.

I would agree. Well put.

What I can know and take into consideration are the intensity of the light falling on the subject and the sensitivity of the film or sensor I am using. With slide film, sensitivity was a condition determined by what I loaded into the camera (ISO 100 Fujifilm Astia was my only film for most of my final years shooting film); with digital, sensitivity is a setting I can adjust on my camera.

No, neither film speed nor digital ISO setting directly affect the light falling on the film or sensor, but either is something I need to take into consideration when determining what combination of shutter speed and aperture I'm going to need to get the image brightness I want.

I'm with you on this. I like to get the image as close to "right" in camera as I'm able and selection of ISO is part of that equation.

What I would encourage with respect to ISO, is adopting language that adequately describes how one manages, chooses or uses that setting, but that does not promulgate the misunderstanding that it's an exposure setting: a setting directly impacting how much light is delivered to the sensor. This is more for the benefit of new or novice photographers who are just learning their way around a camera. A more accurate understanding of what ISO is and does can open creative doors a person may not have known existed.

 

[David1961]

It does not directly affect the amount of light delivered to the sensor. It is a setting used by the camera after the exposure to manage the lightness with which a JPEG is rendered.

With the above we have common total agreement. I certainly agree that iso setting has no effect whatsoever on the light that hits the sensor (or film for that matter) but iso does have an effect on the photo that is the only thing we can view with digital when relating to jpeg output from a camera. I have no idea what goes on with the "raw" you guys use and don't care as it does not affect my photos in any way.

No, that is not quite correct.

The raw data does affect your photo.

Whether you realise it or not, your camera is initially recording raw data and then if you choose to have the camera output jpegs then the camera will simply process the raw data according to the "Picture Style" settings you have chosen in your camera settings to produce the jpeg for you. Whether you choose to have the raw data saved as well in a file by the camera obviously depends on whether the option is available.

The photographer using the raw data from their camera is in effect telling the camera not to produce a jpeg (unless you choose to shoot raw + jpeg) and that they will produce the jpeg them self in post processing using a raw converter application.

So I still hold that for me and a huge percentage of average Joe's out in the world making pictures with their digital cameras and phones that ISO is in fact one of three (all equally important) settings controlling the exposure as seen in prints and digital images produced by our equipment.

For me, ISO is the least important of the 3 - aperture, shutter speed, ISO.

Setting the widest aperture to give my DOF and the slowest shutter speed to meet my motion blur requirements without clipping highlights and hence maximising exposure are by far much more important than ISO.

My camera does a very good job 99% of the time setting an appropriate ISO via Auto ISO for the scene.

If the image is still too dark for my liking I simply use EC to raise the ISO in camera (preferable) or I can lighten the image in post (less preferable)

And possibly leading some new photographers using jpegs out of their equipment by giving them the idea that ISO setting does not affect the exposure of their images is misleading and can cause them problems.

ISO does not directly affect the exposure at all because the effect of ISO is applied after the shutter has closed and no more light can hit the sensor.

Exposure = amount of light that hits the sensor per unit area.

Only scene illumination, aperture and shutter speed can affect exposure.

For a given scene illumination:

1. f/5.6, 1/200s, ISO 100

and

2. f/5.6, 1/200s, ISO 200

are exactly the same exposure but setting 2 will output a lighter image

So to clarify my comments - my statement should be - In straight out of camera jpeg images ISO setting is just as important as shutter speed and aperture when considering the lightness or brightness (in past history referred to as exposure) of images.

Thank you for your opinion, but I disagree as described above.

It is difficult for me to place any credibility on your opinions when you use words like "exposure" without defining the definition of it you accept.

From your posts it seems to me you are confused about what exposure and image lightness actually are because you use them together and/or interchangeably when they are two totally different things.

 

[Don Lacy]

Is there any reason why others use manual iso in manual mode instead of auto ?

Because when I am shooting wildlife that is moving I don’t have time to adjust settings to compensate for metering values that are changing which can result in a image is that is to bright with no detail in the highlights if the camera is left to its own devices to select the ISO. Back when I was shooting slides this was called overexposed now I don’t know what it is called since ISO does not affect exposure I guess it’s called over bright.