Iso what does

When the humans leave the office, this group of scrappy video gear springs to life. Their goal? Save marketing from the evilest villain of all Can they do it? Learn more about our company, team, careers, and values. ISO is displayed in a number like this: , , or The ISO is how you can adjust the exposure on your camera. Changing the ISO will brighten or darken your image. Changing your ISO for photography will make your image brighter or make your image darker. Typically, the lower the ISO, the better.

ISO for video is basically the same as it is for photos. And just like with photos, the lower the ISO, the better, because your image quality will be crisp and clear.

Higher ISOs tend to look noisy or grainy. A low ISO is technically going to give you the best image quality possible. If you use an ISO of , and your image is properly exposed, this is the best scenario to be in.

The higher the ISO, the more grain and noise you introduce to your image. That in mind, try to keep your ISO low if possible, and only raise it when you need to! One thing to note when it comes to ISO is that all of this is also relative to your camera. Some cameras are great in high ISOs while others have very noticeable grain.

The aperture will have to increase. And when the aperture increases, more light will be let in. So you may have to lower your ISO just a bit, to not overexpose the image. The goal is to photograph a nighttime football game. How can we adjust the camera settings to capture an image like the one below? Let's go through it step-by-step. Now we have our target qualities in mind, let's go through the settings we need to make them happen.

Both the foreground and the background are mostly in focus. In fact, the football field and the back fence are pretty sharp. This can be achieved with a small aperture and a fairly high ISO. So, in order to get the frozen motion we want, we need a fast shutter speed.

If we wanted to make the image more dramatic by blurring the background, we could open the aperture to create a shallow depth of field. Understanding the exposure triangle and how they all work together is critical to taking consistent high-quality photos and footage.

Playing around with sharpness and blur brings some creativity to your craft. Create robust and customizable shot lists. Upload images to make storyboards and slideshows. Previous Post. Next Post. More Like This More articles like this. Article Collections. Articles like this, right in your inbox. First Name required. Last Name required.

Email required. If it is based upon clipping, noise or grey level Or maybe a home brewn one. For RAW? There are no definitions to begin with. It is just digits that might need extensive massaging to get a useful image.

Using multi segment exposure metering - all goes out the window anyhow. It is some kind of AI algorithm I think. Optimizing the result. Whatever that means. ISO is defined exposure index, so the answer is no. However, as this has been true for photography from almost its beginning, you can actually define a person exposure index based on a particular process or system. It does not make the ISO inaccurate, it just redefines the criteria for a new index.

One reason ETTR is impractical as an exposure index is it measures from the most variable area of scene, the highlights. That does not mean they cannot use multiple variables to achieve that result. An exposure index needs to account for the entire imaging system to the final result. ISO only defines a few criteria. Good to know, thanks. How authoritative is CIPA in practice? Do smartphone cameras follow it, for example? The middle gray method is kind of fishy as it assumes the user wants JPEG.

It also assumes that this in camera JPEG is the final result, that the photographer makes the image fully in the camera. For negative film it was the toe that defined the sensitivity. For positive film it was clipping.

Both are meaningful measures. The "middle-gray" method which is not a method assume that photographic system is to produce an image with tonality in relation to the original scene. That is not "fishy," that is practical. If you have a system that cannot recreate the visual impression of a subject, how do you control the system?

For both negative and positive film, the speed point was used to calculate the ISO value because that point on the toe was less effected by processing. If scene contrast is greater than the recording media, the loss of information in the shadows and highlights less effects where the most visually useful information for the viewer remains. Mid-tones are important for a reason. And lets be clear with film, the ISO is based on both the speed point and contrast.

That is why you can push film. Like a sensor, film has only one sensitivity, but it is the processing and the ISO definition that allows differing exposures for the same material. It might be important to point out that when you photograph a gray scale and color checker, you want the image to reflect your perception of that. ISO is one key aspect of that happening.

There is nothing arbitrary about ISO. That is not an arbitrary number. The methodology for designing an exposure index has gone through a great deal of research and the process is constantly being refined with exposure systems and processing. But what is also implicit in an exposure index is the response of the system, particularly contrast. Technically, any reflectance values could be selected, although each produces a challenge.

This is really why the article is so disappointing, beyond its technical errors. It does not address the fundamentals of what ISO gives photographers and the problems it solves. It is a pity DPreview did not approach experts to write this.

But the processing is not arbitrary it might be unknown to the photographer, but that is very different from arbitrary. Take a photograph of a color checker and see if the results are more constant than different. And use different cameras. You will find the consistency.

Camera manufacturers are not trying to produce system that cannot reproduce what is in front of their products. The digital sensor is, mostly, linear. At low levels the signal to noise ratio becomes low, eventually being too noisy. At high levels it reaches saturation and eventually clip. The useful portion varies between those limits from sensor to sensor. To get a useful image, the tones of the image shall be within that useful portion.

By setting the exposure meter to a high ISO you move the image down into the noise. And by setting the exposure meter to a low ISO you might cause clipping.

This is our technical limitations, if we work with RAW. And, from that technical limitations we can do almost anything we want. And within that freedom, there is no middle gray tone. What you are saying D logH is that the camera manufacturer see the camera as an image system that, from subject, to digital original e. And, how the manufacturer do this is not really interesting for the user. I see the benefits of that view D logH. It is very useful. Most people do not care about the technical details.

Then you have a choice. Expose to the left and get short exposure times or expose to the right and get low noise. And yes D logH, I understand that it then is hard er to get a standardized work flow that accomplish an optimal reproduction of the image. But, I assume you see the value of this approach also. Right, I was about to write a response but you beat me to it and probably in a better way than what I was about to write.

Deciding which part of the raw digital sensor response gets mapped to middle gray is arbitrary to some extent. Our cameras shoot JPEG by default, and there is a number that reflects the overall processing from light to that, but we also have the option to dump an intermediary file that is somehow also affected by that number but in a completely unspecified manner because the effect is an implementation detail.

For those that rely on that intermediary dump in their workflow, that number in its current form is not as useful as it could be. If we look at the saturation-based calculation, it looks to me as though it could very well be applied to RAW values, even though reporting it is forbidden by the standard. It would just have to have a different name. First, I am not arguing against other methodologies.

ISO presents one solution to the problem of making photographs. I would argue that it has been extremely successful. ETTR is another methodology to optimizing exposure. If, for example, minimizing noise is important for a photographer, that is a good methodology.

However, there are other criteria that photographers may have where minimizing noise is not that important. I would imagine ETTR would be a nightmare for documentary or wedding photography. I have also seen successful photography using a method that minimizes exposure. And that is one large problem with technical discussion: are you arguing a technical point or a personal one? And technology is improving constantly. I am not sure under actual viewing conditions that anyone could identify the difference of randomly selected images using different exposure methodologies.

It is the full package, as defined by ISO, and as being used by camera manufacturers. That defines how to map the subject to the image, e. ISO is also a setting for an exposure meter. And if it is an older exposure meter, you can simply set ASA instead, same same.

This is totally camera technology agnostic. There are two not by camera manufacturers used? ISO sensitivity definitions. Based on noise and clipping. Form reading the article and some comments my conclusion is that the ISO setting is not that important in digital photography, would this be correct? Perhaps from another angle; what today, would I not be able to do, if there wasn't an ISO option?

If I may, semantically, light is light - we happened not to "like" the random variation in the light intensity. If we did, we may call it a feature rather than noise and would be trying to exploit it even more. Compared with film, DSLRs already provide a few extra hand-holdable stops thanks to image stabilization. Depending on how it is implemented in your camera, setting it to Auto ISO may be even more practical. If one is limited by the exposure DOF, motion blur , then there is no disadvantage in increasing camera ISO setting to the brightness that is acceptable no blown high lights, for example.

Me, exposure bracket is my friend. Now, is there ISO bracketing?? As long as I have the desired DOF from the aperture and the "correct" shutter speed to freeze or allow motion blur then the camera can do what ever arbitrary brightening it likes.

I adjust it in post anyway. You may still want to set the maximum auto ISO setting to where your camera becomes more or less ISO-invariant, to reduce the chance of highlights being clipped.

My camera allows 3 user-defined auto ISO settings. The main one I've used is capped at ISO As for clipping highlights, that's what the histogram is for. If your highlights are clipping it means that you're letting too much light in and you need to change either the aperture or shutter speed or bracket separately for shadows and highlights.

The "exposure triangle" for digital camera's should be: Aperture, Shutter Speed, Histogram :. From that day on, I set it to max on auto, but even that annoyed me, so I went for maximum quality ISO at all times, and now mostly forget about it, just like in the days of film.

I won't allow my camera to use inferior noisy ISO values without my agreement! But those "noisy" iso values are only noisy because you have reduced the shutter speed or aperture. If you give the sensor enough light then it's not noisy. One day I'm going to have to do a test where I shoot the correct aperture and shutter speed for a sunny day but set the ISO at some ridiculous value and then see in raw if it makes a difference.

If you're a jpeg shooter, however, I would agree with. The price to be paid for this improvement is in the highlights: vertical lines move to the left 1 EV every time the ISO is doubled dynamic range is reduced 1 EV in the highlights.

Thanks for the bed time reading : I hadn't considered the well depth at different iso's. Still testing it in the morning ;. Well capacity does not change. It's a physical property of the sensor. What happens at higher analog amplifications is that everything over a less than full well value is recorded at the highest digital value and thus clipped. Right, slight abuse of language on my part. But the end result, with the system taken as a whole, is the same. I over exposed a shot at iso by 2 stops ie with aperture and shutter speed appropriate for iso Jpeg had good shadow detail with little noise but the highlights looked clipped as expected.

With the raw, I was able to recover all the detail from the highlights I expected to recover some of the detail but didn't expect to recover all of it. This is the opposite to how many say we should shoot ie underexposing to protect the highlights and then bringing up the shadows and the noise with it. Still need to a proper test and work out what all of this means but it would appear that regardless of the lower "full well" values at higher iso's, it's still more than enough to retain 2 stops of highlight detail at least in raw of this one test.

I mean that the raw files were never clipped in the first place. The jpeg highlights were clipped, the histogram indicated that they were clipped though the histo is based on the jpeg output so that's expected but there was plenty of info in the raw file to drag the exposure slider back and have a correctly exposed image.

What I'm trying to say is that in real world shooting situations AND IF YOU SHOOT RAW caps for emphasis not shouting then you likely don't have to worry too much about clipping highlights at higher iso upto because the "well depth" though reduced compared to base iso is still sufficient to retain that info I think we are trying to say the same thing but coming at it from different angles so it looks like we are disagreeing.

While ISO may have enough saturation capacity, lower ISO settings may have even more ; for example, on your X-Pro2, ISO would have one additional stop of highlight headroom, and essentially the same noise floor.

A response in the true spirit of the pedantic nonsense that usually accompanies such discussions. I am known for regarding exposure as trivial, and ISO doesn't even deserve a mention. For most users, considering ISO as "turning up the volume" is a pretty good model. Some people want to know what ISO really means, others do not care. Both ways are perfectly reasonable. Comments about whether people should be interested or not are completely pointless.

Snapper - it makes a molecule of water. Snapper Well, to be even more pedantic and in the spirit of correcting what really is not in need of correction anyway :.

But I digress. It's actually composed of a hydrogen atom with a weak bond to an oxygen atom with a stronger bond to another hydrogen atom forming a hydroxide. Contrary to all of the popular internet memes, water is not Dihydrogen-monoxide, it is Hydrogen-hydroxide.

How about: "If the image is going to be underexposed, increase the ISO, but note that noise may become more apparent". Underexposed relative to what? Do it if you want a pleasing JPEG result. I refuse to use that ridiculous "blightenous" word. Now, it explains even less than before. Wow, I am not the only person still commenting!

I somewhat disagree. The shot noise is baked in once the shutter closes and can neither be increased nor decreased by the ISO setting, it can only be rendered more or less apparent. There may be some other sense in which noise can be less at higher ISO. If the new standard is only sRGB jpegs, what does this mean for people like me? Nothing has changed, in that respect. If you've already found the optimal Raw settings and exposure strategy for your camera, you should stick with it.

If you are using a raw workflow, your exposure management is best not conducted according to ISO ratings anyway. If you do so, you're probably leaving a lot of your camera's potential performance on the table as it were. Simple enough to do your own tests, or to use sites like Photons to Photos or DxOmark, if you are really concerned.

The question really is, how much trouble you want to put into optimising. The standard does not impact you at all. ISO is an exposure index. Whether you shoot images with a greater bit depth than 8-bit or use a different color space, that will not have any significant impact on the index. The reason for the sRGB jpeg criteria is so manufacturers have a consistent environment to work in.

And yet so many do not understand it. I keep seeing people stating that "ISO is part of the exposure triangle" for example. So it would seem that this "old news" is yet to be new news to many. ISO or speed rating as the ISO standards call it is indeed part of the exposure triangle, whether you like it or not. Exposure is scene luminance filtered by aperture, filtered by shutter speed. ISO is a standard for translating exposure to image lightness. It's not part of the exposure triangle, whether you like it or not.

As for the 'exposure triangle', you are right, ISO is part of it. The question really is how useful is the triangle as a teaching aid, and, I suppose, whether peterson's original name, 'the photographic triangle' would be less misleading. And the question is not how useful the exposure triangle is as a teaching aid. It is not a teaching aid - it is a simple fact, which existed long before Peterson renamed it the photographic triangle.

Make of it what you will. The "exposure triangle" ignoring the geometric attributes is short hand for the "Auto exposure triangle" but many forgot the "Auto" part and the fun ensued. And for the really older folks, it was called "needle and match exposure triangle" ;-.

Well, I guess that answers that then! The "exposure triangle" is not really a triangle at all. It's always been a poor analogy. If you lengthen one side of a triangle to twice its length and reduce another side to half its original length, you do not have the same area within the three lines that constitute the triangle.

ISO is simply an exposure index. The author clearly does not know that negatives are processed to a particular contrast index to match the printing media response. I give DPreview 10 out of 10 for trying to educate its audience.

However, this article has no real value. But what is 'the aperture and shutter speed required for a particular light level'? Think on that one, and you'll realise that your argument is circular, because the only thing that determines the EV f-number and exposure time 'required' for a particular light level is the ISO setting.

Think about it and re-read and you might find that the article has real value for you. I understand an exposure index. I also understand how it works. The article is just confused and does not really understand the underlying photographic process the ISO is trying to address.

You might have gotten a clearer explanation by just sticking to digital cameras, rather then misrepresenting film processes. However, you are confusing metering accuracy with ISO values--a more accurate metering system that can compensate for a particular image system does not imply the ISO value is arbitrary. And manufacturers, both film and digital, have always been able to "decide what the image looks like.

The exposure index specifies the exposure that the camera's metering system should aim for. The exposure index for most cameras will be the specified ISO value modified by the specified exposure compensation. The default metering mode for most cameras is called something like "matrix metering," which ignores the exposure index and uses heuristics to derive an exposure that will hopefully be appropriate for the scene being photographed.

Richard Butler decided not to write about metering, and just talk about ISO as a measure of camera sensitivity to light. This means he cannot, for example, explain why REI exists, but I do understand his desire to limit the scope of the article to something manageable.

EV is agnostic of the amount of light in the scene. I used EV 5. This is true regardless of how bright the scene is. My image of the coal mine may be totally black and my image of the beach might be totally white, but the exposure value used to capture both scenes was EV5. In any camera review I have seen in the past years on this website, there has always been a comparison with competing cameras, especially in a studio scene.

There the results were always compared at the same nominal ISO setting, ignoring the exposure settings. Given the background information you are giving us here, is this approach in your reviews still applicable?

I mean, shouldn't you rather compare the results of different cameras at the same exposure settings, instead at the same ISO setting? Probably best to clarify, you test at the same exposures, not the same exposure settings - as I understand it the lighting can change so the settings can change to normalise exposure. Maybe you can one day write an article about how you perform the tests. This could be interesting for us as well.

This article covers the basics of the main test scene, if you've not seen it before. So essentially, ISO is the sensing medium's 'exposure speed'. It makes sense considering that we have shutter speed and lens speed aperture as other controls for exposure. The sensor or film can only capture the photos falling on it and everything else is processed both film and digital to approximate the middle gray. You're right, the sensor can only try to count as many photons as the aperture and shutter speed give it.

It can't magically come up with more photons to count all by itself. Since ISO doesn't say anything about what has to happen to the Raw file, your 'safe conclusion' is essentially 'I'm sure the camera engineers will provide something usable. All three of those will give you the same image lightness, but one of the three will look significantly worse than the others.

There's a good reason to treat ISO as a secondary function, rather than a core exposure element, regardless of whether you're interested in physics. Surely "ISO is a representation of the net system response including all processing " just means "effective sensitivity" or "speed rating". Why the need for pseudo-scientific gobbledygook? Richard "Since ISO doesn't say anything about what has to happen to the Raw file, your 'safe conclusion' is essentially 'I'm sure the camera engineers will provide something usable.

HEIF as well? Raw is a thornier problem. Until you process it ie: impose a torn curve on it , then there isn't a specific value that corresponds to middle grey. In principle, you could create a standard like the methodology DxOMark uses, measuring the saturation point of the Raw file then picking an arbitrary value below that to represent middle grey, at which point you could assign some sort of value to the Raw response.