Got

Noise?

Here is a question for you. Have you ever taken the time to look at the actual file size of your images? I am not talking about the pixel dimensions, but the megabytes. If not, do it. You might be surprised that the numbers are all over the place. It doesn’t matter that you’re shooting with the same camera, or that the images are all from the same day, or even the same shoot. Chances are, you will find quite a bit of variability in the amount of information contained inside each individual photograph.

One image might be 100mb. The next, 81mb. The following, 20mb. The maximum file size that you can capture with your images is, of course, dictated by the resolution of your camera. Naturally a 50-megapixel camera will have larger files than a 16-megapixel camera.

But sometimes it doesn’t.

So, why, if you are shooting with a 50-megapixel sensor in your camera, are you bringing home images that are sometimes the same size or less than those from your old 16-megapixel camera?

The answer to this lies in the thing that your camera’s sensor was designed to capture: light.

In digital photography, light is information.

Your camera is not capturing the life force of an animal, it is capturing the light reflecting off that animal.

Recording light is the primary job of our imaging sensors. The more light you have, the more information you have, the larger the file size you have to work with. Likewise, the less light you have, the less information you have, the smaller the file sizes.

But none of this has anything to do with the amount of available light you had to work with when creating the photograph.  The fact that the sky was overcast or sunny, or it was dawn, or noon, or an hour after sunset is completely irrelevant to all of this. Instead, it’s about the amount of light you ALLOWED your camera to capture.

You see, all of this is a choice – whether you realize it or not at first. You make a choice every time you trip your camera’s shutter as to how much information you are going to record and therefore how big and clean your files are. Which, by the way, bigger file sizes are better.

This choice comes in the form of your exposure. How large or small is your aperture? How high is your ISO? What about your shutter speed? All these things come together to dictate how much light your camera’s sensor will record.

So, if we can agree that more information is better, why would you make the conscious decision NOT to capture the biggest and most information packed files possible? Why would you consciously degrade your photographs in the field?

Let’s take this a step further though.

Whereas light equals information, the lack of information equals noise in our photographs. Technically, there is much more to this whole noise thing. But if I can be honest here, that only confuses things. Let’s keep this as simple as possible.

So, here you go one more time. . .

Noise = a lack of information.

Noise can look like graininess in the image, or it can look like a neon colored Jackson Pollock painting with splatters of green and magenta in the shadows. Photographers lose sleep over this stuff. They spend extra money on specialized plugins and programs to help them remove noise when they process their photos. They talk about it at dinner tables, complain about it in the field, and many wrongly assume that they can NEVER use their camera above some magical ISO limit because the noise becomes unbearable to them.

So, this makes me wonder: if us wildlife photographers feel like we are constantly fighting to create images with as little noise as possible, why would we choose to set our cameras up to create images that are full of noise? Especially when we could take the same photograph, in the same available light, with significantly less noise, and all while using ISO settings upwards of 20,000 or more . . .

Small file sizes and excess noise are the consequences of not recording enough light in our photographs. This is completely avoidable. It is completely unnecessary. And all our cameras come with a built-in tool that when used correctly, will dramatically increase the size, quality, and lessen the noise in our photographs.

This tool is the histogram.

For those of you who have joined me in the field on a workshop, there is a pretty good chance you have heard me say that I firmly believe the addition of the histogram is the most important thing to come out of the digital revolution in photography. It’s not the fact that we can see a photo on the back of our cameras. It’s not that we can format memory cards and start all over again (although this is really nice). It’s the histogram. It is our ability to read exactly how much information is being recorded across 255 different tones of light and adjust our exposure accordingly to guarantee that we have captured a photograph with a perfect exposure every time.

But what exactly is a perfect exposure?

Believe it or not, this definition has shifted with the evolution of the technology in our hands.

Back in the days of color film and slides, a perfect exposure was between 1/3rd and 2/3rds of a stop underexposed for our mid-tones. Why? It was about color richness. Underexposing in camera helped to saturate colors. In fact, Nikon purposefully built their metering systems to always underexpose slightly in order to create richer colors – which is why there is a difference in the metering system between companies like Nikon and Canon.

That was then. This is now.

And now, EVERYTHING is different.

Uncompromising quality. Workshop level education. The Art & Science of wildlife photography at your finger tips.

This photograph of a cinnamon colored black bear cub was created at 10,000 ISO. Forests are notorious for low light and forcing us to use high ISO settings. When setting my exposure for this composition, I pushed the information on the histogram as far to the right as possible, just to the point of beginning to “blow out” or “clip” the highlights around the bear’s where the sun is rim lighting. This ensured that I was capturing the maximum amount of information without losing detail in the bear cub.

In the digital world, the popular misconception is that a good exposure is one that does not “blow out the highlights.” To be fair, there is a whole lot of truth in this. But the problem with this definition is that it leaves everything up to interpretation. To suggest that as long as we don’t blow out our highlights we have captured a perfect exposure, opens up a wide range of possibilities that are absolutely not correct.

Just because you are not blowing out your highlights doesn’t mean that being 3 stops underexposed is OK. In fact, it’s quite the opposite. This is exactly how we end up with noisy photographs.

Photography is a form of visual art. And with art, it is damn near impossible for anyone to tell you there is a right and wrong way of doing something. But when it comes to exposure, with digital technology, there absolutely is a right way to do it.

All the creative vision, the artistry, the subjective opinions, and artistic interpretation is exactly what we should strive for as photographers. But when it comes to capturing the biggest, cleanest, and sexiest file you possible can, one that will hold up to ruthless editing in Lightroom and Photoshop, and comes out smelling like a rose on the other side, you have to understand that there very much is a right and a wrong way of doing things. And that is because of how our cameras record information.

Of all the 255 different tones of light that your camera’s sensor is capable of seeing and capturing, it does not record information evenly or equally across these different tones.

If light equals information, then the lack of light equals a lack of information. We have established this already. But what this means is that brighter tones of light contain more information for your camera to work with than darker tones. Darker tones, on the other hand, are places with a lack of light and this is why we tend to see noise in shadows first.

In other words, the brighter the photograph, the more information that is captured with the image.

Conversely, the darker the photograph, or maybe we should say, the more underexposed that it is, the less information that is recorded.

This is where sayings like “expose to the right” come from. It’s something of a mantra that we all repeat to ourselves in our heads. Most photographers have heard this, and they even know that it is something they are supposed to do. However, many photographers I see on workshops do not actually understand what this really means and how crucially important it all is.

To understand how to overcome noise in our photographs, to learn how we can shoot with ISO settings upwards of 25,600, we must first understand EXACTLY what our histograms are telling us. And if you remember from the first installment of this series of articles, your histogram is a display of how information is being recorded across 255 different tones of light. . .

Let’s be honest here. If you were to try and judge your exposure based upon 255 individual tones of light, your brain would probably melt from trying to make sense of it all. Camera manufacturers know this and so they simplified things down a bit by dividing your histogram into 5ths.

Take a look at your camera’s histogram and you will find that it is divided up into 5 separate columns, with each column basically representing 1 full stop of light in your exposure.

Disclaimer: some cameras may only have 4 columns here. In fact, what is often referred to as “consumer” level cameras are this way as well as older models. If this is you, then you will have to adapt what I’m going to say here to your specific camera. For the rest of this Got Noise series, however, I am going to universally refer to histograms as being divided up into 5 columns because this is how the vast majority of modern cameras are engineered.

With that out of the way, let’s get back to our show.

Stops of light are measured logarithmically. This means that when you increase your exposure by a full stop of light, you are actually doubling the amount of light that you recorded. Likewise, if you reduce your exposure by a full stop of light, you are halving the amount that comes in.

Let’s say your shutter speed is 1/30th of a second. If you were to speed up your shutter to 1/60th of a second, reducing the exposure by 1 full stop of light, you would effectively halve the amount of light that is coming into your camera because the shutter is open for exactly half the amount of time. The same goes for your ISO as well. An ISO setting of 100 is a full stop different than ISO 200, which is a full stop different from ISO 400.

When it comes to your f-stop however, the numbering system is a little different because of the way in which an f/stop is measured. You would think that f/8 is one stop different from f/4, but it’s not. Instead, f/5.6 is actually one stop less light than f/4. The reason for this difference is the fact that f/stops are based on the inverse square law.

I can only image the glazed looks I am getting at this very moment, so I will make this fast and simple. A full stop of light change in f/stop is its based upon multiplying or dividing the number by the square root of 2, which is 1.41. So, going from f/4 to f/5.6 is a decrease in one full stop because 4 x 1.41 = 5.6.

Did you survive?

Good. Let’s get back to histograms.

Now that we understand that changing our exposure by a full stop of light is really about doubling of halving the amount of light that is being recorded, we can begin to understand how that our cameras record information logarithmically across the various tones of light.

If light equals information, and we open up our exposure by one full stop, which effectively doubles the amount of light, then we are also DOUBLING the amount of information that our camera is recording.

Because of this doubling effect and the logarithmic nature of light and exposure, a full 50% of the information that your camera is capable of recording can only be captured in that last column to the far right on your histogram.

Let’s pause here for a second and restate this part for emphasis, because it’s that important. . .

A full 50% of the information your camera is capable of recording all happens in the last column on the far-right side of your histogram.

50%!!!

This means that if we take a hypothetical exposure where the histogram stops right at the line where that last column begins, we are only recording 50% or less of the information that our cameras are capable of recording.

This means that if we take a hypothetical exposure where the histogram stops right at the line where that last column begins, we are only recording 50% or less of the information that our cameras are capable of recording.

If your histogram is underexposed to the point in which the information stops at the second to the last column, then you are only recording 25% of the information you can.

Let this sink in for a moment.

Every photographer on the planet has at some point and time created photographs where the histogram stopped one or even two columns short of being all the way to the right side of the graph. They looked at the photo on the LCD, thought it looked good, and kept on shooting.

Everyone has done this, pros and amateurs alike, me included. And with each of those photographs, we came home with only half the amount of information (or less) then we could have otherwise, unnecessarily degrading the quality of our images, and creating excess noise that then has to be dealt with later.

If you want to know where all that noise is coming from in your photographs, then look no further than your histogram.

It’s likely that until now, you have been told that noise comes from using high ISO settings and not sloppy exposures. There is some truth to this, of course. The higher the ISO, the more noise you will introduce to the photograph. But the amount of noise that is actually introduced is much less than you think as long as you are capturing the maximum amount of information your camera is capable of in a given situation. And unfortunately the assumption that ISO is the cause of all noise in photographs is used as a crutch for even sloppier exposures and therefore creating even more noise.

In all fairness, we find a wide range of ability in cameras to handle high ISOs in low light. The age of the camera plays a role in this. As does the number of megapixels in that camera. But if you are using a modern camera then chances are it will at least handle up to 20,000 ISO. It’s just that you have to be absolutely obsessive about pushing your exposure as far to the right as you possibly can.

In fact, you should push it so far to the right that you actually begin to blow out or clip your highlights, and then bring it back 1/3rd of a stop.

One of the challenges in teaching photography is that oftentimes photographers come to the table with a proverbial cup that is already full. It’s full of assumptions. It’s full of bad habits and misunderstandings. And worst of all, it’s full of bad information gathered over time from other photographers – especially those at the local camera club.

The two biggest obstacles that often need to be hurdled before you can accept this cold hard fact about light and how our cameras record it, is accepting that the photo on the back of the camera is not, and will never be, a reliable guide by which to judge your exposure AND that there is no such thing as a proper SHAPE to a histogram.

Let’s start with the image on the back of your camera.

First, understand that this is nothing more than a low-res jpeg image you are viewing. This means that it does not contain all of the nuances of light that will be in the final image, nor does it have the ability to depict all the tones of light you captured. The dynamic range you see does not accurately show what you captured in raw format.

Secondly, how you perceive that image on your LCD is directly related to the light in which you are viewing it. If you are looking at the LCD on a bright day, then your image will look dark. If you are looking at your image through the electronic viewfinder of a mirrorless camera, your camera will typically adjust the brightness of that image to the ambient light. Additionally, the brightness of the playback image on both the LCD and viewfinder are customizable which means they are not realistic representations of what you recorded.

Even at ISO 7200, there is very little noise in this photograph. The second photograph shows part of the original unedited raw file along with the corresponding histogram so you can see the degree of noise in the background and shadows.

Technically speaking, I could have gotten away with increasing the ISO on this photograph even more without any problem. As shot, I likely underexposed the image by 2/3rds of a stop and what little bit of noise that is seen in the background is the result of that.

Looking at the histogram, you can see I only recorded 30-40% of the information my camera is capable of recording. And this is why there is still some noise in the background.

As for the final image that is displayed first, you can see that when we expose to the right such as this, it’s often neccesarry to reduce the exposure or mid-tones down just a bit to bring back a more natural looking dynamic range and contrast to the photograph. This, with just a touch of saturation was all that was needed for post-processing.

How we perceive color and tones of light is directly related to the ambient light we are viewing them in.

So what good is the image on the back of your camera if not for looking at your exposure? The playback image serves two purposes. It lets you study your composition and it allows you to zoom in to check your focusing. THAT’S IT!

The second obstacle, the whole shape of the histogram thing, tends to be one of those awful myths that the wildlife photography community still struggles to shake. Most people learn this from other photographers. Or, worse yet, from their local camera club. Or, even worse, a camera store.

The assumption here is that a perfect histogram should be in the shape of a bell-curve with the peak in the middle slowly tapering off to black and white. Heard this one before? Are you a bell-curve kind of person? If so, get over it. It is flat wrong and one of the stupidest bits of misinformation to make its way into the collective conscious of photographers.

The shape of the histogram is completely 100%, dependent upon the light reflecting off all the stuff in your composition. If you are shooting a silhouette, for instance, where you have a black subject (silhouette, duh) with beautiful colored light all around it, you are going to have a histogram that looks like an American football goal post instead of a bell-curve. Why? You will be recording lots of information in your shadows (the spike to the left) and lots of information in your highlights (the spike to the right) and very little information across your mid-tones (the stuff in across the middle).

Part of the problem here comes from misunderstanding what spikes in their histograms actually mean. You see, there is nothing wrong with a spike. Or two spikes. Or 20 spikes for that matter. Recall that a histogram is ultimately a reading of the 255 different tones of light that the camera can record information across. A spike in the histogram simply means that the camera is recording a lot of information in that particular tone of light. Maybe that’s in the middle (mid-tone), maybe it’s near the left (shadows). It doesn’t matter. Spikes in the histogram only mean that lots of information is being recorded in that particular tone of light.

If we were to capture a perfect bell-curve on the histogram, this would mean that we captured MOST of the information along the mid-tones and little to none in the highlights and shadows. This doesn’t happen very often. You can at times find it in flat overcast light if, for instance, you point your camera straight down at the grass when there are no shadows or highlights AND you set your camera’s exposure to 0 on the light meter. This will give you a bell-curve. But this is not 99.999% of the lighting situations we encounter and therefore it is also never going to be 99.999% of the histograms we see either. If you see a bell-curve in your histogram, rest assured that you have the world’s flattest and most boring light.

Knowing that there is, first and foremost, no such thing as a proper shape to a histogram, and that a perfect exposure IN DIGITAL PHOTOGRAPHY is one in which the histogram is as far as possible to the right without blowing out highlights, then we can now utilize the most important tool at our disposal in our cameras.

And by merely glancing at the histogram we can know so many things.

  1. We can judge what our exposure really is.

  2. We can make calculated decisions to decrease the noise in our photographs and increase the resolution and information captured in each photograph.

  3. And maybe best of all, we can tell in an instant exactly what we need to do to correct the exposure.

The first two points above should by now all make sense. The last part may not be so obvious. However, if you remember that each column on the histogram equates to roughly one full stop of light, then you can always make a quick and dirty judgment call as to how much more light you need to add to the exposure.

Our cameras are set to adjust exposure variables (shutter speed / ISO / aperture) in 1/3rd increments. So, all you have to do is visualize each one of those columns on the histogram as being broken up into 3rds. Knowing that each column is one full stop, you can make a judgment call as to whether or not you need to adjust the exposure by 1 full stoop, 1 and 1/3rd stops, or just 1/3rd of a stop to push your exposure as far to the right as possible.

All of this seems simple enough right? Push the exposure as far to the right on your histogram as possible in order to reduce noise and give you the biggest files possible to work with. Cut and dry. Well, almost. There is a catch. When we expose to the right, and I mean really expose to the right, our images are going to look washed out. Colors will be awful. Shadows will be awful.

Expletives will tumble from your mouth followed by my name. It’s OK. I’m used to it.

But, as long as you have not overexposed in the literal sense of the phrase by blowing out your highlights or whites, then all of the information you need for the photograph is there. The key here is to understand that in digital photography, processing your images is now 50% of the game.

Ansel Adams famously explained that his photographs were created in the darkroom. He likened what was captured in camera to a set of ingredients that he could then work with later. Today, so many decades later, with such incredible leaps forward in technology, nothing has changed. If you pick up a copy of National Geographic that was published in 1981 and lay it side by side with this month’s issue, the difference you see in the quality of the photographs largely has to do with the invention of digital photography and the use of editing software like Photoshop and Lightroom.

By exposing to the right, you have ensured that you captured as much information in the most forgiving tones of light possible. Once images have been downloaded and opened in PS or LR, you can then simply recreate the dynamic range you either remember or see in your creative mind’s eye.

To do this, we simply reduce the exposure a bit on the computer and adjust the black and shadow sliders. All of this is done in your raw processor – which means either Lightroom or Adobe Camera Raw if you only use Photoshop. Dropping down the exposure or darkening the image in PS / LR is simply a matter of removing some information. You can take away information all day long. What you cannot do however, is add information (light) without degrading the image to some degree by adding noise.

Whereas noise is created in the field by not capturing enough information, in Photoshop / Lightroom, or whatever your preferred post-processing software may be, it is created by trying to artificially add light by brightening our images.

So, the moral to the story is this: If you got noise, check your exposures. Noise is for all intents and purposes, created by a lack of information. More light equals more information. More information equals less noise.

Understand this, and you wont need software like Topaz to remove noise for you.

There is nothing about this that is intuitive. It is the polar opposite idea compared to film days. However, it is the right way to do things with digital photography. Understanding the nuances of the technology in your hands allows you to step up your photography game. It allows you to take control of noise in your photographs, to produce the largest files possible for your camera, and it gives you so much more latitude for processing your images on the computer. All of which is a good thing!

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