While there is some technical merit to those statements, the end result of choosing a higher ISO sensitivity is that there will be more noise in your photograph. This is not always a bad thing, though. The resulting amplification of light allows for a higher shutter speed or a smaller aperture – either of which may be necessary to execute a successful shot.

Here is a simple test to show you how these effects play out.  All of these shots were done on a Canon EOS Rebel t1i. The point here is to show how much noise is generated with this camera as the ISO sensitivity increases and the overall exposure is held constant.

To perform the test, I mounted the camera on a tripod and used the EOS Capture Utility to remotely trigger the shutter and alter the settings. I used my Canon EOS Rebel t1i with a Canon 85mm f/1.8 lens attached.

I started with ISO 100, and selected what seemed like a “proper exposure” – 1 second at f/5.6. Then, I held the aperture constant (so as not to effect the focus of the image), and as I increased the ISO by one stop I simultaneously decreased the shutter speed by a full stop. So at ISO 200, the shutter speed was 1/2 second. At ISO 400, the shutter speed was 1/4 second. So on and so forth.

To properly appreciate the results, click on the grid image to see it at full size. Each of those squares is a small sampling of the original image above – zoomed in to about 75% of actual size. Certainly there is some room here for perceptual differences, but I see no discernable difference between ISO 100 and 200, a slight amount of noise/speckling at 400, and the first significant amounts of noise at ISO 800. However, it is still quite understated at ISO 800. By ISO 1600, the noise is quite clear and at ISO 3200 it is more pronounced.

A few interesting points, however. First, take a look at the original image at the top of this post. That is the ISO 3200 image. Downsized to 625 pixels high, there is almost no perceptible noise. You have to view the image at a fairly high resolution (25-50% of original size) to appreciate the noise. If you’re viewing the images on the web, you’ll rarely look at an image that big. This will only make a difference if you’re using an uncropped image to make a very large print, or if you’re using a cropped image in a smaller print.

This also doesn’t taken into account the awesome noise reduction possibilities in Adobe Lightroom or Photoshop. Lightroom does an excellent job at noise reduction, although very high levels (50+) will lead to a significant softening of the overall image.

Also, the reason that I specified the camera being used (a Canon t1i) is that noise is a function of the image sensor and processor. Larger sensors with better processors (i.e. a Canon 5d MK II) will handle noise significantly better and allow for higher ISO shots with less noise.

Clearly, choosing a higher ISO rating than necessary leads to extra noise. However, if the image is still properly exposed, that noise may not be very apparent in most cases. The problem only becomes very pronounced when the resulting image is still underexposed, and the exposure is raised in post production. But this will be an example for another day.

In general, it’s better to choose an ISO setting that is at or slightly above your needs. In everyday shooting, I typically choose an ISO rating of 400 to 800, because I know this will give me more room to play with the shutter speed / aperture, and I know it won’t adversely effect the image. Moreover, I’ll happily switch to ISO 3200 if its necessary to get the proper shutter speed – i.e. basketball games, wrestling, or an indoor fashion show with no flash.

When you leave the camera in an automatic or semi-automatic mode (i.e. Automatic, Aperture Priority, Shutter Speed Priority), you let the camera pick some or all of the settings that determine an image’s exposure. The camera has a built in light-meter, and it makes an educated guess as to how bright or dark the image should be.

Sometimes… the camera doesn’t know what you want, and it makes the wrong guess. Exposure compensation helps you adjust that guess without going to a full manual mode. If you set it to +1, you’re telling the camera, “Take your best guess, and then make everything a little brighter.” If you set it to -1, you’re telling the camera, “Take your best guess, and then make everything a little darker.”

Take a look at the picture above. This is a perfect example of when you might want to use exposure compensation.

There are two distinct parts of the photo – the brick wall in the foreground and the blue sky in the background. The sun is coming down towards the camera, which means the brick walls are somewhat shaded. You’ve got a choice to make – expose for the brick walls so they come out nice, and your sky will be totally white and blown out. Expose for the sky, and your brick walls will be underexposed and fairly dark.

Given the fact that the brick wall takes up the bulk of the picture, your camera will probably meter for the walls and let the sky blow out. Maybe you agree with that choice. But, what if you want some definition in the sky, and you’re willing to either a) lose exposure on the brick walls or, b) edit it later to make it look better?

Solution: Use exposure compensation and set it to -1 or -2. If you set it at minus one, that tells the camera to make a best guess about the exposure, and then make the image one stop darker. Likewise, minus two tells the camera to make the image two stops darker.

The camera will make the necessary adjustments, and you end up with an image like the one above – the foreground is relatively underexposed but the background is ok. That’s the choice I made and later cleaned up with some editing in Lightroom.

The key thing to remember is that your camera will usually expose for the dominant part of the picture. If you have a bright sky as a background and a person taking up a small part of the image, the camera will probably meter for the sky leaving the person underexposed. Shooting into the sun, if you want the subject to be bright, it helps to use some positive exposure compensation (+1 or +2) to make sure that the subject comes out.

It can be hard to predict exactly what the camera will do, though. If you zoom in or out some, that can change the way the camera decides to meter. If you’re using exposure compensation, be sure to chimp your pictures. It also helps to take a picture first, see how the camera metered it, and then decide if you want to compensate up or down. This obviously doesn’t work for action shots, but if you can take a minute to compose your pictures this will work.

If you know you want to overexpose or underexpose your pictures, and you’ve got a constant light source, then you might be better off switching into full manual mode. Then you can determine a shutter speed / aperture that will give you the right exposure, no matter how the camera would meter based on the balance of background and foreground. Although then you run into the problem of a changing light source (i.e. a cloud passing by the sun)…

I had two new students taking pictures at graduation. That tends to happen every year, because my photography crew is all seniors… so they can’t really take pictures when they’re in the graduation. I’m also participating in the graduation, so I can give the new girls some hints here and there but I can’t follow them around and make sure everything goes smoothly.

In this case, I instructed them to try and shoot from the left side of the field, where the sun would come down and light everyone nicely (see post 1 of this series). Then I made the mistake of telling them that if they really needed to take a picture from the right side of the field, they could try putting the speedlight on top and seeing if that helped.

So What Went Wrong?

When I gave the new girls some pointers and we got set up, I put the camera in aperture priority mode. This usually works fairly well for outdoor events. The exposure varied quite a bit, between direct sunlight and shaded areas, so this was a good way to let the camera do the hard work for them. In most of those early shots, the shutter speed ranged from 1/2500 to 1/1000.

What’s the problem? You can’t take a picture with a speedlight and a shutter speed of 1/2500th of a second. The reasons for that seem like a good topic for another post, but the short version is that there’s a max sync speed for your camera and flash. A faster shutter speed just won’t work (unless the flash is in a special low-power, hi-speed mode).

In the case of my camera and flash, they automatically prevent the camera from using a higher shutter speed. The result was that the camera stayed in aperture priority mode, but the camera wouldn’t allow the shutter speed to go over 1/200th of a second. In broad daylight, you end up with a decent amount of blown out highlights at f/5.6, 1/200, ISO 400. See the tops of the caps in the first picture? Pure white…

Perhaps the good thing is that the flash was still doing its job. There was a decent balance between the background and the subject, the only problem was that the background was over-exposed so the foreground was also over-exposed. I managed to save the pictures and make them useable with some work in Lightroom…

But a much better solution would have been for them to switch to shutter-priority mode. By using shutter priority mode, you can set the shutter speed at the max sync speed of your flash unit. Then, the camera will adjust the aperture instead and nail down a (hopefully accurate) exposure. Finally, the flash’s e-TTL system will then light up your subjects. The end result should be a nicely exposed image that doesn’t need to be doctored up after the fact.

In case you have a similar problem and you’re trying to fix it in Lightroom, I found that it worked out fairly well to drag the exposure down a little bit (-0.41 in this case), add some recovery to pull out a few blown out highlights (25 in this case), and then crank up the black clipping until there was a decent level of contrast (44 in this case). In some of the other pictures, I fiddled with the tone curve to add some contrast, too, but I guess I didn’t on this one.

Problems to Consider

There are a couple of problems we have to deal with, and they all deal with varying levels of light.

First, there’s the problem of whether or not the sun is lighting the subject from the front of the back. As we saw earlier, it’s generally better to shoot a subject with the sun lighting them from the frontal arc, but that’s not always possible.

If you do have to shoot into the sun, the exposure is radically different. This image to the left, with the sun lighting the subject, was shot at f/5.6, 1/2500, ISO 400.

A photo taken from the opposite side, with the sun behind the subject, metered at f/5.6 1/1000, ISO 400. The difference here is the slower shutter – necessary to allow the subject to be exposed while shaded from the sun.

Even with the slower shutter, the subject still isn’t fully exposed. To bring her up to full exposure, the shutter speed should probably be closer to 1/500. If you’re moving back and forth from one place to another, and you’ll have to shoot both into the sun and out of the sun, either you or your camera will need to adjust for that.

The second problem is that the lighting conditions can change. If a thick cloud moves over head and blocks the sun, the entire scene will fall into shade. This would bring the exposure of the scene down several stops. It could also be that a thin cloud partially covers the sun, bringing the exposure down just a little bit. So, again, either you or your camera will have to make adjustments for that.

Use Aperture Priority Mode

So what’s the best camera mode to use to make these adjustments?

I do a lot of shooting in manual, but this only works well if you have fairly predictable lighting conditions. Inside, that’s cool. Outside, on an overcast day, that can work too. On a sunny day with changing lighting conditions, this isn’t always the best idea. If the lighting conditions change and I don’t make the adjustment properly, then I risk missing the shot.

Shutter priority? Eh… It’s possible. But, there can be some pretty wide fluctuations in exposure. If you pick too high of a shutter speed, your lens might not be able to open up wide enough to compensate. If you pick a low shutter speed, on the other hand, you might end up with an aperture of f/22. Not necessarily a bad thing, but who knows if you want that much depth of field.

I prefer aperture priority. First, I set the ISO and aperture at a setting that gives me a quick shutter speed in direct sunlight – something like 1/2000th of a second. Then, if I can find a shady spot, I take a picture in the shade and make sure that the shutter speed is still acceptable – 1/125th of 1/250th. If the shade yields too slow of a shutter, I adjust the ISO/aperture.  Something like f/5.6 / ISO 400 or f/4.0 / ISO 200 usually works out ok.

The shutter speed will then fluctuate somewhere between those two extremes – but I’m always confident that it can fluctuate without causing a problem (like motion blur from a slow shutter).

What Next?

So far, we’ve talked about using the sun as a light and what mode you’ll want to use when shooting in sunny conditions. Next up, two posts about how to improve the outcome when you shoot into the sun.

Nope. The picture to the left, from my coverage of the 2011 William Paterson University fashion show, was shot at the maximum regular ISO setting for my Canon EOS Rebel t1i – ISO 3200. When you zoom in to a 1:1 ratio, you can see some noise. However, I edited the picture in Lightroom and I also scaled it down in resolution for web viewing.

At this point, even if you click on the picture to bring up a full screen image, you won’t notice a whole bunch of noise. If you ask me, it looks great. I doubt it would look all that much different if I had put up a flash and stepped the ISO down to a more reasonable 400 or so.

Why Does the Picture Look Nice…?

Here’s another picture, from the same show and the same set up.

To give you an idea… I was sitting in the audience about 10 rows back. I had a telephoto zoom lens on the camera (70-200mm f/2.8).

The model started out in the back of the stage, where there was usable but slight amounts of light, and they walked down the runway into a bright, hot spotlight.

On the back of the stage, they were coming out ok at something like f/2.8, 1/125, ISO 3200. At the front of the stage under the spotlight, the models were perfectly well lit at f/2.8, 1/320, ISO 3200.

The key to the picture, and the reason that the noise isn’t terribly bad, is that there is enough light to brightly light the subject and allow for a proper exposure.

How Bout a Picture That’s Not So Nice…

In this picture, from the same show, there is considerably more noise. You might also notice that the picture looks a bit fuzzy as well as noisy.

The problem is that in this scene, the lights were not sufficient to light the models. The lights were dimmed for the whole scene (friendly warning, the gallery isn’t 100% safe for work), and I was shooting at f/2.8, 1/100, and ISO 3200. That was quick enough to prevent there from being too much motion blur or camera shake, but it left the pictures underexposed by about a stop.

This creates a two-fold problem. When the camera takes an underexposed picture, noise tends to be worse. Then, when you edit the picture (which I did in Lightroom, bumping the exposure by +1 and the Fill Light by 25), that noise gets exacerbated.

Add to that the fact that I cropped the picture, and you notice a lot of noise. To combat the noise, I jacked the Noise Reduction in Lightroom up to 50… and that kind of helps, but it also makes the picture a little fuzzy. It’s all a matter of compromise. The alternative would be not having a picture at all. Without a high ISO rating and without some help from Lightroom, I simply wouldn’t have been able to get any kind of usable picture from this scene with the lights dimmed.

In short, pictures taken at a high ISO can still look great if the subject is well lit. If you’re camera handles noise well and you run the image through software like Lightroom or Photoshop, a well exposed image will still look good. An underexposed image is going to look noisy, but you might just have to put up with it if you alternative is to not have a picture at all.

Here’s a quick rundown, so you can think about them next time too…

Autofocus Mode. On my Canon t1i, I can choose between One Shot Focus, AI Servo, or AI Focus (a hybrid of the two). Whenever I get ready to shoot sports, I immediately flip the autofocus mode to AI Servo. This tells the camera to continuously focus on the focus point until I take a picture, and the camera will continually refocus if the subject moves.

Why is this important? Well, in sports… people move. You also need to anticipate the action to get those good shots. So I spend a lot of time watching the game through the viewfinder with my finger halfway down on the shutter release button. This gets the camera to pre-focus on the moving subject, and when it’s action time I press the button down the rest of the way.

Autofocus Point Selection. On my Canon t1i, there are 9 focusing points. If you don’t change anything, the camera automatically selects which point it thinks it should focus on. Sometimes this works out, sometimes this doesn’t. If I’m shooting a group of people standing still, this isn’t a big deal. I can let go of the shutter release button, and let the camera choose a new focus point.

If, on the other hand, I’m in the middle of a football game… I don’t have time for second chances. When there are a lot of bodies around, I want to choose where the camera focuses. As a result, I generally manually choose a point, and it’s usually the center point. This way, the camera will focus on whatever I’m pointing the camera at.

In some sports (like wrestling), you don’t have to worry about the extra bodies and the camera will be able to do a much better job of picking out what it should focus on. As a result I’ve experimented with using the automatic point selection, because that frees me up from pointing the center of the lens directly at my subject.

This is potentially one of the biggest problems with not adjusting your settings for sports, though. If your camera is constantly guessing at the wrong focus point, try manual selection and see if that helps.

Continuous Shot. Continuous shot mode was made for sports. It’s hard to guess precisely when the best moment of action will be, and using continuous mode you can take two or three frames and hope that one of them comes out great.

Be careful how long you hold the shutter down, though. On the one hand, its a great way to fill up your memory cards too quickly. However, it can also fill up the internal memory (the buffer) on your camera and cause it to shut down for a few seconds until it finishes writing all the image data.

I found this out the hard way during a 55-meter shuttle hurdle race. In the race, a team of four sprinters take turns racing down a 55 meter stretch of track. The result is that in a matter of 20 to 25 seconds, four guys have zoomed by my camera and I’m trying to take pictures of all of them. I accidentally clipped off too many shots during the first leg of the relay, and the camera was struggling to empty the buffer and keep up for the rest of the (very brief) race.

Finally, Exposure. To me, the three settings above constitute “sports mode.” It gets my camera all set up to focus on action and take continuous shots. Once that’s done, I can worry about nailing down an acceptable exposure (or letting the camera do it in aperture-priority mode).

What’s the difference, and which should you use when?

The “One Shot” autofocus mode will focus on a specific point. When you hold the shutter release button down to pre-focus, the camera will adjust the focus until it is satisfied and then hold that focus until you take the picture. If you have the beep on, the camera will beep to tell you that it’s ready.

In the “AI Servo” mode, the camera will constantly re-focus as long as you hold down the shutter release button. If you move the camera, or the subject moves, then it will continue to refocus based on the selected focus points until you actually take the picture.

In most situations, the one shot focus is just fine. It’s perfect for portraits and still scenes, and it works fine for scenes where there is a little bit of movement but not enough to bring the subject out of focus.  One clear advantage of this mode is that you can pre-focus on a selected point, recompose the picture, and then take the picture when you’re ready.

Let’s say for example you have three people standing in a row, and the furthest person is pretty far away from the camera. You might want to focus on the person in front (and have the back two be increasingly out of focus), focus on the back (and have the front two be increasingly out of focus), or focus on the middle. With “One Shot,” you choose the focus point, focus on the person you want to, and then recompose the picture so that picture is well composed to include all three people in the frame.

“AI Servo,” on the other hand, is necessary when you’re shooting a subject that moves a lot and you want to follow that subject before you take the shot. Let’s say you’re shooting a football game. You focus on the quarterback scrambling in the backfield. You don’t just want a picture of him running; you want a picture of him getting sacked by the incoming rush. So, you press down the shutter release button, focus on the quarterback, and follow him until just the right moment. This way, the camera will continue to focus on the quarterback as he moves closer and farther from the camera until you actually take a picture.

The DNG (Digital Negative) format is an open and standardized raw image format developed by Adobe. The Canon Rebel t1i does not have the capability to directly save an image in the DNG format.

You can, in the menu, set your Canon Rebel t1i to save images in RAW format instead of JPEG. This will create a raw image file with a .CR2 extension and the closed, proprietary Canon format. You will need some sort of software to open the CR2 images, process them, and make them editable.

Personally, I use Adobe Photoshop Lightroom. It does a whole bunch of things for me. Among those features is that I can convert all of my CR2 images into the standardized DNG format as I import them. This stores them in a standardized file format that will (hopefully) be supported more thoroughly and longer. It also saves a little space, since I’ve noticed that DNG files are slightly smaller than CR2 files.

This image was taken at a cross country meet at Branch Brook Park. You can see in the background that it was a very sunny day. Alas, the starting line and various parts of the course are well covered with shade. As a result, the runners are quickly bouncing back and forth between bright sunlight and dim shade.

On the one hand, this creates problem for exposure, and this is a good time to use a semi-automatic mode (my favorite is aperture priority mode). However, the problem at hand is that the camera guessed that the image was lit with the wrong type of light. I had the camera in “Auto White Balance,” which I usually do (more on the white balance setting on your camera). I’m guessing that the preponderance of sunlight in the background tricked the camera into thinking that the entire scene was lit by sunlight, thus causing the camera to choose the wrong color temperature.

In this case, it was a relatively easy fix. After I imported the photos into Lightroom I chose a new color temperature. I went with the “Shady” preset (7500k). It was a perhaps a titch warm, but it looked much better. Then, I applied the setting to all of the shady pictures.

I could have edited a jpeg and gotten a similar outcome. However, editing jpeg files like this (adjusting exposure or white balance) degrades the image and leads to artifacting. Any time you’re editing a file, you’re better off editing the original raw file than editing a processed jpeg.

Since you never know if your camera is going to goof and pick the wrong white balance, you’d be erring on the side of caution to shoot in raw. Sure, you can “get it right” a lot of the time. But in this case, I didn’t get it right, through no fault of my own. You never know when you’ll run into a similar bit of bad luck.

Your camera most likely has a “White Balance” button or setting on it. Chances are, you probably leave it on auto most of the time. If you don’t know what it does, that may be a good thing…

The image to the left is the result of using the wrong White Balance. My student photographers were shooting a football game yesterday, and one of them accidentally changed the White Balance setting to Tungsten. The result is a blue-ish tinge to the picture.

Why? Well, let’s leave a thorough description of light and color for another day. The short version is that every light source contains different color elements, and if you leave white balance on auto your camera guesses which light source you’re using (the sun, a flash, a flourescent bulb, etc). If you don’t trust your camera (and sometimes it can go quite wrong), you can manually choose a type of light or a light temperature and tell the camera what to expect.

If you tell the camera the wrong type of light, you get something like the first image. If we told the camera the proper light source (a cloudy day, i.e. sunlight that is diffused through cloud cover), we’d get a much better image (like the one to the left).

In this case, I edited the image in Adobe Lightroom, adjusted the white balance, and got a usable picture. As an aside, this is one good reason to shoot images in RAW – sometimes the camera messes up the white balance on its own and you need to be able to fix it. If your camera processes the RAW image and creates a JPEG, you’re SOL. If you leave it in RAW and edit it later in Lightroom/Photoshop, you’ll still have an image you can use. [Note: More on this editing to come this weekend]

As a final aside, this is also a good reason to chimp your images from time to time. My students did not chimp their images (at least not very well) for the entire second half… so an entire half of the game came out blue. Thankfully, that’s the type of error we can fix in post. Some errors, you can’t.