Increasing ISO to Reduce Grain in Your Images (Podcast 661)

Increasing ISO to Reduce Grain in Your Images (Podcast 661)

Today I’m going to provide some clear evidence of the benefits to increasing your ISO to help reduce grain. Sounds crazy, I know, but this works, and after this post I think you’ll believe me.

I have been meaning to do this for a while, as although I’ve talked about Exposing to the Right and how increasing the ISO can help to reduce noise, I do realize that this is counterintuitive. I also received an email from listener Matthew Wells, as follows:

In several podcasts, you mention how you will shoot higher ISO levels by exposing to the right to brighten the image to reduce the visible noise. Could you put together a short video for your Youtube channel to show your methods for doing this? I have tried to play with the idea a little without success so far.

Matthew Wells via email.

Thanks very much for your suggestion Matthew. I decided to do this as a straight post rather than a video so that I can provide some examples that you can open and look at directly, and I think this format will help more for now.

Why Take Control?

So, the first thing I want to do is explain why I take control, with an example you can try for yourself really easily. All you need is something white, and something black, or a very dark color. Literally, a large piece of paper or a bedsheet is fine for the white thing, and a dark coat will work for the dark thing, and this works best if the things you find are not too glossy or shiny.

In my studio, I have both white and black backgrounds on a pulley system so that I can change the background for my photographs quickly. I have a roll of black paper that we won’t use for this, and a roll of white paper, and a roll of felt cloth, that we will use. You can see what I mean in this photograph, with the black background extended part way so that you can see them both.

Black and White Backgrounds

White is Grey!

Here now, is a photograph of the back of my camera, in LiveView, and set in Aperture Priority mode with Auto-ISO turned on and no Exposure Compensation dialed in. There are a couple of things that I want you to look at. Firstly, while noting that I’m pointing the camera at a sheet of white paper, look where the data of the histogram is falling. All three channels are only one third from the left side. This means as you can see from the photo that the white background would be recorded as grey, not white.

White is Grey!

The other thing that I want you to look at is that the shutter speed has been set to 1/160 of a second and the ISO is 4000. I set the aperture to f/5.6 myself, and the camera has automatically selected the other settings.

Black is Grey Too!

Now let’s look at another photo, and the only difference between the two images is that I’ve drawn down the black felt background, as you can see in front of the camera. I didn’t touch the camera other than to half-press the shutter to display the exposure details. Look at what’s happened to the color of the background in LiveView. Nothing! The black background is also grey, and the histogram shows us that it’s very similar, if not almost identical to the grey in the photograph of the white background.

Black is Grey Too!

We can also see that the settings have changed. The shutter speed has been increased to 1/15 of a second from 1/160 and the ISO has gone from 4000 to 12800. Using the Exposure Calculator in my Photographer’s Friend app I can quickly see that the camera has changed the exposure from 17 2/3 EV to 16 EV, a difference of one and two-thirds of a stop. Just to quickly walk through this, the shutter speed change is 3 and a third of a stop, and the ISO change is one and two-thirds of a stop, so if we deduct the ISO change from the shutter speed change, we get one and two-thirds.

I could have left Auto-ISO off to make that easier to understand, but I also wanted to show how the camera would want to increase the ISO instead of taking the shutter speed much longer.

So, what does this tell us? Well, for one thing, it tells us that our cameras are still pretty stupid when it comes to metering certain scenes and setting its exposure. This is why I almost always shoot in Manual mode. You can use Exposure Compensation too, and which method you use is completely up to you, but I find using Manual easier, mostly because I’ve been doing it so long, but also because as the size and position of the various elements in your frame change, the exposure will also change, so you have to continuously adjust the Exposure Compensation, especially when you are Exposing to the Right, which we’ll discuss shortly.

This is extremely important when photographing things like the Red-Crowned Cranes that we shoot on my Japan Winter Wildlife Tours. These are a white bird against a white background when they are on the snow, but when they fly, the background is much darker, and as you’ve seen, the camera always tries to make a dark scene brighter and a bright scene darker.

So if you dial in up to plus two stops of Exposure Compensation, which is required to make the snow and white bird actually white, then recompose and start to include a darker background, the camera will increase its exposure to lighten the dark background, and the white bird essentially becomes completely over-exposed.

A Real-World Example

Here is a screenshot of Capture One Pro showing two photographs that I shot as I explained this to a participant on this year’s tour. To prove the point, I put the camera into Aperture Priority mode and pointed my camera down so that only white snow was in the frame. This is how I set my exposure in Manual Mode, because the cranes are also mostly white.

Exposure Example
Exposure Example

Keep in mind that to set my exposure in Manual Mode, all I do is increase my exposure while looking at the caret on the meter, until it’s between +f and+2 stops over zero. For brightly lit snow, it’s closer to +1 and for snow on an overcast day, it’s usually around +2 stops. Now that I’m shooting with the mirrorless EOS R camera, I have a live histogram and can actually just keep on increasing the exposure until the data on the histogram is almost touching the right shoulder, but without this feature, I used to just take a test photo, just like the one you see on the left here. As long as it’s white, but not over-exposed, I know that I’m then good to go, and because the bird is white, like the snow, and under the same light, I am then free to just shoot away until the light changes again.

In an automatic exposure mode though, such as Aperture Priority in our example, as you can see, as soon as I recompose to include an even slightly darker background, the camera tries to lighten up the scene, and my whites start to get over-exposed. So, if you want your whites to be white, not grey, you really must take control of the exposure by locking it down in Manual mode, or you have to change your Exposure Compensation every time you recompose.

I’ve added a few bits of markup to the screenshot to point out a few key things. First, notice on the left that I have +2 stops of Exposure Compensation dialed in, and I’m in Aperture Priority mode for this example. Also, note how the shutter speed changes from 1/500 of a second for the correctly exposed shot and drops to 1/200 of a second as the camera tries to compensate for the darker background. It would probably make more sense to use shutter priority for birds in flight, but as an example, it doesn’t really matter. The point is, the exposure runs off as we recompose.

Also note that the red that you see over the bird and the snow are not markup, that is the Exposure Warning in Capture One Pro. You can see that this is turned on also by the fact that the icon in the toolbar is yellow. This is grey when the Exposure Warnings are turned off.

Higher ISOs are Less Grainy with ETTR

So, let’s move on to the benefits of increasing the ISO rather than being afraid to, for fear of introducing grain. Most people have the idea that increasing the ISO causes grain in your images, and of course, that is true, if you leave the exposure up to the camera, because the camera is generally going to underexpose your images. Here is an example with two photos that I shot as a test, just of some ornaments and a little metal EOS R that I got as part of the release campaign here in Japan.

ISO Example
ISO Example

If you click on the image to open it up in the lightbox, even at the web size you’ll be able to see the visible grain in the right image, which I shot with the camera’s built-in meter at zero, exactly where the camera thought the exposure needed to be. It was indoors late afternoon, and because the ISO performance is so good on the EOS R, I had to increase it to 51200 for you to really see the grain.

For the left image though, to prove my point, I used Aperture Priority mode again, with +2 stops of Exposure Compensation dialed in, as I’ve circled in red on the left of the screenshot. You can see underlined in red, that both images were shot at 51200 ISO and the +2 stops images shutter speed was 1/125 of a second, exactly two stops slower than the right image, which was shot at 1/500 of a second.

Comparison

Here now, is a 100% crop of each of the images from the above screenshot, so that you can check the details. As you can see, despite them both being shot at ISO 51200, the grain visible in the +2 stops version, which is I should emphasize, exposed to the right, is virtually undetectable, compared to the image at the camera’s recommended metering, which is very grainy.

Again, if you click on the images to view them in the Lightbox you’ll get the best view of the detail, but the difference I’m sure you’ll agree is huge. Note too that although in comparison, the lighter image may appear too bright, it’s actually only slightly over-exposed, with the highlights just clipping slightly. If you wanted to darken it back down again, you could use the Highlights sliders or a tone curve, and you’d still get a cleaner image by exposing to the right like this, then darkening it back down to suit your needs.

Another Take On This

Another take on this, which is perhaps easier to understand from a shooting workflow perspective, is the fear element that generally prevents people from increasing the ISO. Imagine you are in a situation where the light is low, and you are already forced to shoot your image at 12800 ISO, at 1/125 of a second to avoid subject blur, and you need an aperture of f/8 for sufficient depth of field. The camera is metering at zero, with the information in the histogram way over on the center decreasing down the left side. The actual ISO will depend on your camera, but many people start to shy away from shooting higher than around 3200, some even as low as 1600. For me, as I get used to the EOS R’s ISO performance, I would probably not have gone higher than 12800 in the field, because I hadn’t yet done these tests. On my 5Ds R bodies, I tried to avoid going above 6400 ISO, based on tests.

ISO 12800 Camera Zero Metering @ 100%
ISO 12800 Camera Zero Metering @ 100%

As you can see from this image, with its histogram embedded for reference, there is a little bit of grain starting to creep in. Still incredible for a 12800 ISO image at zero metering, but you can see the grain.

+1 Stop Increase

So, what do you? Most people would shoot at 12800 or whatever your own personal soft-ceiling is, and be afraid to increase the ISO any more for fear of introducing any more grain, but wait! To get your histogram data over to the right, in this hypothetical example, our only option is to increase the ISO further. Here is another image in which I’ve increased the ISO by one stop to 25600.

ISO 25600 +1 Stop @ 100%
ISO 25600 +1 Stop @ 100%

This image is double the ISO at 25600, but the grain is actually less than the 12800 ISO image because the ISO increase has made the image brighter. You can see from the histogram, which I screen-captured from the full sized image, not the cropped version, that although it’s more to the right than the previous images, there is still a gap.

One More Stop!

For this next image, I increased the ISO yet another stop, to 51200. This is actually the lighter image of the pair that we just looked at in my first example. and as you can see from the histogram, we are now exposing to the right. There is a small gap, but that’s Capture One Pro giving us a little back. In the camera, the specular highlights were just starting to over-expose, so this is as far as I would like to take this image exposure-wise.

ISO 51200 +2 Stops @ 100%
ISO 51200 +2 Stops @ 100%

A Few Tweaks

You can see that increasing the exposure with the ISO has actually reduced the amount of grain visible in the photograph. The darker parts of the image are now starting to suffer from a little bit more grain, but if you really had to push your ISO this far, you could do a few tweaks such as adjusting the levels and curves to darken down the dark areas a little, which helps to mask the grain that does creep in there.

ISO 51200 +2 Stops Tweaked @ 100%
ISO 51200 +2 Stops Tweaked @ 100%

And I haven’t even touched the noise removal options. They have been set at the default settings all along. So, as you can see, although I know it’s counter-intuitive and probably goes against everything you’ve been taught, if increasing the ISO helps you to expose to the right, then the brighter image will almost always have less grain in it than the lower ISO image, if the lower ISO image is already very high.

I should add at this point, that for lower ISOs, where you really can’t see any grain anyway, there is something called ISO invariance, that we looked at in Episode 520, which basically means that you can shoot according to your camera’s meter at lower ISO, and then increase the brightness in post if necessary, and you still won’t see any grain, because there is nothing in the base image for you to amplify. What I’m talking about today is more for higher ISOs, which is generally the area that starts to get people nervous. It’s that fear that I’m hoping I can help you to break through with this post.

My ETTR Workflow

I’m sure that part of Matthew’s original question was also referring to how I actually adjust my exposure, so I’d like to add a little more detail on this before we close. As I mentioned earlier, I pretty much always shoot in Manual Mode, though occasionally I do shoot in Aperture Priority and turn on Auto-ISO, and use Exposure Compensation to Expose to the Right. My thought process is similar in either shooting mode.

Aperture

I start usually by selecting my Aperture, as this directly affects my depth of field, and that is often one of my most important decisions as I start to set my exposure. Once I have set my aperture to something appropriate, i.e. a small number like f/2.8 for a wide aperture and shallow depth of field, or a larger number like f/11 for a smaller aperture, and more depth of field.

Shutter Speed

I generally then set my shutter speed in Manual Mode. I will select a faster shutter speed, like 1/500 to freeze a moving subject or a faster shutter speed of 1/1600 of for fast moving subject or birds in flight. Or I might select a slower shutter for a landscape, or even use a Neutral Density filter to slow down the shutter speed even more for some of my landscape work. If I am in Aperture Priority mode I often control the shutter speed by setting a minimum speed in the camera settings, just to help the camera to avoid going too slow, but getting faster is generally not a problem in these cases.

ISO

Finally, I adjust my ISO. It’s actually my ISO most of the time that I use to actually adjust and fine tune my exposure. This is why I am really enjoying the new Control Ring on the front of the Canon RF Lenses, because I have this set to adjust my ISO, so I can now really easily adjust it while looking through the viewfinder and keeping my eye on the live histogram.

With the live histogram I literally just adjust my ISO until I see the data on the histogram just about start touching the right side. For landscapes, even with my older DSLR bodies, I used to turn on LiveView and do this on the LCD.

Highlight Warnings

It’s also important to turn on Highlight Warnings on your camera so that you can see when you do start to get over-exposed and pull it back a little. I will often use a very small amount of flashing or the “blinkies” as an indication that I’m right where I need to be exposure-wise, but once a larger area starts to blink, I pull the exposure back a little.

RGB Histogram

And it’s also important to use the RGB histogram rather than the black and white brightness histogram, because the brightness histogram is an average of all three channels, and doesn’t always show you if one color is becoming overexposed before the others, and it can cause a nasty blotchiness in your colors if you allow one color to blow-out.

Camera Meter in Manual Mode

Also, note that even when I am in Manual Mode, I still reference the camera’s meter reading. People often think you are flying blind in Manual Mode but that is not the case. When you half-press the shutter, the meter still kicks in and shows you where it thinks the light levels are on the meter, so for example when I am adjusting for the white snow, I can see the caret moving on the meter scale, and use that to see when my settings result in my exposure being two stops over.

If it’s not a white snow scene, I will just guess at where the caret should be on the meter scale, based on the balance of light and dark objects in the scene. If it’s literally 50/50, then the meter might be at zero, or perhaps just a little over to get my histogram data over to the right.

Note too that I’m always talking about the right-most data, not all of the histogram data. The rest of the data represents your mid-tones and shadows, and can, depending on your scene, extend all the way over to the left shoulder. Occasionally you might shoot a scene with very high contrast, and find that even when exposing your highlights to the right, your shadows can start to spike up the left side. That’s when you might consider merging multiple images in an HDR photo, but personally, I have not had to do that for many years, while using my ETTR techniques.

Thanks for the question Matthew, and I hope this was useful for all that stop by and take the time to read or listen to this episode.

Complete Namibia Tour & Workshop

Before we do finish, I’d like to mention that we’re at the time when we need to start finalizing the numbers for my 2020 Complete Namibia Tour & Workshop This is an epic trip that encompassed landscape, culture and wildlife and we next year will be my sixth visit, and the tour just keeps getting better and better, so I’d love for you to join me there. Please check out the details at https://mbp.ac/namibia2020 and drop me a line if you have any questions. If you visit this post after the 2020 tour closes for bookings, check our Tour & Workshops page for a list of currently available tours.

Complete Namibia Tour & Workshop 2020

Show Notes

Check out my ISO Invariance article here: https://mbp.ac/520

See details of my 2020 Complete Namibia Tour & Workshop here: https://mbp.ac/namibia2020

Music by Martin Bailey


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Podcast 216 : Photography Fundamentals for the Beginner – Part 1

Podcast 216 : Photography Fundamentals for the Beginner – Part 1

Last week, a new user on the forums, Chua Kim You, user name redpandafire from Montreal, Canada, revived an old thread from June 2004. I’d posted and article called “Fundamental Advice for Photographer’s Getting Started”. I had to admit, that looking back at this post from over five years ago, there were a lot of things that I would have written differently.

The article itself is a little presumptuous and I would have worded much of it differently now than I did back then, but I as a photographer have also changed a lot over the last five years, and so I decided to sit down and think about how I would write this today, and that is the topic of today’s post and podcast. In fact, this is just part 1. I’m going to release part 2 next week, so stay tuned.

I’m going start afresh today, and just go through what I would probably tell a beginner today. I should say that this is not an article on how to start out as a professional photographer and set up a business etc. It’s more targeted for the total beginner that has just bought a camera, or maybe just made the jump from a compact digital to a digital SLR camera, and wants a kick-start to get them up to speed on the fundamentals. I should also say that it is of course not comprehensive. To cover everything you need to know about photography would require multiple very fat books, not a single Podcast episode. This should be a good primer though, so here with go with my…

Photography Fundamentals for the Beginner (2009)
So, you’ve stumbled across photography, and started to make pictures with either a high-end compact digital or a digital single lens reflex camera, or DSLR. Photography is great fun, and to really put yourself in a position to get started quickly, and learn the craft well, I suggest you take the following points into consideration as you experiment with your new camera.

Left Brain/Right Brain
Firstly, realize that although some people can come at photography from one side or the other, in general, to be a good photographer you’ll need to work at being both an artist and a technician, quite often at the same time. People will tell you that it’s not about the gear, and that’s true to an extent, but don’t interpret this to mean that you don’t need to learn how to use your gear or learn some fundamental technical rules and theories. Some of the technical stuff won’t make sense at first, and that’s OK, but the sooner you plant the seeds, the easier it will be to all fall into place later.

Read the Manual
Some people joke about never reading their manual. Some people boast about this, thinking that they are so cool or intelligent that they don’t need to. Both of these activities won’t help you to learn how to use your camera to its fullest potential. No matter how many times I upgrade my camera bodies, the first thing I do is to sit for an evening and read the manual, with my new camera at my side. When upgrading, there are some paragraphs and chapters that are pretty much a straight copy and paste from the previous manual. In this case, skip over it quickly, but don’t ignore it. As this is a guide for beginners though, I assume this is your first camera, so do read the entire manual for your camera, and for any lenses that you have also bought, if you have a DSLR. When you are done reading the manual, you’ll have a good knowledge of what the various settings are for, and how to change them.

Have Fun!
If you are already getting out, experimenting and having fun, that’s great! If not, by all means continue to read/listen to the rest of this, but take your time and don’t get bogged down in details. There is a huge amount of information out there now. Just looking through our Photography Podcasts will certainly help, but the Internet is literally teeming with information on photography these days. So much so, it really is easy to concentrate so much on studying about it all, and trying to learn every detail that you forget to just get out and shoot. Ideally you’ll be able to strike a balance, where you study some of the time, then get out and shoot and experiment to your heart’s content as well.

Exposure Basics
There are three elements that will influence your camera’s exposure, and these are the aperture, the shutter speed and the ISO. In the film days ISO was set by the film you bought, and so once you had a roll of film in the camera you were pretty much stuck at that ISO, but now with digital cameras you can change it freely, and so it really can be counted as a per/frame exposure setting.

Night JettyAperture – This is the hole inside the lens that controls how much light gets through during the exposure. Apertures are somewhat confusingly rated by small numbers for wide apertures, and large numbers for small apertures. So F2.8 is pretty wide, whereas F32 is pretty small. The aperture size is represented by an f-number and often referred to as an f-stop. Common f-numbers or full f-stops are F1.4, F2, F2.8, F4, F5.6, F8, F11, F16, F22 and F32. With each of the f-number increments, the amount of light that enters the camera to make the image is reduced by half. The weird numbering for f-numbers comes from the fact that they are a ratio of the focal length and the aperture. For example, if you have a 100mm lens with a widest aperture of F2.8, the widest aperture is about 36mm. If we divide 100 by 4, the next full f-stop down, we get a 25mm aperture, which is half the area. Let’s not get too hung up on these calculations for now though. Just note that the larger the number, the smaller the aperture and the less light that gets into the camera.

Shutter Speed – This tells the camera how long you want it to allow light into the camera. The longer the shutter speed, the more light enters the camera and the brighter your resulting photograph will become. Also, as the world around us is moving, the length of your shutter speed can drastically change how your image looks. If you photograph a lake with a fast shutter speed of say 1/250th of a second, you will freeze any movement in the water, and be able to see all of the waves on the surface of the lake pretty much as you do just watching it with the naked eye. If however, you do a very long exposure, like in my example image, number 2320 (above right), all of the movement blurs into a smooth flat surface that we can’t actually see with the naked eye. Shutter speeds are also counted in stops, by halving or doubling the amount of time. One stop faster than 1/250 of a second is 1/500 of a second, and one stop slower is 1/125 of a second and so on.

ISO – The ISO rating is the sensitivity of the film or digital sensor to light. Standard ISO are 100 or 200. It used to be that 100 to 400 ISO was the safe range, before you started to get too much noise or grain in your images, but cameras these days are happily shooting very clean images at much higher ISO, so experiment with your camera to see what you can shoot at, and use the entire range as necessary. As with aperture and shutter speed, ISO is also counted in stops, and doubles and halves as you increase or decrease the ISO.

Note too that most cameras these days allow you to select apertures, shutter speeds and ISO ratings in one third increments, so as you change these values you will have two other numbers in between the full values that we looked at here.

Any of the above values will change the exposure. You can also raise one and lower the others to achieve the same exposure. For example, say we start off with the camera set to ISO 100, with an aperture of F5.6 and the shutter speed set to 1/125 of a second. If you change your aperture from F5.6 to F8, you will reduce the amount of light getting in to your camera and therefore reduce the exposure by one stop. To make up for that with the other settings, you could increase the ISO from 100 to 200, or you could increase the shutter speed from 1/125 of a second to 1/60.

Likewise, if you want to have a faster shutter speed to freeze some action, you could increase it by say two stops from 1/125 to 1/500 of a second, and change the ISO and aperture accordingly. You could change both by one stop, moving the ISO to 200 and the aperture to F4, or you could change just the aperture down to F2.8, assuming that your lens goes that wide. This is a little bit complicated, but hopefully will be making some sense. Don’t worry if it isn’t. We may be just sowing seeds here and it will all fall into place at some point, I assure you.

Depth-of-Field
Depth-of-field is the area of the image that is in focus. Let’s look at example image #2289 (below), where we can see the second statue from the right is in sharp focus, but the one to the right in the foreground and the other statues in the background are all blurred. This is because the second statue from the right is inside the depth-of-field, and the others aren’t. This image was shot with a wide aperture of F2.8 and a long focal length of 175mm, using my 70-200mm F2.8 zoom lens.

Huh?

Huh?

The depth-of-field is directly affected by the aperture, the distance to subject and the focal length of the lens. We discussed the way a smaller aperture lets in less light above, but also, as we make the aperture smaller, we increase the depth-of-field. If we move further away from the object or focus on something deep in the scene, we also increase the depth-of-field, even without changing the aperture.

The closer the subject gets, the shallower the depth-of-field, and this is why close-up, or macro photography requires smaller apertures to achieve enough depth-of-field to get even very small subjects, like the mushroom in image number 2395 in focus (below). In fact, even with an aperture of F11, with a 100mm macro lens, the mushroom which was probably around 1cm in depth is not all in focus. The front and back edges of the head of the mushroom is slightly out of the depth-of-field.

Mushroom and Moss

Mushroom and Moss

Also, to illustrate how wide angle lenses have deeper depth-of-field, let’s look at image number 2283 (below) which was shot with an ultra wide angle lens, at 14mm. Here I used F8, a wider aperture than the mushroom shot at F11, and yet everything from the tree that we are looking up into in the close foreground, to the distant trees along the bottom of the frame, is in focus.

Inside the Lacy Leaf Maple

Inside the Lacy Leaf Maple

I personally like to shoot with wide apertures and create lots of creamy bokeh, which is the out of focus areas of an image, whenever possible. As a general rule though, when I shoot landscapes, as with most people, I try to get the entire scene in sharp focus, so I work to get a small aperture. It’s a fine balance though, because if you go too small, past F16 for example, the image starts to become less sharp, even though the depth-of-field increases, so you don’t want to just shoot everything at F32.

If I’m doing flower shots, or portrait work, I generally try to get as little of the image in focus as possible. It takes experience to know how much depth-of-field field any focal length, aperture and focus distance combination will give you, but luckily there are tools to play with too. If you have an iPhone, search for one of the great Depth-of-Field tools like DoF Calc. There is also a great tool that works on Windows called Barnack, that you can play with to see how the focal length, distance to subject and aperture create varying depth-of-field.

Get Out of Program Mode
To control the aperture and depth-of-field, as you become more comfortable using your camera, try to move out of the P or Program mode. The Program mode allows for very little control over the Aperture and Shutter Speed. If you don’t understand how to change the camera’s shooting mode, again, look in your manual.

Most of the time, you’ll want to shoot in either Aperture Priority or Shutter Priority modes. Aperture Priority mode allows you to set the camera’s aperture, and the camera will then set the shutter speed accordingly, by looking at the scene and evaluating with the camera’s meter how much light you need to make an optimal exposure. If the scene is very dark, you’ll have a long shutter speed, if it’s very light you’ll have a short shutter speed. You’ll use aperture priority when you want to control the Depth-of-Field (see above).

If you need to tell the camera how fast you want the shutter speed, and don’t care about the depth-of-field, then you could try Shutter Priority instead. You might use this for example when you are shooting sports or racing cars, when you need to stay above a certain shutter speed to ensure that you freeze the action. Many people find though that selecting the aperture in Aperture Priority, and selecting a high enough ISO to maintain a fast shutter speed give the most control. There is also Manual Mode, in which you pretty much take full control, but that’s a little bit more advanced and probably outside of the scope of this post.

Exposure Compensation
The light meters and computers in our cameras today are incredibly intelligent. They have scenes in their memory that they compare what you have framed, and try to adjust the exposure they select accordingly. But at the end of the day, they are still machines and they make mistakes. To over-ride this, your camera has a feature called Exposure Compensation. This is usually adjusted by the big dial on the back of your camera; but again, refer to your manual to make sure you know where this is.

You will need to use exposure compensation when the scene you are photographing is extremely light, or extremely dark. For example, to shoot an image like number 2183, which is basically a pale grey tree in a field of snow with a white sky (below), I would have to use around plus one or plus one and a third of a stop exposure compensation. This is because the camera tries to make everything look like an 18% or mid-tone grey. To compensate for this and make the snow look white, I increase the exposure.

Lone Tree on a Hill

Lone Tree on a Hill

If the scene was very dark, like say a brown bear in a dark cave, I would, from a great distance, probably have to decrease the exposure by around one stop, so that the camera didn’t make the scene too bright, which would ruin the mood of the shot. Unfortunately I don’t yet have an example image to show you here.

Check the Histogram
The last thing to note on exposure before we move on is that these days with the digital revolution, we’ve now got the almighty histogram to rely on. So, reading histograms is a little bit complicated and I don’t want to get into too much detail here, but basically a histogram is a graph that you can display on the back of your camera, and I do suggest that you set your camera so that this is viewed when the image that you just shot is displayed in preview mode on the LCD.

Basically the histogram’s graph maps the darkest tones in your image to the left and the lightest tones of your image to the right. The more tones you have on the dark side the higher the graph gets on the left, and the more tones you have on the highlight side, the higher the right side gets and the closer to the right side it gets. Basically what you want to look out for is that the right side of the histogram doesn’t touch the right side or the right shoulder of the histogram, unless you know why it’s there. Say you have the sun in the shot, and you are going to let that overexpose slightly, so you don’t have to make the rest of the shot too dark. Otherwise you basically want to stop the histogram from hitting the right shoulder.

You also want to turn on the flashing highlight warning if your camera supports that, and again, check the manual to see if this is supported and how to turn it on. You’ll have the histogram and the image both displayed on the LCD, and if there are areas that are blown out, they will be flashing. If you don’t care about these areas that we call specular highlights, then don’t worry about it, but if you think that the area that is flashing should be within the dynamic range of the image and not over-exposed, then you’ll want to use the exposure compensation to reduce the exposure slightly until the flashing highlights stop flashing and until the right side of the histogram stops hitting the right shoulder.

See more information on shooting for highlights in my Dynamic Range post.

Use RAW
One last thing that I want to mention before we finish for this first part, is that I suggest you get used to shooting in RAW mode very early. If you want, do your practicing and experimenting in JPEG mode, but RAW is actually more forgiving if you get the exposure off a little, and the image quality is better, because the camera doesn’t compress the image, losing some of the detail, especially in heavily textured areas. Using RAW does bring a little overhead in post processing, but tools like Lightroom for Windows and the Mac and Aperture for the Mac only make it so easy to work with RAW files, there really is no excuse, especially as hard disk space is also now so cheap. Do yourself a favour, and just get used to shooting in RAW.

Next week we’ll get into some fundamental composition techniques, and a few other areas, so please do stay tuned if you are finding this useful.

Thanks to Chua for reviving that old thread and prompting today’s and next week’s Podcast. It’s been fun to do this, and hopefully many others will find it useful too.


Podcast show-notes:

Depth-of-Field Explained in detail: https://martinbaileyphotography.com/2009/09/09/podcast-132-depth-of-field-explained/

DoF Calc: http://www.apptism.com/apps/dof-calculator

Barnack: http://www.stegmann.dk/mikkel/barnack/

Music from Music Alley: http://www.musicalley.com/


Audio

Download the Enhanced Podcast M4A files directly.