exposure

All posts tagged exposure


Welcome back all and Happy New Year, I know it’s been a while since there’s been a blog post but I’ve been very tied up with new photo shoots. I thought we would touch on a topic that is fast becoming a “very big thing” in the photo community for both hobbyists and professionals alike. HDR Photography…it’s a term that I’m sure you’ve heard tossed around, but many people aren’t sure what it is, and what it can do for your photos.

HDR stands for High Dynamic Range. Have you ever tried to take a photo of a landscape with lots of trees and a nice bright blue sky only to discover that the photo doesn’t look like the scene in front of you at all? Perhaps the sky is perfectly exposed but the trees are all dark. Or maybe the trees look perfect but the sky is so blown out it almost looks white. What happened?

Perfect sky, dark shadows

Overexposed sky, nice shadows

You think perhaps something is wrong with your camera? Or those damn kids tinkered with your settings again? Rest assured your camera is working just as it should. The real problem is eyes. “The kids have been tinkering with my eyes?” No, you see the human eye is the best camera ever invented. It can see and properly expose a very wide range of light. Wider than any camera ever made.

Think about a night scene, you’re walking along a street, there are very bright street lights, headlights of cars, but when you look up at the sky you can still see the stars and even perhaps a blue tint to the sky. This is because the human eye can actually see a range of over 24 f-stops of light. This range of light is referred to as “dynamic range”. It is the difference between the minimum and maximum amount of light that can be seen at the same time. The very wide dynamic range of the human eye allows us to clearly discern both the bright street lights and the very dim stars all at the same time.

Unfortunately, we’re not so lucky with our cameras. Even the best digital cameras made only have a dynamic range of 10-14 f-stops. This makes our camera’s almost 1000x less sensitive than our eyes. This is why when you try to shoot the same scene with a wide dynamic range of light with your camera it doesn’t look anything like it did when you were looking at the scene through your own eyes. So what can we do to fix this? Do we have to take everyone we know with us when we travel somewhere so they can all see the same scene with their own eyes?

As awesome as that would be, although I imagine it would be tough to coordinate all of those schedules, this is where HDR photography comes in, or High Dynamic Range. HDR Photography allows you to shoot a particular scene with 3 or 5 different exposures and then using special software combine all those photos into one that has the best exposed parts of each individual photo. So now you can shoot that sky and tree scene exposing for the sky in one photo, the trees in another, and all the other pieces in between. Then combine them into one beautifully exposed photo throughout.

The last time I was at Disney’s Animal Kingdom I took these 5 photos of the “Tree of Life”. Each one is exposed slightly differently so that the set covers the full dynamic range of light present in the scene.

Tree of Life -2 exposure

Tree of Life -1 exposure

Tree of Life 0 exposure

Tree of Life +1 exposure

Tree of Life +2 exposure

When we combine all of these together using software capable of creating HDR photos such as Photoshop or Topaz Adjust, the software picks the best exposed parts of each photo to create a single one that represents the entire dynamic range of light that was in the scene. It makes a High Dynamic Range photo which looks like this:

Tree of Life HDR Photo

As you can see this photo now shows everything from the sky to the ground to the tree perfectly exposed. I’ve actually just started toying with HDR photography and it takes quite a bit of practice to get good at it. I’ll be the first to admit that I have quite a ways to go. Like with anything else though practice makes perfect! So the next time you find yourself shooting and the scene doesn’t look quite the same in your camera as it does in person, think about creating an HDR photo.

I’ve barely scratched the surface of HDR Photography in this blog post. It was really meant to be an overview of the process rather than an in-depth how to. There are many people who do this type of work better than I so it would be worth it for you to check out some of their pages and their awesome photography.

The website “Stuck in Customs” is an awesome site created by Trey Ratcliff with a great free tutorial on how to create HDR photos. Don’t forget to check out his awesome gallery as well here. After looking at these photos one thing is clear, you can’t help but be “wowed” by a good HDR photo.

As always please feel free to post your results, leave comments, and ask questions. Happy Shooting!

Scott Dengrove is a professional photographer from the NYC area. Scott’s work has been featured in many national photography competitions and published in several nationally circulated magazines and publications. In addition, his work can currently be seen in 3 exhibits at Cosi® restaurants in New York and Connecticut. For more information, and to see more of Scott’s work visit his website at www.dengrovestudios.com and connect with him on his Facebook page at www.facebook.com/dengrovestudios

 

Properly exposed background, dark subject

Do your photos sometimes look like this?

There must be something wrong with your camera right? You were trying to take a nice photo in front of a sunlit scene and for some reason the background looked great, but the people are just way too dark. What happened? They didn’t look this way in real life. Perhaps they’re unlucky. Perhaps they walk around with a preverbal “dark cloud” above their head which always puts them in a shadow.

NO that’s not it, but how cool would that be to have your own cloud follow you around? The reason the people in your photo are dark silhouettes is because your camera did not pick the right exposure for that scene. First a little background(no pun intended)…

Just before snapping a photo your camera employs many many sensors to create the finished photo, including an exposure sensor. This sensor measures all of the light in the scene and computes an average amount of light in the scene you are about the photograph. Oh there’s one more thing you should know about most exposure sensors it has a bit of a handicap, it can only see in black and white.

Aww the poor thing…I know it’s a sad story, but that’s ok because the exposure sensor has learned to deal with it’s disability and it excels at picking the proper exposure for your scene, most of the time. You see the exposure sensor is programmed so that everything it sees in the photo will look like a middle gray.

Now what’s a middle gray, well it’s a gray that isn’t too white, or too black, it’s sort of in the middle 🙂 Actually in terms of numbers middle gray for digital cameras is about 18% gray. It’s different for film. So when your camera’s exposure sensor averages all of the light coming into your scene it compares it to middle gray. Middle gray is your camera’s “happy place”. Your camera would love all photos to average out to middle gray.

In fact, that’s what it tries to do. When the average light in your scene is compared to middle gray the camera will choose an exposure that comes as close as possible to making the average light in your photo register as middle gray. This works very well in most situations. Plus several newer digital cameras have pre-defined exposure templates built-in which help your camera to nail the exposure correctly more times than not.

So then how did your people in front of the sun turn out to be dark silhouettes? Well when your camera “metered” the light in your scene it detected many bright areas, this is because you were shooting towards the sun. So imagine the photo as your exposure sensor sees it, in black and white. From the cameras point-of-view it is on average a very brightly lit scene. So the camera does what it’s programmed to do and compares this very bright scene to middle gray.

As you can see from the photo above, the few people in your scene are very dark compared to the rest of the brightly lit scene. So when the average light in the scene is compared to middle gray the camera says “the average light in this scene is much much brighter than middle gray, so I need to choose an exposure value which will darken the scene.” Hence, you get a lovely exposed sky and background, but dark silhouetted people.

A great choice if you were taking a photo of the bright background. However, you wanted the camera to set it’s exposure for those people in the scene, not the big bright background. So what can we do about it? Well your camera realizing that it’s only right about 80% has a feature that will allow you to fix this problem when taking your photo. Allow me to introduce….Exposure Compensation!

Almost all digital cameras and film cameras have an exposure compensation feature, sometimes known as “backlight compensation”. Just look for the universal symbol for exposure compensation . Exposure compensation allows you to adjust the camera’s exposure to suit your scene. In our case where our people are silhouetted we would increase the exposure by +1 or so which would properly expose for the people in the scene, but the background would tend to be a bit overexposed. This is acceptable since our main subjects are the people and not the background.

I know you guys though…you’re saying “Scott, why can’t I just move my subjects so that the sun is in front of them and not behind them, wouldn’t that work too?” Of course it would, but there are many times when exposure compensation needs to be employed, not just when the sun is behind your subject. How about taking photos of your kids in the snow? All of that white snow everywhere reflecting into your camera’s lens will cause the exposure sensor to underexpose your subjects just as if it was in bright sunlight. So we can employ exposure compensation to expose those kids properly.

Exposure compensation isn’t only for bright scenes, it works the other way as well.

What if you have a friend who enjoys boating on a lake, it can get pretty dark on there, especially towards the end of the day. Say you take a picture of him or her.

Here we have your friend against a dark blue lake background. When your cameras exposure sensor meters the light it’s going to average out as a very dark scene, much darker than middle gray. So what’s going to happen?

Your camera is going to choose an exposure that makes the whole scene brighter. This is fine if you’re goal is to shoot the lake, but you’re trying to shoot your friend, who is now very overexposed and washed out.

So what do we do to fix this? Drain the water and shoot them on sand!!! No, not quite, we can employ exposure compensation to fix our exposure but this time in the negative direction. Maybe -1. Now our friend is properly exposed. However, the lake is a bit dark now, this is acceptable though because your friend is the main subject of the scene.

So the next time you find your cameras exposure sensor is not seeing things as you see them, employ some exposure compensation and make your camera expose the scene as you want it to!

Feel free to leave comments and post some of your results.

Ok, ok, so it doesn’t exactly spell MAPS, it spells PASM big difference 🙂 But what do all those letters mean anyway?

That dial on your camera with all of those letters P, A, S and M are actually different exposure modes that you can use on your camera. These particular settings control how much of the decision for the exposure you want to use is left up to the camera. In other words, do you prefer to choose your own exposure settings, or would you like the camera to make all the decisions for you. You use the different exposure modes P, A, S, and M to tell the camera just how much of it’s brain it should use when setting proper exposure for your photo. For those who don’t know, exposure describes the light that is hitting your film or camera sensor (in digital cameras), used to create your image. Specifically, exposure describes the amount (brightness) of light hitting your film or digital sensor, and for how long that light is recorded by the film or sensor.

This is actually quite a large topic to discuss so let me tell you a bit about what’s to come. The next 4 blog posts will be related to just this topic. Today’s post is an introduction and overview of all 4 of the exposure modes, and then in subsequent posts I will explain each one in detail. Back to the content…

There are 2 terms you should know about before we continue as they are going to come up a lot in this discussion, shutter and aperture.

The shutter – is a very small opening in your camera that sits just in front of the film or digital sensor. It can open and close like a window. Most of the time the shutter is closed and does not allow any light to reach your film or digital sensor. However when the shutter release button is pressed on the camera, to take a picture, the shutter opens and allows light to strike the film or digital sensor for a pre-determined length of time which creates a photograph. This length of time is known as your shutter speed, and is usually measured in seconds or parts of a second. It can range anywhere from 1/8000 of a second to 60 seconds depending on the type of camera you use.

Aperture – refers to the size of the opening in the lens of your camera. This determines the amount of light that will be allowed  through your shutter and ultimately reach the film or digital sensor. You can almost think of aperture in terms of a water pipe. The larger the pipe, the more water that will flow through it. The larger the aperture setting used, the more light that will flow through your lens and shutter hitting your film or sensor. Aperture sizes are usually referred to as “f-stops” and range from f/1.2 to f/22 depending on the lens used on your camera.

So if those letters don’t spell MAPS, or PASM or even PAMS, what do they stand for? Programmed Auto Mode (P), Aperture Priority Mode (A), Shutter Priority Mode (S), and Manual Mode (M). Let’s take a look at what each one does.

Programmed Auto Mode (P) – This is the full automatic exposure mode of the camera. Basically in this mode the camera makes all the decisions for you when it comes to exposure. The camera will automatically set the aperture and shutter speed for you in this mode. Not only that, it will decide which aperture and shutter speed will work best for the particular photo that you are shooting. This is the mode where most beginning and intermediate photographers live. It’s very easy to let the camera decide how your photo should be exposed. But not always the best choice as the camera is merely an electronic piece of equipment and lacks the creativity and artistic eye of a human being. One way to vastly improve your photos is to take a trip out of the P mode once in a while and make some of the exposure decisions yourself. I know it can be scary, but remember #4 from the last blog post, this is digital, it doesn’t cost us anything to play around and try new things. If it doesn’t turn out quite right you can always delete it before someone else sees, the camera won’t tattle on you, promise!

Now this is where the apprehension and panic will begin to set in for some of you. In fact, there may be a few of you out there who will come to this point and say “Scott, I’m perfectly happy living in P mode and letting the camera think for me” and actually not continue to read the rest of this post. First, everyone take a deep breath, count to 3, and RELAX. There is nothing to be worried about…even if P mode is your “happy place” to shoot photos, and I’m sure for some of you it is, I do request that you at least give me a chance and read through the rest of this post. It may just make you think twice about keeping that camera in P mode for the rest of it’s life. Do cameras even have lives? Well I suppose that’s a topic for another post, anyway moving forward…

Cactus with a shallow depth-of-field, large aperture

Cactus with a shallow depth-of-field, large aperture, 75mm, f/3.5, 1/500s, ISO 200

Aperture Priority Mode (A) – In aperture priority mode you set the aperture manually and the camera automatically calculates the optimal shutter speed for your photograph. This mode allows you to take some control over your exposure while still allowing the camera to make some decisions for you. Why would you want to do this you ask? Well we know from above that aperture controls the amount of light coming through your shutter, but what you may not know is that aperture also controls your Depth of Field or (DOF). Depth of Field refers to how much of your photo is in sharp focus. Take a look at this photo of the cactus. The cactus is perfectly sharp and in focus, but if you notice the flowers in the background they have a nice soft blur on them. This draws the viewers eye directly to the cactus which is the main subject of this photo. This shallow depth of field is controlled by your aperture. The larger the aperture the “more shallow” your depth of field will be. In other words the larger the aperture setting the smaller the area that will be in sharp focus in your photo. To achieve the results shown in the cactus photo, use a larger aperture. We’ll discuss aperture and depth of field a lot more in a future post.

Stuntman captured mid-fall, fast shutter speed

Stuntman captured mid-fall, fast shutter speed

Shutter Priority Mode (S) – This mode is the opposite of the A mode discussed above. In this mode you set the shutter speed manually, and the camera determines the optimal aperture setting. As we discussed before, the shutter controls the length of time that light will be allowed to strike your film or digital sensor. However, it also controls how “frozen” the subjects are in your photograph. For example, at a baseball game when a player is just about to slide into home plate and a photographer snaps the award winning shot perfectly freezing the moment when the players hand makes contact with the plate. Or when you take a photo of a beautiful waterfall and the water looks like beautiful creamy flows. The sense of movement in these photos are all controlled by the shutter speed. The faster the shutter speed, the more “frozen” and sharper, the action will be in your photo. Take a look at this photo of a stuntman captured in mid-fall. To freeze his motion a very fast shutter speed was used for this photo. We will discuss shutter speed more in depth in a future post.

Manual Mode (M) – For those who want the ultimate control over their exposure, this mode is for you! In this mode the camera does no thinking at all. Both aperture and shutter speed are set manually by the photographer, hence why the call it Manual Mode. This mode can seem a little daunting to use at first, but after you play around with it for a while you’ll get a very intuitive sense of which aperture and shutter speed to use for a particular situation. As they say necessity is the mother of invention, and when you don’t have the camera helping you out with exposure settings you pick up real fast what works and what doesn’t.

We’ve barely scratched the surface of exposure modes in this post, but I implore you to take a trip out of the P zone every once in a while. Please comment with your experiences and share some photos with us. Next time we’ll begin to look at the 4 exposure modes more in depth. Until then, go out and shoot some great photos, it’s the only way you’ll become a better photographer.