The exposure triangle is made up of three components that work together: aperture, shutter speed and ISO. The first thing, aperture, is marked by the f stop (e.g F5, F4.5) on the camera, and is how large iris of the camera is. In layman’s terms, this means how large the hole in front of the lens is. When the f stop is raised, the hole gets smaller, and the image gets a larger depth of field. A larger depth of field allows for more of the image to be in focus. The negative side of this is that less light is let in, due to the fact that the aperture hole is smaller.
Shutter speed controls how long the camera’s shutter is open. The longer the shutter is open, the more light is let in, as the lens is exposed to more light. Thus, if quick movements are to be captured in an image, the shutter speed needs to be lowered. If the shutter would be open for too long, there will be motion blur, blur caused by the movement of an object before the shutter is closed. In some types of photography, these are desirable aesthetic effects; however, in most types of photography this is not desired and should be avoided.
The last component of the triangle is ISO, the light sensitivity of the camera. The higher the ISO is, the brighter the image will be, as the camera is able to take in more light from what exists in the image. Thus, ISO is very useful when you need to make an image brighter while keeping a fast shutter speed and/or high aperture. The disadvantage of this is that a high ISO creates more “noise” or film grain, which basically means that there are small particles in the image, similar to the effect of a static TV.
Together, these three components make up the exposure of the image. When used correctly, this makes for a nice, well-exposed image with adequate lighting. To have that, you want to use all three components correctly, which is how they are related. For an example, if you want to shoot an image of a field outside, and you want all the flowers in focus, you’ll need to have a very high aperture. That will make the image very focused, but very little light will be let in. Thus, you need to adjust the two other components so that it will be brighter. You’ll first of all want to have a longer shutter speed, so that more light will be let in to the lens. To avoid heavy film grain and overexposure, you will want to keep the ISO fairly low, since the long shutter speed already lets in enough light. Overexposure is when the image is too bright for the features to be seen, with entire sections possibly even completely white. When taking photos, you want to avoid this at all costs.
As a photographer, you need to understand how to use manual mode in order to make your images the best they can be. A DSLR is a very powerful tool, and with the help of manual mode you can be in control. With manual mode, you can adjust virtually every aspect of a photograph, and control what your camera does. Rather than letting the camera choose what it does, you can do whatever you want in the image.
Below are my favourite photos from this unit.
Freezing action: This image was taken in-class, with the help of my classmates Jonathan and Daniel (it may even be featured on their blogs too). Although we used Jonathan’s camera, we all were involved in the process of getting this perfect shot. We took multiple photos, discussing how we could make it better. What works in this photograph is first of all that the shutter speed is just right. Thanks to being very fast, we were able to capture the exact moment the balloon burst. In order to balance this exposure-wise, we used a higher ISO. What also works is that the composition is quite good, with the water being perfectly in frame, not “kissing the frame”, and the arms providing visual weight to balance it out.
Motion blur: I think this image is one of the best I’ve taken in this unit. To get the blurred effect, I lowered the shutter speed. Since the train was going much faster than this, I knew there’d be motion blur. I still kept the ISO at a low level, since the shutter speed was slow and the area well-lit. I zoomed in a bit, so that the train was completely centered, which I think was a good framing decision since it just emphasizes the train and keeps everything else out of frame.
Panning: Here, I used a slow shutter speed of 1/60 to get the blurry effect in the background. However, since it was nighttime, I also needed to raise the ISO, so that the image wouldn’t be underexposed, so the ISO was at 800. Then, I focused my camera manually at the taxi, and followed it with the camera for a sequence of images, and later selected the best of them where the taxi is clearly in focus while the background is blurred.
Shallow Depth of Field: This image was shot with a low aperture, to get a shallow depth of field meaning that not all of the image is in focus. Rather than using motion and slow shutter speed to get a blurred background, I used manual focus to only focus on the pine cone. It was a sunny afternoon, so the ISO stayed low. I also didn’t want to keep it too high since I found that the shadows on the pine cone helped increase the three dimensional feel of form.