By Peter Emmett © 2012
In part 1 of this series we started looking at the basic controls of the camera in order to start your relationship with your camera. This part we look at how the shutter button can make a huge difference in your images and the different type of auto focus system that cameras employ.
Using the Shutter Button - What They Didn’t Tell You
The shutter button is the single most important part of a camera. Now that may sound like a weird statement, but without a mechanism for triggering the camera to take the shot, no photo would be possible. If that’s all it does, then why spend time on it here right at the beginning of the series?
The shutter button not only helps you take the photo, but by learning how to use the shutter button properly, it also provides you with a way to immediately start taking better photos. It may sound a little strange talking about the shutter button like this, but after you learn to simply press the shutter button half way before taking the photo, it’s amazing how much more you can do with you camera.
So what does pressing the shutter button half way do exactly? If you’ve ever been frustrated by your camera always missing the shot of your child diving into a pool or running past the finish line in a race then you’ll have experienced something called shutter lag. Shutter lag is the time delay between pressing the shutter button and the camera recording the shot. The amount of shutter lag you experience will depend on the camera you have. However you can improve or minimize the shutter lag without spending thousands of dollars on the newest camera. How? By learning to press the shutter button half way before taking the shot.
Simply put pressing the shutter button half way before taking a photo, forces the camera to prepare itself for taking the photo and severely decreases shutter lag. When you press the button to take a picture, the camera has to calculate a lot of different things (especially if you’re in Auto mode). Depending on how powerful the camera’s internal computing power is will affect how long the camera takes to make all the necessary adjustments and calculations which causes the delay between pressing the shutter button and taking the photo. This delay is often the reason people think that they need a DSLR or more powerful camera.
By pressing the shutter button half way the camera prepares itself to take a photo by making all the necessary adjustments and calculations so that when you fully press the shutter button all the camera has to do is record the photo without having to think about anything else, which can almost eliminate shutter lag.
To illustrate my point I took these photos of cars driving past my office building at roughly the same speed. They reveal the difference between taking a shot without preparing the camera and preparing the camera by pressing the shutter button half way before taking the shot.
The shots were taken when the car reached the middle of the picture, illustrated by the red square. When fully pressing the shutter button to take the shot, the cars have nearly exited the right side of the photo.
Typical photos for a camera when fully pressing the shutter button
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| Sony DSC-W170 |
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| Canon G12 |
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| Canon 5D MKII |
However when preparing the camera to take a shot by pressing the shutter button half way and then fully pressing it to take the shot, the cars are still in the middle of the photo.
Instant improvements simply by pressing the button half way to prepare the camera
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| Sony DSC-W170 |
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| Canon G12 |
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| Canon 5D MKII |
Pressing the shutter button half way takes a little practice, but once you’ve mastered it, it will become second nature for you. Two common reasons for using this technique are (1) to focus on a subject and then recompose the photo and (2) to pre-focus on a spot whilst waiting for the subject to go past. Both of these are covered in more detail later in this series.
Auto focus systems - blazing fast focusing to help you get your shot
Cameras nowadays have an amazing ability to help you accurately focus in an incredibly short time. Although manual focus definitely still does have a place in photography, most of the time you’ll use the camera in auto focus mode. All modern cameras, both DSLR and Compact cameras, have a number of different autofocus modes that can be used to handle two basic different situations – focus on a subject that isn’t moving and focus on a subject that is moving.
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| Auto focus systems in modern day cameras are great in focusing in difficult situations. |
Many people leave their camera in the default auto focus mode, mainly due to lack of understanding what the other modes do. Here’s a brief explanation of different types of modes. Each camera will have different names for different modes and you’ll need to refer to the manual (no that’s not a dirty word) to see how to select the autofocus mode in your camera and the correct name for the different types referenced below:
FlexiZone / One Shot / AF-S / AF.S / S-AF – This is the default mode for many cameras and my personal favorite for most of my photography. Best used for static objects in pictures and uses a defined area or focal point on your picture, normally the center, where the camera will focus on. Often the focal point can be moved around the screen using either a menu option or via a button on the camera. Personally I find it quicker to leave the focal point in the center and focus on the subject, press the shutter button half way to lock the focus and then while keeping the shutter pressed half way move the camera to recompose my photo before fully pressing the shutter button to take the shot.
Once you press the shutter button half way the focus will lock onto the target within the focus area/point until you take the shot or release the shutter button. This is great when focusing on a static subject as it allows you to recompose the shot whilst keeping the shutter button semi depressed without losing focus on the subject.
Face detect – As the name suggests the camera’s autofocus system will look for human faces (or something that looks like a human face ) and lock onto it. It will track the face if it moves around the screen. Once you press the shutter button half way it will lock the focus on the face and will not continue to track the face if they continue to move. This is obviously great for using with people. With groups of people, the camera will try and select as many people as possible that are in focus, however the risk is that it may focus on the wrong person by mistake – but it doesn’t happen often.
Tracking or Predictive auto focus / AI Servo / AF-C / C-AF / AF.C – Tracks the subject that you focus on as they move towards or away from the camera until you take the shot.
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| Predictive auto focus can be useful when shooting fast moving subjects |
AI Focus / AF-A – On the Canon DSLRs this mode automatically switches between One Shot and AI Servo mode depending on if the camera senses movement.
Manual focus – I use manual focus in one of two scenarios (1) Macro photography along with a tripod because small movements can quickly throw the subject out of focus or can focus on the wrong part of the subject and (2) Low light photography when the camera finds it hard to automatically focus.
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| Manual focus is useful when shooting macro images |
Changing the Auto Focus Method
Each camera is slightly different, but generally uses a menu to select the focus method
On the Canon 5D MKII the focus method is accessed via the AF button and then selecting one of the three options
The Canon G12 uses the menu button to go to the picture tab and then you scroll through the various options
The Sony DSC-W170 also use the menu button to access the focus method, in this case it only has face detect with a few variations to prioritize children’s or adult’s faces.
Pre-Focus
One technique that’s useful when taking pictures of fast moving objects is called “pre-focus”. Pre-focus is where you focus on a spot where the subject you are shooting is going to pass so that you are ready to take the shot when the subject appears. Many sports photographers use this at sports events with fast moving subjects, e.g. car or bike racing, etc.
Figure 1: I focused manually on the place where the boarder was passing and then asked him to pass through the same spot
Figure 2: For this shot I had to have the model stand in the shot first and then take adjust the focus using a tripod. After getting the focus right and putting the camera into manual focus mode the model was able to run and leap over the spot where had previously stood.
Coming up...
Next week we are going to look at:
- Understanding ISO - knowing the point between the good, the bad and the ugly when choosing a the speed of the film/sensor
- White Balance - Dealing with Colorcasts and knowing how to work the colorcast to your advatage.
Please feel free to leave comments or questions below or email them to me.
