Shutter Speed. Introduction. Lesson Four. A quick refresher:

Transcription

1 Introduction Last week we introduced the concept of the Exposure Triangle and the goal to achieve correct exposure in our images, in other words...the image has enough light to best show off our subject or scene, or create the effect that we desire. We covered two of the three elements of the exposure triangle Aperture and ISO. This week we re going to focus on the third element - shutter speed - and how we can use it in our images, both for obtaining exposure and for effect. The best place to start is by reviewing the exposure triangle from last week, and just quietly - I think we re going to have lots of fun with this lesson! :D A quick refresher: ISO is the measure of our camera s sensitivity to light. The higher the ISO value, the more light we get, The trade off is increased ISO brings grain into our image. Aperture value indicates how wide or narrow the lens opening is. It directly affects exposure and the trade off is the effect it has on depth of field (how much of your scene is acceptably sharp in front of and behind your focus point. o Low f stop value = large opening - more light - shallow depth of field o High f stop value = small opening - less light - deep depth of field Shutter speed is the length of time the shutter remains open after you press the shutter release, and this in turn determines how much light can enter the camera to create our exposure. The trade offs are a slow shutter speed will record motion, including camera shake, and a fast shutter speed will freeze motion.

2 All three of theses elements work together to create an exposure, and changing one means the others must also be adjusted in order to maintain the same exposure. Fortunately, shutter speed, aperture and ISO are standardised so that an adjustment of one increment of any one of them in either direction will let in or reduce exactly the same amount of light. This is very handy because when you take a shot, then adjust, you know how much your adjustments should affect the image. For example, say you take a shot at 1/100s, f/4 and ISO 100, and your exposure is perfect. Then imagine you decide you want a much shallower depth of field. You know then that if you adjust your aperture by three increments down to f/2.8, you need to compensate this adjustment by three increments using either shutter speed, ISO or both, and in doing so you will gain the exact same exposure. So if you gained perfect exposure with 1/100s + f/4 + ISO400, you will obtain the same exposure with 1/200s + f/2.8 + ISO400, or 1/160s + f/2.8 + ISO320, or one of a few other combinations.

3 Note: Each increment of aperture, shutter speed and ISO that are available to us on our cameras are known as 1/3rd of a stop, and each 1/3rd of a stop increases or reduces light by 1/3rd of the previous setting. This lesson will cover: Introduction to Shutter Speed Lenses & Shutter Speed Freezing Movement Capturing Motion Panning Shutter Speed and Low Light

4 An Introduction to Shutter Speed When the shutter opens and closes quickly, the sensor captures simply what it saw in that fraction of a second, and has the effect of freezing motion. However, when the shutter speed remains open for a longer period of time, the sensor captures any motion that takes place during this time period motion from both your subject and your camera - even slight camera shift if you re not a super steady hand (like me). Different effects work well for different images, and in this lesson we ll explore how to use shutter speed purposefully to create interesting movement and affect, and to avoid common mistakes caused by the incorrect use of shutter speed. How does Shutter Speed Work? As we mentioned before, shutter speed is the amount of time the shutter speed stays open, and we adjust our shutter speed either to control our exposure, or to achieve a certain affect. Shutter speed is measured in seconds, and then fractions of a second. 1/1000th of a second is very fast, compared with 1/10th of a second. Some cameras also allow very slow shutter speeds, such as 1-2 seconds and up to 30 seconds to shoot in very low light situations and at night. This is recorded on your cameras as 30s. Some cameras have bulb mode (B) and this lets you leave the shutter open for as long as you hold the shutter button down.

5 Below is an example of different shutter speeds and the effect of freezing or capturing motion.

6 Lenses and Shutter Speed When you re taking photos and you re holding the camera yourself, in order to avoid camera shake (the movement recorded by the camera during the act of pressing the shutter release) the general rule of thumb is to match your shutter speed to your lens length at a minimum. Example for a 50mm lens, aim for no slower than 1/50s. When using a mm lens, aim for 1/200. If you must use a slower shutter speed, avoid camera shake by using a tripod or secure your camera somewhere steady, such as the ground, a pile of books, or a fence post. Of course this is a guide only, as we all hold the camera differently and have differing levels of steadiness. I personally don t like to go below 1/125s on my 50mm lens. Additionally, all of the above assumes your subject is completely still and the only motion you are attempting to freeze is camera shake and the very minor (if any) motion of your subject. When you re photographing people, especially children, then you certainly want to increase your shutter speed to compensate for their natural movement to ensure your subject is nicely in focus. When photographing children I try and keep my shutter speed at 1/250s at a minimum. For action shots (faster movement such as walking fast or running), you ll need even higher shutter speeds again, to beautifully freeze movement.

7 Freezing Motion High shutter speeds are perfect for capturing motion and are especially fun for sports or any kind of action. However remember the trade off high shutter speeds capture less light, therefore in order to ensure correct exposure you ll need to capture that lost light in another way. In that instance, remember the exposure triangle - you will need to adjust either your aperture value or ISO to compensate for the light you lost when you increased your shutter speed. When shooting outdoors this shouldn t present too much of a challenge, due to the abundance of available natural light.

8

9 Capturing Motion Slow shutter speeds, when used purposefully, are probably one of the most fun and high impact effects you can use. It allows you to capture the moving lights on a freeway, the running streams of water, shooting star trails through the sky, and in landscape photography its what allows you to capture those perfectly still, serene looking images, where the water is completely smooth. Slow shutter speeds will start capturing motion anywhere from 1/20s and below, depending on how fast the object is moving. To avoid the camera shake that we ve discussed, slow shutter speeds are best suited for use with a tripod or similar. Look at the examples below and the shutter speeds that have been used to capture them.

10 Light Painting

11 Panning Panning is the act of capturing the movement of your background, whilst simultaneously keeping the subject in focus. This effect is certainly a little tricky, and takes some practice, but it s a very cool effect that you ll probably recognise from motorbike and car advertising shots. Its best to attempt this effect using a tripod that allows you to pan the camera, so that the only motion you re capturing is the background, and you ll avoid camera shake which takes the subject out of focus.

12 Photo Challenge Photo Challenge One The first challenge this week is to capture movement in an object with a slow shutter speed. It could be a spinning coin, your child (or partner) on their bike, a moving toy, a flag in the wind. Set your camera up on your table, a tripod, or a pile of books to ensure the camera is still in order you can capture only the movement of the object remember if you try and hold your camera for this challenge it will record any movement in your hands resulting in a blurry image for the wrong reasons. Here are some pointers: Set your shutter speed to 1/20s. Before putting your object into motion take a test shot to ensure your exposure is correct - your image should be neither too bright nor too dark. The slow shutter speed will let in lots of light, so you may need a higher aperture and lower ISO to ensure correct exposure (dependent of course on the available light). After you ve taken your first shots adjust the shutter speed up and down slightly to see which shutter speed gives you the best effect. If shooting indoors, aim to set up on the floor or a table about 45 degrees from a big window or door, or use your garage porch light that we covered in Lesson Two.

13 Photo Challenge Two The second challenge this week is to capture fast motion. I m going to suggest you use a liquid and then drop something into it, such as an ice cube, a piece of fruit (grape, strawberry, cherry). Set it up somewhere outside, or in your garage close to the entrance so there s plenty of light. You can capture this holding your camera, but if you prefer to use a tripod or prop your camera up, then that can help too! Set the shutter speed to at least 1/500s but go higher if you have enough light. Focus your camera on the liquid, and then ask someone to drop the object into the container of liquid. OR - photograph water coming out of a tap if you prefer... it will still be a great effect! It s best to use the rapid shots function (see the tutorial for how to do this). Select your favourite from Challenge One or Two and submit for critique.