Hey, how’s it going, I’m Andy Jones and this is episode 64 of the Photography Q&A Podcast.
So last week I covered Aperture and Depth of Field, and this week it’s Shutter Speed and ISO.
If you are new to the podcast and just starting out on your photography journey, this episode isn’t the best place to start. Have a listen to the Exposure Triangle episode first, then last week’s episode on Aperture and Depth of Field, then listen to this one.
Ok, so let’s get started on Shutter Speed and ISO.
The reason you change these settings is to balance the Exposure Meter or Light meter. For this episode, we’ll call it the exposure meter.
So the first controller of light coming into your camera are the aperture blades in the lens, and the second is the Shutter. The shutter sits in front of the sensor and opens and closes to allow the light onto the sensor. It controls the amount of light by how long it’s open.
If your shutter speed is 200, that means the shutter is open for 200th of a second. Most cameras have shutter speeds that range from 30 seconds to 8000th of a second.
When you initially set your shutter speed you need to consider what you want to achieve.
I’ll give you two examples from each end of the spectrum.
Sports
If you are shooting sports you might want to freeze the action. To do this you will need a speed in the range of 500 to 8000. The faster the subject the faster the shutter speed needs to be.
But, if you want the image to convey the speed of the subject and capture movement, you can use a technique called panning. An example would be someone cycling by. You focus on the subject and keep the focus point on them as they pass in front of you. This will cause the subject to be in focus and the background to be blurred. The background being blurred conveys the feeling of movement.
Now to do this you don’t need a fast shutter speed. The camera is moving at the same speed as the subject, so you can use a much slower shutter speed. You can use speeds in the range of 50 to 125, it just depends on how much movement you want to capture. The slower the shutter speed the more motion blur you get.
The next example is…
Landscapes
Most landscape photographers use a tripod because they generally use slower shutter speeds. These are speeds that you are too slow to handhold the camera. Landscape photographers don’t, as a rule, go out in the midday sun. They want sunrise and sunsets, or extreme skies. So it’s most likely that there isn’t a lot of light available. Speeds of ¼ or ½ a second are commonplace.
If the subject has moving water and the aim is to give the water a misty ethereal look, speeds of 1 to 3 seconds are what's needed.
Now there are times when a landscape needs a fast shutter speed. An example is taking a photo of a coastline and trying to capture the waves breaking on the rocks. You could use a slow shutter and the water will look soft and misty, or use a speed of over 1000 to freeze the waves.
Ok, so those are the two extremes, one needs fast shutter speeds and the other slow. Next, I’ll explain ISO and then how you need them to work together before taking the photo.
ISO stands for International Organization for Standardization. The sensor is made up of pixels that capture the light. The ISO numbers tell you how sensitive the sensor is to light. The higher the number the more sensitive it is.
When you change the ISO from 100 to 200 or higher, some of the pixels on the sensor are turned off. This makes the sensor more sensitive to light allowing you to get more light in your photos in darker situations.
The downside is when you use high ISO numbers like 1600 and above the image will be grainy.
Always start out at your lowest possible ISO setting. On most cameras, it’s 100, or it might be 50, 64, or 32. Whatever it is start low.
So all the settings, that is Aperture, Shutter Speed, and ISO need to work together to create a perfectly exposed photo.
This is where the exposure meter or light meter comes in to make your life easier.
You can see the exposure meter in the viewfinder or on the rear LCD screen. If the marker is on the minus (-) side it’s under-exposed, not enough light. If it’s on the plus (+) side it is over-exposed and has too much light. You need to balance this meter in the middle.
So let's say you’re taking a portrait.
You chose an aperture of f/4, ISO100, and shutter speed of 1/250.
The meter marker is at minus 1 (-1). You need to add 1 stop of light.
The aperture of f/4 gives a perfect depth of field for this portrait so you don’t change it.
To get 1 stop of light you could change the ISO to 200, or reduce the shutter speed to 1/125.
Changing the shutter speed won’t cause any problems.
Changing the ISO will make the image slightly more grainy. Although it will be hardly noticeable.
So you could choose either option and get a perfectly exposed image.
So let's try that again.
You chose an aperture of f/4, ISO100, and shutter speed of 1/125.
The meter marker is at minus 2 (-2). You need to add 2 stops of light.
The aperture of f/4 gives a perfect depth of field for this portrait so you don’t change it.
To get 2 stops of light you could change the ISO to 400, or reduce the shutter speed to 1/30.
Changing the shutter speed to 1/30 of a second is too slow for you to hand hold. It’ll cause camera shake.
Changing the ISO100 to ISO400 will make the image more grainy.
You could just change the ISO to ISO 400 or you could gain just 1 stop of light with ISO200. Then get the other 1 stop from changing the shutter speed to 1/60 of a second, but only if you are comfortable at that speed.
Let’s do one more. A landscape image.
This will be on a tripod.
You set the aperture to f/11, ISO100, and shutter speed 1/15.
The marker is at plus 1 (+1) so the image is over-exposed, with too much light.
Again the aperture is perfect so leave it alone. The ISO100 setting can’t go any lower to reduce the light. So the shutter speed needs to be faster than 1/15 of a second. Turn the shutter speed to 1/30 of a second and the marker will be at the center of the exposure meter.
That’s it, once you know how to work out what depth of field you need, the aperture setting is pretty much set in stone. There might be situations you might need to change, but just make sure it isn’t too shallow.
Remember that each mark on the meter is one click on a dial, three clicks equal one stop. After a while it all becomes automatic, you won’t need to think about it.
I hope you understood all of that, if you have any questions you can find me on the Facebook group, there’s a link in the show notes.
That’s it for this episode, I’ll be back next week with more photo waffle. Bye