How does ISO affect exposure of an image?
Photography and the science of light continues with ISO. ISO is part of the Exposure triad or triangle, and works with Aperture and Shutter Speed to determine how your image is exposed. ISO in a nutshell is how sensitive your camera is to the light. I have already written about Exposure, Aperture, and Shutter Speed.
A lower ISO- 100 means the camera sensor is less sensitive to light. This setting is used in bright light situations to prevent overexposure. Bright midday sunlight, settings with bright light reflecting snow, etc. are times to use a lower ISO. Higher ISO settings are for situations with less light; cloudy days, dusk, when the snow is setting, nighttime, and indoors where there isn't a lot light.
Increasing the ISO can work well in low light situations to allow you to use a faster shutter speed and smaller aperture to get good crisp focus and deeper depth of field. However, Using a higher ISO can increase the "noise" in your image, making it grainier and foggy looking.
Below you can see the same shot with the only setting changed being ISO. I started with a low light situation with no flash. I wanted to show how increasing ISO increases the light in your image. If you enlarge each image, you will notice the increase grain in the photo as the light increases as well. My settings were f1.8, ss 1/60 and I adjusted ISO from 100 up to 6400.
I am an Amazon Affiliate. Blogging and sharing information takes a lot of time and effort! So if you are so inclined, follow my link to learn more about Exposure on Amazon! The link below will take you to a search for a huge selection of books all about photography exposure, aperture, shutter speed, and ISO.
How does shutter speed work?
The shutter speed on your camera can do several different things. It can affect the quality of the focus in your image. It can allow more or less light into your image. It can show motion and action. Or it can freeze a moment in time. Learning to adjust your shutter speed to affect the Exposure of your image can be tricky for beginners, but I am going to share some important ways shutter speed work for your image. If you are interested in Exposure and how the different pieces of the Exposure triad work, you can read more in my post Exposure: A Basic Explanation for Beginners. I give a basic tutorial of aperture in Aperture: A Basic Explanation for Beginners.
How Shutter speed affects Exposure
Exposure is determined three things:
In the examples below you will see a difference in the vibrancy of color and depth of color, just by speeding the shutter speed from 1/250 to 1/640. This was a bright clear afternoon. Even with a shutter speed of 1/250 on the left, the image appears washed out and less vibrant. By speeding my shutter speed to 1/640, I achieved more vibrant and deeper color.
What else does Shutter speed do?
Fair question. It's easy to understand that if you have something moving fast and you want to "FREEZE" that motion, You will speed up your shutter speed to freeze the motion. If you want to show motion and have a motion blur, you will slow your shutter speed.
I typically try to use at least 1/125 shutter speed and normally 1/250 shutter speed for portraits. It helps get a clean crisp focus with less motion blur.
Below are some shot I took with a 1/125 shutter speed because I was shooting objects that will move quick! ANIMALS AND KIDS. I wanted to Freeze them, before they moved! All of these shots were inside with indoor lighting. So, with my aperture opened up to let in light, I was able to use a faster shutter speed to compensate for wanting a sharp focus on my moving targets! For full disclosure, I did use on camera flash for these as well. Notice that bokeh or shallow depth of field? That's because of the wide open aperture. The two of my sweet baby boy Teller, were shot with a 35mm AF-S Nikkor f1.8 lens. My handsome nephew's picture was taken with an 85mm AF-S Nikkor f1.8. I rented both of these lenses from Lensrentals.com. You can read about my experiences renting lenses on these posts HERE.
Full disclosure: The links above for my amazon affiliated link. Blogging and keeping this adventure going is time consuming and I decided if I could make a penny or two, then what the heck? Links will be for items I have used or want to use and review! Thanks for using my links! I appreciate the help!
Focus and light
Photography is a science of light. How much light, for how long, and from where, determines the exposure of your image. And exposure is the the base of your image. There are loads and loads of explanations of aperture, shutter speed, and iso and how they affect exposure. I cover Basic Exposure in my post Basic Exposure for Beginners. Here is my take on APERTURE.
Aperture is set in f stops. Aperture goes as wide open as 1.2 and as closed 32. The aperture you are able to shoot with will vary depending on the lens. The wider open the aperture, the more light gets in to your camera for the image. Conversely, the smaller the aperture, the less light will get in to your to you sensor. Each FSTOP higher closes the hole smaller and smaller. It can get kind of confusing when starting out, because people may refer to using a "large" aperture meaning they used a small f-stop number which makes for a larger opening. F 1.8, which is the most open setting on my favorite 50mm prime lens, is as large an opening as that lens will open. The graphic above actually starts in the upper left corner with a "higher" or smaller aperture f stop, and ends in the bottom right corner with a "lower" or smaller aperture.
Aperture and focus
Aperture basically determines how at what distance your lens will focus and how far it will focus. For example, If you are shooting a your kids in front of the Grand Canyon, you probably want your kids smiling faces in focus and a large portion of the Canyon, too. You want to be able to see where your kids were at the time of the picture. A smaller opening in the aperture will make for a longer depth of field. And remember, smaller aperture means larger number when changing your settings.
Lower f stop numbers mean a shorter depth of field. Which in the example above would mean that your kids faces would be in focus, but the background behind them would be more and more blurred the further away they were from the subject.
Below I have some examples, where the only setting I changed was the aperture or f stop. Notice the subject is the dark duck. I wanted these pictures to have the back lighting so it would stick out how the background was being blurred and sharpened using the aperture. I didn't worry about lighting my subject at this point.
I shot these with a kit lens 18-55mm becuase I wanted to use a lens that a beginner would most likely have. You can see an even stronger difference with lenses that will open up to larger apertures. All settings stayed the same except adjusting aperture. Notice the stronger difference in the lack of focus of the background from image one, to the more focused back ground of image 6.
Aperture and light.
You will probably notice, that when the aperture is larger larger, the image lightens. That's because more light is getting in the camera. This is one of the ways you can lighten your image in dark situations, just keep in mind that this blurs objects and scenery that are not the same distance from your camera, because it shortens the depth of field.
The opposite is also true, by decreasing the size of the aperture, I can decrease the amount of light on a bright sunny day. However, this would not be the optimum way of doing this by itself if I were taking portraits or wanted a nice bokeh, because it will also bring my my background into clearer focus.
What did you like? What was confusing? What are you ideas? Let me know!
What is exposure?
You may be asking "How do I get the right exposure in my pictures? How does exposure work? How does aperture work? How does ISO work? How does Shutter Speed work? What do I do now that I have this big fancy camera?
Don't worry, I asked the same questions. Everything I know is from trial and error. Lots and lots of errors. I mean LOTS. I watched videos on youtube, read tutorials, pinned 50 blue million tips and tricks on photography. By the way, just pinning them does no good. You kinda have to go read them and put them into practice........
Anyway, I prescribe to the ideology that if you really want to learn you read it/see it, do it. teach it. So let me pass on what I have learned!
Photography is a science of light
Photography is all about light. How much light, for how long, and how sensitive your camera is to that light, determines the exposure of your image.
How much light is determined by Aperture.
How long the light is allowed in is determined by Shutter Speed.
How sensitive your camera is to light is ISO.
The Exposure Triad
All three settings can be manipulated depending on the type of picture you are taking. Faster shutter speeds are used for action shots like your son's basketball game. For this picture you probably want to open the aperture for more light and increase your ISO because basketball games are typically inside and the lighting may be poor. However, if you want a little motion blur you may slow your shutter speed just a bit.
Increasing your ISO can be helpful indoors, or on really dark gloomy days. Just be aware of your camera's limitations. Some entry level DLSR's are quite good at mid range ISO settings. But really high ISO's are normally best left to upgraded models.
Aperture is also good for increasing or decreasing your exposure. Just be aware of your lens Aperture capabilities, and pay attention to how much detail you want in your foreground and background.
The links below will be added as I publish each individual post!
I would love some feedback! What made sense? What was confusing? What are your ideas for explaining exposure?
Wife, daughter, aunt, nurse, biker chic, aspiring photographer, pretend gourmet chef. That's me! I'm living the Just Peachy Life. This Blog will now be more dedicated to photography and the art form that speaks to me the most. I am moving the lifestyle and home-life posts to the Living the Just Peachy Life Blog to separate the two! Read more about me and _Living the Just Peachy Life!
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