ApertureIf you can master aperture you put into your grasp real creative control over your camera. In my opinion – aperture is where a lot of the magic happens in photography and changes in it can mean the difference between one dimensional and multi-dimensional shots. What is Aperture?Put most simply – Aperture is ‘the opening in the lens.’ The iris of the lens that controls the size (diameter) of the aperture is called “diaphragm” in optics. The sole purpose of the diaphragm is to block or stop all light, with the exception of the light that goes through the aperture. When you hit the shutter release button of your camera a hole opens up that allows your cameras image sensor to catch a glimpse of the scene you’re wanting to capture. The aperture that you set impacts the size of that hole. The larger the hole the more light that gets in – the smaller the hole the less light. Aperture is measured in ‘f-stops’. You’ll often see them referred to as f/number – for example f/2.8, f/4, f/5.6,f/8,f/22 etc. Moving from one f-stop to the next doubles or halves the size of the amount of opening in your lens (and the amount of light getting through). Keep in mind that a change in shutter speed from one stop to the next doubles or halves the amount of light that gets in also – this means if you increase one and decrease the other you let the same amount of light in – very handy to keep in mind). One thing that causes a lot of new photographer’s confusion is that large apertures (where lots of light gets through) are given f/stop smaller numbers and smaller apertures (where less light gets through) have larger f-stop numbers. So f/2.8 is in fact a much larger aperture than f/22. It seems the wrong way around when you first hear it but you’ll get the hang of it. Smaller number = bigger aperture = more light & bigger number = smaller aperture = less light Depth of Field & ApertureDepth of field is a by-product of aperture. The size of aperture has a direct impact on depth of field. There are a number of results of changing the aperture of your shots that you’ll want to keep in mind as you consider your setting but the most noticeable one will be the depth of field that your shot will have. Depth of Field (DOF) is that amount of your shot that will be in focus. Large depth of field means that most of your image will be in focus whether it’s close to your camera or far away. For example the landscape shot above has an aperture of f/16 and the result is that both the mountain in the background and the boats in the foreground remain in focus. Small (or shallow) depth of field means that only part of the image will be in focus and the rest will be fuzzy. Aperture has a big impact upon depth of field. Large aperture (remember it’s a smaller number) will decrease depth of field while small aperture (larger numbers) will give you larger depth of field. It can be a little confusing at first but the way I remember it is that small numbers mean small DOF and large numbers mean large DOF. Different Styles use Different AperturesMost landscape photography you’ll see small aperture settings (large numbers) selected by photographers. This ensures that from the foreground to the horizon is relatively in focus. On the other hand in portrait photography it can be very handy to have your subject perfectly in focus but to have a nice blurry background in order to ensure that your subject is the main focal point and that other elements in the shot are not distracting. In this case you’d choose a large aperture (small number) to ensure a shallow depth of field. Macro photographers tend to be big users of large apertures to ensure that the element of their subject that they are focusing in on totally captures the attention of the viewer of their images while the rest of the image is completely thrown out of focus. Aperture on LensesEvery lens has a limit on how large or how small the aperture can get. If you take a look at the specifications of your lens, it should say what the maximum (lowest f-number) and minimum apertures (highest f-number) of your lens are. The maximum aperture of the lens is much more important than the minimum, because it shows the speed of the lens. A lens that has an aperture of f/1.2 or f/1.4 as the maximum aperture is considered to be a fast lens, because it can pass through more light than, for example, a lens with a maximum aperture of f/4.0. That’s why lenses with large apertures are better suited for low light photography. All lens apertures can be narrowed as much as you want. For example, every lens on the market today – regardless of manufacturer – can be set to f/16. However, the reverse is not true: every lens on the market cannot be opened up to f/1.4. The limit to how wide the lens can open is called the maximum aperture. A lens with a wider maximum aperture lets in more light. The minimum aperture is not that important, because almost all modern lenses can provide at least f/16 as the minimum aperture, which is typically more than enough for everyday photography needs. *Note that most lenses are at their sharpest around f/5.6 or f/8. However, many photographers are willing to trade some sharpness for the subject-isolating effects of a wider aperture. There are two types of lenses: “fixed” (also known as “prime”) and “zoom”. While zoom lenses give you the flexibility to zoom in and out (most point and shoot cameras have zoom lenses) without having to move closer or away from the subject, fixed or prime lenses only have one focal length. Due to the complexity of optical design for zoom lenses, many of the consumer lenses have variable apertures. What it means, is that when you are fully zoomed out, the aperture is one number, while zooming in will increase the f-number to a higher number. For example, the Nikon 18-200mm lens has a variable maximum aperture of f/3.5-f/5.6. When zoomed fully out at 18mm, the lens has an aperture of f/3.5, while when fully zoomed in at 200mm, the lens has an aperture of f/5.6. The heavy, professional zoom lenses, on the other hand, typically have fixed apertures. For example, the Nikon 70-200mm f/2.8 lens has the same maximum aperture of f/2.8 at all focal lengths between 70mm and 200mm. Why is this important? Because larger maximum aperture means that the lens can pass through more light, and hence, your camera can capture images faster in low-light situations. Having a larger maximum aperture also means better ability to isolate subjects from the background. Next will be ISO
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AuthorPhotographer & animal lover with a barn full of rabbits and a cat. Archives
January 2021
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