The good news: there are plenty of zoom lenses with constant maximum apertures. Variable max aperture zoom, exposure settings constantly change as you zoom in and out. Photographers who control their cameras manually. Zoom lenses like this are a real problem for professional Somewhere in the middle of the zoom range (30mm) you'll get a maximum aperture number somewhere in the middle - say, f/4. At 55mm the maximum aperture narrows to f/5.6.The reason that thereĪre two numbers is because your zoom lens has a variable maximum aperture: The maximum aperture of a prime lens is straightforward: there's only one.īut with some zoom lenses, there can be TWO maximum apertures.Įxample: you've got a standard kit lens that came with yourĭigital camera and it's an 18-55mm f/3.5-5.6 zoom. Wait one second though.in some of these examples there are two numbers instead of one - what's up with that? Variable vs. That's pretty much the same for all lenses. Really no point in marking the MINIMUM aperture on the lens, because Now: these indicate the maximum aperture of the lens. The first set of numbers represent the focal length or focal length range.īut it's the second set of numbers we're most interested in right If you've been comparison shopping for lenses, you've probably had to wade through a whole lot of numbers. How to Tell the Maximum Aperture of a Lens Reduce the depth of field as much as you can with a wider aperture. If you have a lens with a maximum aperture of f/5.6, you can't Nature and portrait photographers use this all the time to reduce the impact of a busy background. Notice that theīackground is completely out of focus even though the turtle's head in the This shot was taken with a lens set to f/3.2. Take awhile), I will just refer to the photographic example at right. Without getting into a discussion on depth of field (that could Lenses with wide maximum apertures have shallow depth of field. Here's a graphic that shows the relationship between the opening of the lens and the aperture number: Larger Aperture Number (22) = Narrower Aperture = Less Light.Smaller Aperture Number (2.8) = Wider Aperture = More Light.That's because the numbers are the inverse of what you'd expect: This scale has completely confused many beginning photographers. There is a standard scale for aperture numbers, and it looks like this: The aperture of your lens works exactly the same way: it's aĬircular opening in the lens, and you have control over the size of the If you crank the window wide open tons of light spills into the room, and if you narrow it down then only a small beam gets in. There's a crank inside the room that lets you adjust the size of Imagine that you're standing inside a dark room with a circular However, before we can do that we have to start by talking about plain old aperture. So let's talk more about maximum aperture and how it differs from lens to lens. So you want to be sure before you dip into your wallet that you really NEED that wide opening and that you'll leverage it often. It's possible to spend several hundred more on a lens with a wider opening. Unfortunately there's a cost issue here: the wider a lens opens, the more it costs. I should just run out and get a lens with a super-wide opening and then I can take pictures whenever and wherever I like! Since light is the foundation of every photographic image, the more that the lens lets through, the more flexibility you have to take pictures in all kinds of available light - from bright sunlight to dim twilight.Īha! you say. Not all lenses are created equal: some can open up much wider than others and the ones that open up wider can let a lot more light through onto the sensor.
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