F number cameracanon

Glasses with single vision correction lenses. They help with seeing either at a distance or near, depending on the wearer’s needs.

F-number lens

His first serious camera was the iconic Olympus OM10, with which he won the title of Young Photographer of the Year - long before the advent of autofocus and memory cards. Today he uses a Nikon D800, a Fujifilm X-T1, a Sony A7, and his iPhone 15 Pro Max.

Glasses with Transitions® lenses automatically darken in sunny conditions and become clear when it’s darker. This allows them to work as both eyeglasses and sunglasses.

An anti-reflective (also known as anti-glare) coating prevents reflections from appearing on both the inside and outside of your eyeglass or sunglass lenses. No reflections on your lenses means more light is reaching your eyes, which inevitably improves your vision.

So, how does the f-stop, or aperture, impact your image? Primarily, it influences exposure, though the effect depends on the exposure mode you’re using. In Manual mode, if you change the aperture without adjusting the shutter speed, your image will either become darker or lighter depending on your adjustment. In Aperture Priority mode, however, your camera automatically adjusts the shutter speed as you change the aperture, maintaining a consistent exposure.

The f-stop number actually refers to the size of the aperture opening, calculated by dividing the lens's focal length by the f-number. For example, with a 200mm lens, an f/4 aperture would have a diameter of 50mm (one-quarter of 200mm).

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Anti-reflective coating glasses lenses are practically invisible, so your eyes will look better and your stylish frames can take center stage.

F number camerafor beginners

Fstop symbol

Blue light filtering lenses filter blue-violet light (blue-violet light is between 400-455nm, as stated by ISO TR 20772:2018​ and can accelerate aging of the retina) emitted mainly by the sun outdoors and indoors through windows, plus some artificial light sources like digital screens and fluorescent lights.

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Even if you've never manually adjusted the f-stop on your lens or camera, you've likely come across this setting before. While it's possible to let the camera handle it automatically, mastering the f-stop is crucial if you want to fully control your photography.

So, the smaller the aperture, the longer the shutter speed you'll need in a given situation. You can observe this by setting your camera to Aperture Priority mode and adjusting the aperture; the shutter speed will change with each adjustment.

Glasses with lenses that help the wearer see things up close. Many people need reading lenses as they get older due to a common condition called presbyopia.

Extremely wide apertures can also be difficult to manage in bright conditions, as your camera may not be able to use a fast enough shutter speed to prevent overexposure unless you use an ND filter.

Both very small and very wide apertures have their challenges, so it's important to evaluate each scene to determine the most appropriate setting. Wide apertures are excellent for isolating subjects from their backgrounds, but they can lead to softer images due to an effect known as spherical aberration.

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He has written about technology for countless publications and websites including The Sunday Times Magazine, The Daily Telegraph, Dorling Kindersley, What Cellphone, T3 and Techradar.

f-number calculator

Ever hear these terms? Stopping down the lens or aperture simply means to make the aperture smaller, such as from f/8 to f/11. Opening up, meanwhile, means doing the opposite.

F-stop vs aperture

Progressive lenses are a type of bifocal lens that features a gradual change between near and distance vision correction. The premium version offers a wider field of vision.

No matter which mode you choose, adjusting the aperture will impact the depth of field. Depth of field refers to the range within a scene that appears in focus, and photographers often use medium to small apertures to achieve greater sharpness throughout the image. However, depth of field also depends on factors like where you focus within the scene.

F-stop chart

f-number formula

Chris George has worked on Digital Camera World since its launch in 2017. He has been writing about photography, mobile phones, video making and technology for over 30 years – and has edited numerous magazines including PhotoPlus, N-Photo, Digital Camera, Video Camera, and Professional Photography.

Also known as aperture size, the f-stop controls the amount of light that passes through the lens at a given shutter speed. All else being equal, a smaller aperture (like f/16) allows in less light than a larger one (like f/4), meaning it takes longer for the same amount of light to reach the sensor. It's similar to how an hourglass works: the size of the opening between the chambers determines how long it takes for the sand to flow from top to bottom.

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On the other hand, small apertures can make diffraction more noticeable, which can also soften images. These apertures are also more challenging when hand-holding the camera, as the smaller the aperture, the longer the shutter speed required—eventually making it difficult to hold the camera steady enough for sharp images. In such cases, a tripod or a good image stabilization system can be helpful.

Our 365-Day Product Guarantee allows a one-time replacement pair of eyewear within 12 months, if any defects in the material or workmanship are found that prevent you from enjoying your frames to the fullest.

One thing that often confuses beginners is that small physical apertures have high f-stop numbers like f/16 and f/22, while large (or "wide") apertures have low f-stop numbers like f/1.4 and f/2. The reason is that f/16 represents one-sixteenth, not sixteen, and f/4 represents a quarter, not four.

All single vision EyeBuyDirect lenses come standard with an anti-reflective coating. High-index lenses naturally reflect more light, so this is an important addition if you’re interested in thinner lenses.

Our 365-Day Guarantee means you’re eligible for a one-time replacement pair within 12 months of purchase if there are clear defects in material and workmanship — so be good to your glasses!