The angle of view of a lens changes according to the size of the sensor in the camera. A smaller sensor captures a narrower angle of view and makes it look as if the lens has a longer focal length. So in addition to the actual focal length, the manufacturers will usually quote the ‘effective’ […]
The lens is a fundamental part of any camera. It's what creates the image on the camera sensor (or film). Some cameras have a fixed, non-removable lens while others offer interchangeable lenses. Your choice of lens has a major impact on the appearance of your pictures, including the lens's focal length (angle of view) and its aperture setting (which you may or may not be able to adjust). At a simple level the lens is just the thing on the front of the camera, but on a more advanced level lenses open up a whole world of photographic choices, buying decisions and technical comparisons.
Here's a selection of further lens-related topics
An optical effect in some lenses where straight lines come out slightly bowed. You often see ‘barrel distortion’ with wideangle lenses or ‘pincushion distortion’ with telephoto lenses at their longest zoom setting. More expensive lenses tend to have less distortion but, generally, the longer the lens’s zoom range the more likely you are to see […]
Zoom function that comes from blowing up the central part of a digital image, not by increasing the magnification of the lens. Digital zooms produce lower resolution and less detail, despite what the makers say.
Mechanism inside a lens which uses interlocking metal leaves, or ‘blades’, to produce a variable-sized aperture within the lens. This is used to control the amount of light passing through and hence the exposure.
Usually you view the scene with the camera lens wide open and it only stops down to your chosen aperture the moment you press the shutter button, so it’s hard to judge just how much depth of field the final photo will have. The depth of field preview stops the lens down to the taking […]
Depth of field is the near-to-far sharpness in a picture. If both foreground and distant objects are sharp, there’s lot’s of depth of field – this shot is a good example. If only the subject is sharp and the foreground and background are blurred, it’s shallow d
Used to work out the effective focal length of lenses on cameras which don’t have full frame sensors. You multiply the actual focal length by the crop factor to get the effective focal length. The crop factor of an APS-C camera is 1.5, so a 50mm lens has an effective focal length of 75mm.
This is a Japanese word to describe the particular visual quality of out of focus areas in a picture. You might think it hardly matters what things look like when they’re out of focus, but there’s a bit more to it than that. ‘Bad’ bokek produces unnatural-looking outlines and highlights, while ‘good’ bokeh looks ‘creamy’, […]
The adjustable hole in the lens diaphragm is created by a set of overlapping metal leaves, or ‘blades’. The greater the number of blades, the rounder the hole created and the better the lens’s ‘bokeh’ in out of focus areas. Aperture blades are often curved, too, to enhance that circular shape.
This is the adjustable hole in the lens diaphragm that controls how much light passes through the lens and is used to adjust the exposure. Aperture setting values are the same across all cameras and lenses, and here’s a part of the series: f/2.8, f/4, f/5.6, f/8, f/11 – though the theoretical aperture range is […]
These are optical flaws produced by camera lenses and which are largely unavoidable except in the most expensive or the simplest lens designs. They include distortion, chromatic aberration (colour fringing), vignetting (corner shading) and edge softness.