Digital Camera Lenses Tutorial

This little tutorial about camera lenses can help you add a lot more creative control to digital photography. Choosing the best lens for the task can turn into a complex trade-off between cost, size, weight, lens speed and image high quality. This tutorial aims to improve understanding by providing an introductory overview of concepts relating to image quality, focal length, perspective, prime vs. zoom lenses and aperture or f-number.

 Lens Elements & Image Quality
Optical aberrations happen when points of the image do not translate back onto single points after passing by means of the lens, causing image blurring, decreased contrast or misalignment of colors (chromatic aberration). Lenses might also suffer from uneven, radially decreasing image brightness (vignetting) or distortion. Try moving your mouse over every of the choices below to see how these can impact image top quality for extreme instances. Any of the above problems is present to some degree with any lens. Inside the rest of this tutorial, when a lens is referred to as having lower optical high quality than an additional lens, this is manifested as some combination of the above artifacts. Some of these lens artifacts may not be as objectionable as others, depending on the subject matter.

Influence of Lens Focal Length
The focal length of a lens determines its angle of view, and thus also how significantly the subject will likely be magnified for a given photographic position. Wide angle lenses have small focal lengths, even though telephoto lenses have larger corresponding focal lengths. Several will say that focal length also determines the perspective of an image, but strictly speaking, perspective only changes with one's location relative to their subject. If one tries to obtain the same subjects filling the frame with both a wide angle and telephoto lens, then perspective does indeed change simply because 1 is forced to move closer or further from their subject. For these scenarios only, the wide angle lens exaggerates or stretches perspective, whereas the telephoto lens compresses or flattens perspective.
Perspective control can be a powerful compositional tool in photography, and frequently determines one's selection in focal length (when one can photograph from any position). Move your mouse over the above image to view an exaggerated perspective as a result of a wider angle lens. Note how the subjects within the frame remain nearly identical-- for that reason requiring a closer position for the wider angle lens. The relative sizes of objects change such that the distant doorway becomes smaller relative to the nearby lamps.

The following table provides a overview of what focal lengths are required to be considered a wide angle or telephoto lens, additionally to their typical uses. Please note that focal lengths listed are just rough ranges, and actual uses might vary considerably; several use telephoto lenses in distant landscapes to compress perspective, for instance.

Other elements might also be influenced by lens focal length. Telephoto lenses are a lot more susceptible to camera shake since modest hand movements turn into magnified within the image, similar to the shakiness experience whilst attempting to look by way of binoculars with a significant zoom. Wide angle lenses are usually a lot more resistant to flare, partially due to the fact the designers assume that the sun is a lot more likely to be within the frame for a wider angle of view. A final consideration is that medium and telephoto lenses generally yield much better optical quality for similar price ranges.

CANON lenses notations:

  • EF - The EF lens mount allows all the Canon EF lenses to be used on any of the Canon EOS. EF stands for “Electro-Focus”: automatic focusing on EF lenses is handled by a dedicated electric motor built into the lens. All communication between camera and lens takes place through electrical contacts; there are no mechanical levers or plungers.
  • USM - Ultrasonic motor drive - EF lenses equipped with USM drives have fast, silent and precise auto focus operations, and consume less power compared to other AF drive motors. There are two types of USMs, the ring-type USM and the micromotor USM. Ring-type USM is always preferred because of its superior performance and efficiency, and it allows for full-time manual focus operations without switching out of AF mode.
  • IS - Image stabilizer - the Image Stabilizer (IS) counters camera movements and shakes by optically correcting such shakes with accelerometers and lens groups that move in relation to the shakes, thus minimizing or even eliminating minute vibrations from the image. A general rule-of-thumb to overcome such vibrations would be to set the shutter speed equal to or faster than the reciprocal of the lens focal length (e.g. 1/125s for a 100 mm lens). IS lenses can improve on this rule by up to three stops. That is, the same 100 mm lens could be used at 1/30s.
  • L - series lenses - top of the line Canon EF lenses are designated as L-series. L-series lenses have superior optical performance and are typically built with a solid construction to withstand constant use and harsh conditions. They can be recognized by a red ring around the front part of the lens. Most recent L lenses have sealing to help resist dust and water. L-series lenses are more frequently used by professionals and serious amateurs due to their high price and large mass.
  • EF-S - The lens mount is a derivative of the EF lens mount created for a subset of Canon digital single-lens reflex cameras with APS-C sized image sensors.

NIKON lenses notations:

  • Nikon F-mount refers to a lens mount developed by Nikon for its 35 mm SLR cameras
  • AF - auto focus designation, indicating focus driven by a motor inside the camera body.
  • AF-S - Auto focus-Silent. Uses a “Silent Wave Motor” (ultrasonic motor) to focus quietly and quickly. Similar to Canon’s “USM” technology
  • AF-I - Auto focus-Internal - driven by a coreless DC motor.
  • ED - “Extra-low Dispersion” glass incorporated to reduce chromatic aberration. “Super ED” glass has been introduced as well.
  • IF - Internal Focus - focusing is accomplished through the movement of internal lens groups, eliminating extension and rotation of the front lens element.
  • DX - Lens designed for Nikon DX format sensors. The image circle matches the smaller sensor area of Nikon’s digital SLRs. A vignetted image may be produced if used on a 35mm format camera, although some DX lenses cover the full 35mm frame at longer focal lengths.
  • VR - Vibration Reduction - uses a moving optical group to reduce the photographic effects of camera shake. Similar to Canon’s Image Stabilizer, Sigma’s OS
  • D - Distance/Dimension - indicated after the f-number number. It means the lens is capable of using Nikon’s 3D Matrix Metering on bodies that support it. The lens transmits focus distance information, which is incorporated into the camera’s exposure calculations.
  • G - Indicated after the f-number. G lenses do not have an aperture ring, and the aperture can only be controlled electronically by the camera body
  • GN - Guide Number - aides in making flash exposures on cameras without automatic flash metering.
  • Micro - Micro lenses are capable of high reproduction ratios for macro photography.
  • N - Indicates the Nano Crystal Coat, a new type of lens coating that originated in Nikon’s semiconductor division.
  • PC - Perspective Control - lens includes movements to control perspective and depth-of-field.


 

Updated Nikon related news:

Feed Informer is fetching feeds for the digest. Please wait. This digest is powered by Feed Informer.

http://site-connect.net/codythebest