Showing posts with label Lens. Show all posts
Showing posts with label Lens. Show all posts

Lens Filters: What Are They and When Do We Need Them

Monday, 25 August 2014

Many lens filters in today’s digital society have been made redundant. Most cameras and/or post-processing tools now include features for correcting white balance, for softening, and for various special effects. But there are still some effects that simply cannot be reproduced without the use of filters. Here we give you an overview of the most essential filters that every photographer should learn to use.
lens filter guide“love story” captured by b-bee 

Using Lens Filters

A small filter may be applied to the lens to provide reinforcing or fun effects. Filters had their hay day when people where still photographing with film. Digital imaging had at that time not come that far, and we used different filters to get the desired effect instead.
For that reason, many associate the use of filters with a clear image manipulation. However the most common filters do not provide such drastic results. They are used simply to reinforce the individual effects, such as light phenomena.

Here are Some of the Most Common Lens Filters

Polarizing Filter
A polarizing filter is probably the most known and used of all filters, and not without reason. This filter works much like putting a pair of sunglasses in front of the lens. It eliminates reflections, glass, shiny surfaces and water, and thus enables you to photograph what is behind a window or under the water, rather than a surface full of reflections. Polarizing filters also contribute to greater contrast and more saturated colors, and they can make the sky darker, which is especially useful when photographing landscapes.
polarizer filter“Dubai Skyline” captured by Bella 
Polarizing filters work, however, only when you photograph your subject from an angle, not straight on. That is, if you stand right in front of a window and shoot, the filter may not be able to remove the reflections in the glass. Therefore, make sure you’re always shooting from an angle. There are two types of polarizers: linear and circular. Linear is used with older manual cameras, while the circular is used for cameras with auto focus.
UV Filter
A UV filter improves color reproduction and eliminates blur caused by ultraviolet radiation. Ultraviolet light is invisible to the eye and highly prevalent when shooting in hazy weather, mountainous regions, coastal areas and areas with very clear air. UV filters are colorless and do not require any extension of exposure time. It is recommended that UV filters be permanently mounted on the lens as a protective filter.
When you attach this filter on top of the lens glass, it is the actual filter that is exposed to any dust and scratches. It is much cheaper to replace a filter if you scratch or damage it, than to replace the entire lens.
When using a UV-filter, it is important to remember that the glass of the filter should have at least as good quality as the glass of the lens. Otherwise, the picture quality will be deteriorated.
ND (Neutral Density) Filter
A neutral density filter, makes it possible to shoot with slower shutter speeds or large apertures, even in very bright situations. This is because the amount of light emitted through the lens is reduced. This is useful if you, for example, want to photograph a waterfall in daylight, but still want the smooth effect of water in motion. ND filters are available in different strengths, depending on how much light you want to block out.
oregon-coast-neutral-density-filter“Sunshine” captured by Luke Detwiler
Another option is a graduated ND filter. This filter goes from dark to clear, with either smooth or sharp transitions. This filter is used, for example, when the foreground and background require different exposure. An example is when you photograph something dark under a bright sky. With a graduated ND filter, you can correctly expose the dark portion of the image without the bright portion being overexposed.
They are also used to reduce the contrast of the image. At sunrise, you may need to dim the sunlight a bit to reveal details in other areas of the image. There are also graded alternatives with colors, which can be used for special effects. Orange or brownish versions can provide atmospheric skies in the pictures.

DSLR Camera Lenses and Their Abbreviations

Saturday, 26 October 2013

For those of you who want to learn what these abbreviations are about, I have compiled a list of the terms used, what it stands for and of course what it will actually do for you or avoid.

General Abbreviations

Before we get into the nitty gritty of why they are all different, let’s look at the commonalities. There are three common terms to describe SLR lenses and these are simple to grasp and relate purely to more creative and performance functions.
camera lens abbreviations“lens” captured by Jonathan (Click Image to See More From Jonathan)
Focal length: The scope of the scene captured example 16-35mm. A lens which covers an area of 16mm (relatively wide) zooming in to 35mm.
Maximum aperture: The maximum speed at which the lens can let in light. eg f/2.8 or f3.5 – 5.6
If the lens has only one number then that is the maximum aperture possible.
If the lens has 2 numbers then these are the maximum apertures possible dependent upon the focal length the lens is set to.
The lower the number the wider the lens aperture and the faster it lets in light. (see my forthcoming article on the law of reciprocity)
AF/MF: Switch between Auto Focus and Manual Focus
Canon Lens Abbreviations
Terms to describe Canon lenses
Canon produce an extremely wide range of lenses for their EOS cameras. This married with the ranges produced by Sigma, Tamron and Tokina gives Canon owners an enormous range of Canon Fit SLR Lenses. The abbreviations used by Canon are as below.
EF: Electronic Focus. Lens mount fits the entire Canon EOS DSLR range.
EF-S: As above but only fitting the APS-C sensor digital SLR such as the 20D, 30D, 40D, 50D and 300D, 350D, 400D, 450D, 500D. The S stands for “short back focus,” meaning that the back of the lens is much closer to the CMOS (CCD if you like) than with EF lenses.
USM: Ultrasonic autofocus motor. Two types. USM micro-a direct replacement for the systems on older FD motors and ‘Ring USM’ with manual override.
DO: Diffractive optics. A technology allowing Canon to produce shorter physical length lenses.
TS-E: Tilt-shift lens used for perspective correction in photography, usually in architectural work to alter converging lines and depth of field. Similar to ‘Sinar’ camera.
L Lenses: Canon professional with higher optical quality and not specifically functionality. Usually white in colour. All L series lenses have a red ring on the outside..
MP-E: Macro Photo Electronic. Lenses designed for macro with an electronic aperture control function.
IS: Image Stabilisation, A system designed to reduce hand shake. Nikon version is called VR (Vibration Reduction) and Sigma one is OS (Optical Stabilisation).
Nikon Lens Abbreviations
Describing Nikon Lenses
Nikon produce a large range of lenses with their own specific acronyms. Sigma, Tamron and Tokina also make Nikon Fit SLR Lenses making the selection almost equally as wide
AF DC_ Nikkor Lenses: Defocus-image Control adjusting spherical aberration and thus the blur giving rounded blur effect used for portraits.
CRC (Close-Range Correction): Fot fisheye, wide-angle, Micro, and limited medium telephoto, offering higher quality at closer distances.
DX Nikkor: optimised for bodies with smaller sensors.
ED: Extra-low Dispersion glass. Superior sharpness and colour, correcting blue and red light travel.
IF: Internal Focusing. Lens length remains unchanged
Macro: suitable for close up focusing.
G: Aperture adjusted by the camera body.
Nano Crystal Coat: non-reflective coating for clearer images.
VR: Vibration Reduction: Nikon’s version Image Stabilisation to cur down the effects of hand shake.
PC-E: Perspective Control for architectural photography.
RF: Rear Focusing for smoother auto focus..
Silent Wave Motor: Silent AF
Sigma Lens Abbreviations
Acronyms for Sigma lenses
EX: Sigma’s professional lenses.
DG: For full frame bodies
DC: For APS-C bodies.
ASP: Aspherical lens.
APO: Apochromatic lens. Unique to Sigma and for chromatic aberration.
OS: Optical Stabilisation.
HSM: Hypersonic Motor. Silent AF.
RF: Rear focus..
IF: Inner focus so lens physical length is fixed reducing hand shake on longer focus shots.
DF: Dual focus. Does not rotate during AF.
Conv: Used with Sigma teleconverters.
Tamron Lens Abbreviations
Tamron Lenses described
ASL: Aspherical
AD: Reduces chromatic aberration..
Di: Full frame
Di II: Cropped Frame.
IF: Internal focus.
LD: Low Dispersion Glass to reduce chromatic abberation
Macro: Designed to focus on closer subjects
SP: Super Performance.
XR: Extra Refractive Glass for improved optical results.
VC: Vibration Control as Canon’s IS, Sigma’s OS and Nikon’s VR.
 

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