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Lens Elements and Groups
When shopping for camera gear, you've undoubtedly encountered listings detailing how many "elements" and "groups" certain lenses have. They generally don't come right out and say it, but such listings often imply that more is better.


Lens elements
Techniques Glossary Lens elements
The individual pieces of glass that form the overall optical construction. Most lenses have between four and eleven elements to bend the light rays to ensure a perfectly formed image appears on the light sensitive surface, such as a film or CCD.

LENS ELEMENTS & IMAGE QUALITY
All but the simplest cameras contain lenses which are actually comprised of several "lens elements." Each of these elements directs the path of light rays to recreate the image as accurately as possible on the digital sensor.

Lens elements.
5. Fine-tuning the Light
With a lens on the front of the camera, you can choose between having an image that's in focus or one that's out of focus but there really is no in between.

7 lens elements arranged in 5 groups including 2 aspherical elements
Micro four thirds mount
Closest focusing distance of 0.66' ...

" } , { "Title" : "AS" ,"GlossaryIcon" : { "Height" : "" , "Width" : "" } ,"HideInGlossary" : "1" ,"Summary" : "AS stands for Aspherical lens elements. This type of lens utilizes non-spherical surfaces on either one or both sides of the glass in order to eliminate certain types of lens aberration.

lens barrel - The tube that contains the ~.
lens cap - Hard, protective cover that clips over the front lens element when the lens is not in use.
lens coating - A microscopic antireflection coating applied to lenses that reduces flare and increases contrast.

A layer or multiple layers of thin anti-reflective materials applied to the surface of ~ to reduce light reflection (flare) and increase the amount of transmitted light.
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Sometimes applied to an iris diaphragm whose blades operate between ~. SHUTTER, FOCAL-PLANE-A shutter located near the focal plane and consisting of a curtain with a slot that is pulled across the focal plane to make the exposure.

However, its not always easy to tell where the ~ are. Check with your housing manufacturer for the best alignment.
You can use ports made out of optical glass or acrylic.

Glass is the most common material used to construct ~, due to its good optical properties and resistance to scratching. Other materials are also used, such as quartz glass, fluorite,[3][4][5][6] plastics like acrylic (Plexiglass), and even germanium and meteoritic glass.

Like the COOLPIX S3600, the Sony W830's lens is optically stabilised - the ~ are physically moved to counteract camera movement allowing you to shoot hand-held at slower shutter speeds and still get sharp results.

ED glass and hybrid aspherical lens elements minimize chromatic aberration, astigmatism and other forms of distortion, while ensuring high resolution and contrast
Incorporates a compact SWM (Silent Wave Motor) for quiet focusing ...

So the zoom physically moves in and out shifting the glass ~ inside the lens barrel to various positions to render the mathematical formulas necessary to create a series of lenses in a variety of focal lengths. Whew.

Schneider lenses of particular note include the Super-Symmar XL series with their aspherical lens elements. The 110mm f/5.6 Super-Symmar XL lens is extremely popular, and often listed as a "favorite" lens in many a photographer's arsenal.

Glass with ED properties indicating special rare earth glass or special formulated glass that limiting or correcting of light rays passing through the ~ to achieve all spectrum of colours to falls on the same plane of focus - especially the Red and Blue spectrum and is usually more ...

Zoom lens can have as many as 18 ~ but too many ~ is bad for image quality due to light refraction and formation of flare between the many ~. So most manufacturers will try to limit the design to between 14 to 16 elements.

COMPOUND LENS - A lens made up of two or more ~.
COMPRESSION - Image files containing all the information recorded on a digital camera's sensor can be quite large. "Compression" results in a smaller file that contains almost all the same information.

However, a teleconverter does contain ~. A teleconvertor increases the focal length of a lens, but it does not change the minimum focus distance. This results in an increase in magnification.

Three UD (Ultra-low Dispersion) glass ~ correct chromatic aberrations and floating elements ensure sharp definition at all subject distance. A ring USM provides silent AF and full-time manual focusing.

It has 2 clear ~; the front lens is the cornea which is fixed, and the flexible lens just behind the pupil which changes shape as we focus. There is a fluid filled cavity between the cornea and the lens. The eye itself is filled with a clear jelly like fluid called vitreous humor.

Reflected light; from ~, sun, metal, etc. Appears as non-uniform haze or bright spots on the film or digital frame, often taking the shape of the aperture, generally caused from shooting towards the light source.

Don't worry about things like the number of ~, type of glass used, or presence of aspheric elements. These can be indicators of a good lens, but too many ~ can also be a sign of lazy design.

The new lens has been engineered for the ultimate in optical performance through the use of two fluorite ~ for improved quality and reduced chromatic aberration. Helping photographers in the field, Canon has reduced the overall weight of the lens by a substantial 28 percent from 189.

The final solution to cleaning fungus from ~ when all else fails seems to be toothpaste. My "UG" Nikkor-P 105/4 bellows lens was giving me decidedly foggy images.

6L is an interesting lens in that, while it's technically an L series lens with fluorite and UD ~, it doesn't have the tough build quality of a typical L series lens sold today.

Cause: Front and/or rear ~ dirty. Solution: Clean with lens tissue and cleaning fluid. Use one drop of cleaning fluid on a tissue and clean lens in a circular motion starting from the center.
Cause: Low quality UV or Sky light filter. Solution: Remove filter or replace with a better one.

This is a shutter that sits between two of the ~, typically somewhere in the middle of the lens in a mechanism that also incorporates the iris diaphragm. On a mechanical camera, its speed is usually set on the lens itself.

Flare
Reflected light from ~, metal, etc. Appears as a non-uniform haze or bright spots on the film. Usually occurs when bright light (such as the sun) enters the lens.
Flash
Artificial light source. Usually camera mounted but also larger studio models called strobes.

Cheaper lenses, especially those that come built into a compact camera, can often contain plastic ~. This is a big deal for people searching for perfect quality because light doesn't travel through plastic as well as it travels through glass.

-Supplementary lenses - additional ~ used with the standard camera lens to provide a new focal length.
-Surface development - development process in which the image forms primarily on the surface of the emulsion and then penetrates deeper.

In a zoom lens, you can move different ~ back and forth. By changing the distance between particular lenses, you can adjust the magnification power -- the focal length -- of the lens as a whole.
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Lens coating
Transparent coated on ~ that helps reduce reflections and flare to improve image contrast.
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Zoom lenses contain more ~ than a fixed-focal length or prime lens, and therefore aren't quite as sharp. Naturally, the angle of view decreases as you increase the focal length and magnify the image.

BETWEEN-THE-LENS SHUTTER - A shutter situated between two ~.
BITMAP - A bitmap is a picture that is an arrangement of tiny squares of different colors, called pixels. For the file extension, ".bmp," see .BMP below.

Flare
An overall decrease in contrast caused by light being reflected off, instead of transmitted through, a lens surface; controllable through the use of multilayer coating of individual ~ in a lens; aggravated by unclean lens surfaces on front and rear ~ or filters.

So, being in focus simply means moving the ~ forward or backward until all the rays coming toward the camera from the subject meet at one point; the focal point on the film.

Other lenses have the ability to shift lens elements around to produce a continuous range of focal lengths. These are called zoom lenses.

Does anyone have any experience cleaning the inside of the ~?

With the sensor -- not the ~ -- moving to overcome camera shake, any lens you mount on the Alpha becomes image-stabilized glass. Considering all of the old and new lenses that will fit this camera, how's that for a bargain?

Canon are keen to point out that the S60 has a lens which utilizes 'UA lens technology'. This has ~ which have 'ultra high refraction index glass' which allows the entire lens system to be thinner (yet maintaining the same image quality).

Be wary of leaving your system in direct sunlight as the internal pressure in cameras and housings can rise rapidly. This could cause condensation on ~ or ports when you enter the cooler water, or worse a flood from a popped "0" ring seal.

[Note that since most camera lenses are made up of more than one ~, the definition "middle of the lens' is adjusted slightly.] ...

Flare and ghostings are a major problem in contra-light situations. The problem is caused by reflected light - either from the ~ or the inside of the lens barrel. There are certain techniques to reduce these reflections: ...

There are several other terms to take into consideration when buying a digital camera lens to make sure you are making the best purchase. If your lens utilizes aspheric ~, ...

By positioning your subject in such a way, you're inviting that stray light to do its reflecty thing on those internal ~. Depending on how you meter the scene, this may actually turn your subject into a silhouette, which might also be pretty cool.

There is some sort of mechanism in the camera that moves the ~ to bring the image into focus. Some cameras are quite good at this and some have difficulty in low light situations.

Focus. A lens function that brings a scene or image into sharpness through the movement of optical ~ inside the barrel of a lens.

Lens barrel - metal or plastic tube with a blackened inner surface, in which the ~ and mechanical components of the lens are mounted.
Lens cap - plastic, rubber or metal cover which fits over the front or back of the lens to protect it.

Glare occurs when there is direct light going into the lens. This often makes the image look soft due to the light reflecting inside and between the ~. Lenses with good coatings have less of an issue with glare.

This act of focusing moves the elements inside the lens, and as the subject distance decreases, the (actual) focal point moves further away from the lens (in reality, the camera's sensor is stationary, and the ~ move away from it as the lens is focused).

Air Lens: A lens using an “air gap' (which has a refractive index of 1.0) between a pair of ~.

Fig. 1: For the sake of simplicity, this diagram shows only one lens element. In actuality, an interchangeable VR lens has many ~.

Zoom lenses are more expensive, a little bulkier, and the optical quality of some zoom lenses might not be as sharp
as a prime lens. The reason for a slight difference in sharpness is because of the additional ~ and
moving parts required to manufacture a zoom lens.

Image stabilization. A technology that compensates for camera shake, usually by adjusting the position of the camera sensor or ~ in response to movements of the camera.

A major flaw with the G series: the need for lens barrel replacements every 6-12 months due to debris infiltration between the ~.

Extension tubes are hollow tubes of varying lengths that increase the focal distance of the lens by moving the ~ further from the film or sensor. Extension tubes on current cameras generally disables the autofocus feature.

With two extra-low dispersion glass elements and three aspherical lens elements, the lens delivers high-resolution, high-contrast images while minimising chromatic aberration. Ideally suited for use on Nikon DX-format and FX-format cameras. Approx £550 ...

(Your condensed breath on the lens also works well.) Never put cleaning fluid directly on the lens; it might run between the ~. Using a circular motion, clean the lens surface with the cloth or tissue, then use the cloth or a tissue rolled and torn the same way to dry.

planes than the camera's sensor, resulting in red-ish or blue-ish glow around contrasting edges. Vignetting is darkening of the corners, usually occurring in cheap lenses and wide open apertures. Flare is caused usually by direct sunlight and due to reflecting of light between ~, ...

Good optics can overcome this problem, and the iPhone 4S has 5 ~ to help keep things as sharp as possible. Good optical glass can be extremely expensive, and I'm still surprised by the quality of the 4S's camera. In the photography world, lenses with low f/stops can get very pricey.

See also: See also: What is the meaning of Lens element, Element, Lens, Camera, Light?

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