GLOSSARY OF TERMINOLOGY

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ASPHERICAL ELEMENTS NORMAL GLASS ELEMENTS ARE CURVED, SO FORM A PORTION OF A SPHERE. THIS INTRODUCES DISTORTION AROUND THE IMAGE EDGES, SO MANY LENS MANUFACTURERS USE SOME ELEMENTS WITH A NONSPHERICAL DESIGN. THIS MINIMISES THE DISTORTION EFFECT AND INCREASES CORNER-TO-CORNER QUALITY. ‘ASP’ IS A COMMON INDICATOR OF ASPHERICAL ELEMENT USAGE.

INTERNAL FOCUSING PROFESSIONAL LENSES USE A MORE ADVANCED FOCUSING SYSTEM THAT MOVES THE LENS ELEMENTS WITHIN THE BARREL, SO THAT THE FRONT ELEMENT DOES NOT EXTEND OR ROTATE. THIS IS ESPECIALLY USEFUL IN WIDE-ANGLE OPTICS, SINCE LANDSCAPE PHOTOGRAPHERS USE FILTERS THAT THEY NEED TO REMAIN STATIONARY – POLARISERS AND ND GRADS IN PARTICULAR.

NANO CRYSTAL COATINGS WHILE ‘NANO CRYSTAL’ IS A NIKON TERM, THE USE OF SMALL CRYSTALLINE STRUCTURES ON LENS SURFACES IS A POPULAR TECHNIQUE AMONGST MANUFACTURERS. THESE SUBSTANCES HELP MINIMISE FLARE AND INTERNAL REFLECTIONS, WHICH CAN CAUSE GHOSTING EFFECTS. THE WIDE FIELD OF VIEW MAKES WIDE ANGLES SUSCEPTIBLE TO THIS, WHEN SHOOTING TOWARDS A STRONG LIGHT SOURCE.

SPECIAL LENS ELEMENTS MODERN LENSES OFTEN FEATURE ED (EXTRA

LOW DISPERSION) AND FLUORITE GLASS IN THEIR CONSTRUCTION. THESE ELEMENTS ARE BETTER AT KEEPING DIFFERENT WAVELENGTHS OF LIGHT TIGHTLY FOCUSED, THEREBY REDUCING CHROMATIC ABERRATION OR COLOURED FRINGING, WHICH OCCURS WHEN WAVELENGTHS DO NOT ALL CONVERGE UNIFORMLY. SUPER ED TECHNOLOGY MAY ALSO BE PRESENT IN PRO MODELS.

FLUORINE COATING SOME LENSES MAY HAVE A SPECIAL FLUORINE-BASED SUBSTANCE APPLIED TO THE FRONT ELEMENT, TO REDUCE THE ADHESION OF DUST PARTICLES AND TO REPEL WATER DROPLETS. SUCH PROPERTIES

HELP MAINTAIN IMAGE QUALITY WHEN SHOOTING IN EXTREME ENVIRONMENTS OR POOR WEATHER CONDITIONS, AND EXTEND LENS LIFE BY MINIMISING CLEANING-INDUCED SURFACE SCRATCHING.

SENSOR COMPATIBILITY NOT EVERY LENS CAN BE PAIRED WITH ALL SENSOR TYPES. FULL-FRAME LENSES MAY BE USED ON BOTH APS-C AND FULL-FRAME CAMERAS, BUT OPTICS

WITH EF-S, DX, DIII, DC ETC (ON CANON, NIKON, TAMRON AND SIGMA MODELS RESPECTIVELY) ARE FOR USE WITH SMALLER SENSORS EXCLUSIVELY, TO AVOID VIGNETTING OR EVEN SENSOR DAMAGE.

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