FAQ sorted by alfabet
In this section the most common technical terms will be described. Select the first letter of the abbreviation or term you'd like to search for:A - B - C - D - E - F - G - H - I - J - K - L - M - N - O - P - Q - R - S - T - U - V - W - X - Y - Z
UD
The so called APO elements (like the UD, SUD, CaF2, LD, SLD and ED for example) improve sharpness and contrast by reducing the effects of chromatic aberrations that are typically found in telelenses. These elements work by focussing different wavelengths of light to one point, but the effectiveness depends highly on the quality of the glass that is used. The good elements are highly expensive; the good ones are to be found in the more expensive lenses.
USM
SWM lenses (USM, AF-S, HSM, SSM) use a Silent Wave Motor (SWM) to focus the lens. It results in extremely fast operation while it’s very quiet when compared to the micro motor lenses. The focus is also very accurate even in low light.