 Michael |
What Is APO Hi! Can anyone explain what APO is in relation to lenses? Thanks!
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Pete H |
Michael, APO is simply shorthand for "Apochromatic." Uncorrected lenses exhibit Chromatic and Spherical abberations - which is the inability to focus ALL colors to a specified distance behind the objective lens. APO is not the only way to correct for this, though it is certainly the preferred and generally more expensive design. Hope that helps!
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Jon Close |
APO is a term also commonly applied to telescopes. While the same types of corrections are made to camera lenses, not all makers use the term. Leica, Zeiss, Sigma and Minolta use the term "APO" in naming their lenses. Canon, Nikon, Tamron, and others also make lenses well-corrected for chromatic aberrations and technically apochromatic, but do not use the term "APO". Instead, they tout the special lens elements used to achieve this, especially fluorite crystal and low-dispersion glass. Even there the different companies use different terms for essentially the same thing. UD (ultralow dispersion) and SUD (super low dispersion) in Canon, ED (extra low dispersion) in Nikon, LD (low dispersion) and AD (anomalous dispersion) in Tamron, SD (super low dispersion) and HLD (high refractive low dispersion) in Tokina, SLD (special low dispersion) and ELD (extraordinary low dispersion) in Sigma, etc.
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Michael |
yeah thanx that helps. I was wondering because there are so many different abbr. out there and since I am kinda new to this, I wasn't sure what they all meant. :D BTW, I hadn't thought to look online. thanx Pete. PS thanx for all that info Jon. it certainly helps. :D Michael
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