Glossary


  • AF: Nikon's first auto-focus design.  This design utilizes a motor in the camera body and the focus ring is driven through a mechanical coupling that appears like a tiny flat blade screwdriver on the camera side, and a tiny flat blade screw on the lens side.  These lenses only say AF on them and have a thin hard focus ring that makes them inconvenient for manual focus operation.  These also have a small button to lock the aperture ring at the smallest aperture that is too easy to press causing the aperture to not be at the smallest aperture giving you the FEE error on most modern DSLRs.  Will auto-focus on older AF film cameras and on mid and pro tier cameras.  These lenses will not auto-focus on the lower tier DSLRs like the D3x00 series, D5x00 series, and D40.  On these cameras it will function as an Ai-P lens.
  • AF-n: A evolution of AF this design still only retains the AF marking on the lens but has a wider and much easier to use focus ring making them much easier to use for manual focus, but retains the small too easy to press aperture button.
  • AF-D: An evolution of the AF-n design.  This design is marked AF-D and provides distance information back to the camera.  This helps the camera determine proper flash exposure.  Another feature of these lenses is that the small button has been replaced by a far more ergonomic switch.
  • AF-I: Internal motor auto-focus that is controlled electronically rather than by a mechanical link from the camera.  There are very few AF-I lenses, and all of these were high end professional models.  AF-I works on all Nikon DSLR cameras.
  • AF-S: Internal "Silent Wave" motor that is controlled electronically rather than by a mechanical link from the camera.  This is the current standard of Nikon auto-focus and nearly every current lens design is available in AF-S.  AF-S works on all Nikon DSLR cameras.
  • Ai: Manual focus lens with auto indexed aperture coupling.  Lenses prior to Ai had a fork on the aperture ring to couple the light meter to the aperture ring, Ai replaced coupling fork with a cutout on the aperture ring that is used by a mechanical coupling feeler that allows the camera to detect the aperture setting.
  • Ai-P: Manual focus lens that is an advancement of Ai-S has the electronic support circuitry for AF cameras.  This will allow metering and all PSAM modes on all Nikon DSLRs.  There are very few factory Nikon Ai-P lenses, but there are aftermarket Ai-P lenses from Zeiss, Voigtlaender, and others.
  • Ai-S:  Manual focus lens that is a small advancement of Ai which changes the relation of movement of the mechanical stop down arm.  In prior lenses the stop down arm simply closed down the aperture to the desired setting, but to support Program mode and all the camera to select the proper aperture the movement of the stop down arm was modified to have a linear movement with the aperture so that each stop of the aperture requires the same movement of the stop down arm.
  • Aperture: A variable sized hole inside of a lens.  The theoretical size of the hole is f/a where f = focal length of the lens and a is the aperture ratio.  The the diameter of an aperture set to f/2 on a 50mm lens would be 50mm/2 or 25mm.  The aperture numbers are logarithmic hence the numbering sequence of 1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32...
  • D3x00 Series: Nikon D3000, D3100, and D3200.
  • D5x00 Series: Nikon D5000, D5100, and D5200.
  • Exposure Value (EV): EV is a measure of available light.  Every step in EV is one stop, and as EV value gets larger, then the scene is brighter.  For example, EV15 is a sunny afternoon.  EV0 is ISO100, f/1, and 1sec.  EV1 is one stop brighter so you have to adjust your exposure 1 stop, i.e. ISO100, f/1.4, and 1sec.  So for a sunny afternoon we need to compensate for another 14 stops, i.e. ISO100, f/8, and 1/500sec.
  • FEE: Common error message shown in the aperture area of the viewfinder or display.  This error indicates that the aperture is not set to it's minimum aperture setting.  Set the aperture to the minimum aperture and it should go away.
  • PSAM: Acronym referring to the Program, Shutter preferred, Aperture preferred, and Manual modes of modern SLR cameras.  Canon calls Shutter preferred "Tv" and Aperture preferred "Av".
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