Alley in Pisa, Italy

by Lars Kotthoff

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visits member for 1 year, 7 months
seen Jan 18 '13 at 7:21

Apr
24
awarded  Popular Question
May
29
awarded  Nice Question
Jan
1
comment Why don't most cameras use infrared for focusing?
My D5000 has the most brightest, obtrusive light. However, APO lenses (a majority of lenses, right?) are corrected for near-IR. Is focusing still a problem?
Jan
1
comment Why don't most cameras use infrared for focusing?
From Wikipedia: "Most apochromatic ('APO') lenses do not have an Infrared index mark and do not need to be refocused for the infrared spectrum because they are already optically corrected into the near-infrared spectrum." I believe Nikon "ED" designation lenses are also apochromatic. Doesn't that mean that the image would be in focus?
Dec
31
awarded  Student
Dec
31
comment Why don't most cameras use infrared for focusing?
Thanks for the comment. The red light you see from speedlights isnt infrared, its just red light. Was that what you were referring to?
Dec
31
asked Why don't most cameras use infrared for focusing?