What is aspherical IF?

Discussion in 'Adapted Lenses' started by alaios, Mar 21, 2013.

  1. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
  2. Mattithjah

    Mattithjah TalkEmount Veteran

    Jan 17, 2013
    Czech Republic

    IF -- It mean internal focusing, so front element does not rotate or move and physical lenght of lens does not change during focusing
    Ashperical -- It mean there is/are some optic element/s in the lens with aspherical shape, good for correction of chromatic aberation etc.

    Asph. optics are common in modern lenses, including cheap one (cheap plastic aspherical elements).
  3. xXx1

    xXx1 TalkEmount All-Pro

    Jan 15, 2013
    Spherical lenses don't have a single focal point but a short focal line. It is one major reason for low resolution of lenses. With one aspherical lens one can correct errors of many spherical lenses so image quality can be much higher. In the old days making such a lens was pretty expensive and calculations nightmare.

    With computer simulation software and modern lens making techniques it is easy. Therefore even small comppanies like Samyang are able to make quite good lenses.
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