Is a true pancake lens impossible?

Discussion in 'Native Lenses' started by Basset, Dec 28, 2011.

  1. Basset

    Basset Mu-43 Regular

    Nov 9, 2011
    I have read the many rave reviews of the Olympus 45 / 1.8. Is there a genuine physical limitation on making a smaller lens for that focal length? Or is the limitation economic?

    I am just thinking about the Pentax DA 40 pancake lens (image here), and wonder whether such a thing is possible in the 4/3 world.
  2. spatulaboy

    spatulaboy I'm not really here Subscribing Member

    Jul 13, 2011
    North Carolina
    20mm 1.7?
  3. phigmov

    phigmov Mu-43 Hall of Famer Subscribing Member

    Apr 4, 2010
    I've got the Pen F Zuiko 38mm & 40mm lenses (f1.8 & 1.4 respectively) - with an adaptor they seem to be roughly the same length as the new 45mm Zuiko. Obviously the old lenses were steel and lacked the automatic-fucos gubbins of the new lens.

    One thing to remember is the Pentax body may be a bit deeper (so longer lens to sensor) which might make it a little easier to do shorter/thinner lenses. Nikon had a fairly thin 50mm f1.8 E pancake lens too.

    Having said that the Pen F Zuiko 38mm f2.8 is tinier still - might win the 'most pancakey lens capable of being used on a 35mm camera' award.

    I'm sure theres some fancy lens-design software out there that will let you play with various variables to produce a lens optimised for particular things (eg size, cost, weight, sharpness, bokeh etc).
  4. Aegon

    Aegon Mu-43 Veteran

    Nov 3, 2011
    Portland, OR
    Pentax makes a 70mm/2.4 that is physically more compact (when hood and cap are removed). It covers APS-C, so presumably a ยต4/3 variant on that design could have a smaller diameter.
  5. RobWatson

    RobWatson Mu-43 Hall of Famer

    Well, to a first approximation shorter focal length lenses have greater curvature on the lens elements so they tend to be physically thicker.

    As the F number goes up things get smaller. With decreasing F number more and more control of abberations becomes tricker which usually means more glass and exotic materials and shapes so again bigger-these also add to cost.

    A simple plano-convex lens of 48mm F1.8 is fairly small (for MFT image circle) but image quality not so nice.