Optimal Lens Range ?

Discussion in 'Leica and Rangefinders' started by david_clark|4, Jun 3, 2006.

  1. When they are describing lens performance, and they say that the lens performs
    best at medium range and mid-apertures - what I want to know is just what is
    the distance of the medium range? Is it halfway between 50 ft. and a yard on a
    50mm lens scale, or is it half way between you and horizon? And what is
    considered the near and far distance of their mid range? Thanks.
     
  2. "Medium range" is usually around 30x the focal length. Normally there's not much difference between that and performance at infinity.

    Lenses which focus by simple linear extension usually perform less well when the focus distance drops below maybe 10x their focal length.
     
  3. Really ? In that case a lens with a focal length of 50mm (2 inches) will be best at (2X30) 60", and a 300 mm lens at 30 ft. And the wide angles- a 28mm best at about 2 1/2 ft. ?- all these distances seem awfully short...
     
  4. Bob, how did you determine that the "medium range" is "30x the focal length"? Where did you see this?
     
  5. Hey, don't question the guy, he's an expert with a website and everything :*)
     
  6. All you doubters above need to realize that at any other distance (closer or further away) lenses will give you around 95+% of their best performance, unless you go to true macro with a curved field lens.

    So, it is not the lens, since it is quite near optimal on most of its range, but our own faulty technique. Food for thought, in my book. ...
     
  7. How ever far away the subject is.
     
  8. I could not understand the first two sentences of your post, Frank. Would you clarify? TIA.
     
  9. Mid-range wouldd be the part that's neither very close, nor really far away. :) The fat part of the distance scale that isn't up against the stops. Mid-aperture for most 35mm format lenses is somewhere around f/5.6 to f/11, where the lens is stopped down enough to hit maximum resolution and the effects of diffraction haven't set in.

    People who realise they shoot most of their photos at mid-range and mid-aperture can save themselves a lot of money by not buying 'luxes.
     
  10. As I understand it, most Leica M lenses are optimized for long distances relative to their focal lengths (except the 90/4 Macro-Elmar-M). The close-up performance (less than 3 meters and especially less than 1 meter) will not be as good as that at longer distances, and it is better to stop the lens down if possible, for close distances if maximal sharpness is required. Even the MEM will perform better at medium-long distances than at short distances.

    Also bear in mind that it is harder to correct wide aperture lenses (F/1.4) for excellent close-up performance than F/2 or F/2.8 lenses.
     
  11. It would seem then that the best way to focus for optimal resolution and contrast would be to dial the lens to a hyperfocual distance, say put the infinity mark on f5.6 or f8 on the scale for a mid range, and use the camera like that.
     

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