Four New Canon Telephoto Lens Patents: 2 x 400mm f/4, 600mm f/4 and 800mm f/5.6, all with macro)

Once more Egami (translated) spotted interesting new patents filed by Canon. A 400mm f/4 DO macro 1:1.4, a 400mm f/4 DO macro 2:1, a 600mm f/4 macro 1:1 and an 800mm f/5.6 DO macro 1:1. All lenses feature diffractive optical elements (the DO in the naming)

Self-interpretation and summary, Patent Documents

• Patent Publication No. 2012-242742
  • Release Date 2012.12.10
  • Filing date 2011.5.23
• Example 1
  • Focal length f = 788.34mm
  • Fno. = 5.80
  • 2ω = 3.14 ° angle of view
  • Image height 21.64mm
  • 486.00mm length lens
  • BF 110.67mm
  • β = -1.02
  • (The second and third group is for the focus) consists of four groups of positive and negative polarity
  • (One side of the image, such as the most protective glass) x 17 lens elements in 12 groups composed
  • Maximum effective diameter 135.92mm
  • Two two-sided aspherical
  • DOE 1 surface
  • One fluorite
  • Three Super UD glass
  • One low-dispersion glass
• Example 2
  • Focal length f = 400.00mm
  • Fno. = 4.12
  • 2ω = 6.20 ° angle of view
  • Image height 21.64mm
  • 300.00mm length lens
  • BF 55.00mm
  • β = -2
  • (For the second focus group 2,4) consists of four groups of positive and negative positive negative
  • (One side of the image, such as the most protective glass) x 19 lens elements in 12 groups composed
  • Maximum effective diameter 97.09mm
  • Five 5-sided aspherical
  • DOE 1 surface
  • Two fluorite
  • 1 UD glass sheet
  • One low-dispersion glass
• Example 6
  • Focal length f = 585.00mm
  • Fno. = 4.12
  • 2ω = 4.24 ° angle of view
  • Image height 21.64mm
  • 350.00mm length lens
  • BF 55.00mm
  • β = -1
  • (For the second focus group 2,4,5) group configuration 6 positive negative positive positive negative
  • (One side of the image, such as the most protective glass) 22 sheets 13 groups lens configuration
  • Maximum effective diameter 142.00mm
  • Four four-sided aspherical
  • DOE 1 surface
  • Two fluorite
  • 1 UD glass sheet
• Example 9
  • Focal length f = 390.99mm
  • Fno. = 4.12
  • 2ω = 6.34 ° angle of view
  • Image height 21.64mm
  • 256.40mm length lens
  • BF 62.35mm
  • β = -0.7
  • (For the second focus group 2,4) consists of four groups of positive and negative positive negative
  • (One side of the image, such as the most protective glass) x 16 elements in 12 groups lens configuration
  • Maximum effective diameter 94.90mm
  • Four four-sided aspherical
  • DOE 1 surface
  • 2 UD glass sheets
  • Two low-dispersion glass
• Inner focusing formula
  • Easy to shorten the minimum focusing distance
  • AF is faster
  • Large variations in aberrations
  • Many aberration occurs at close range
• Inner focusing high-performance formula
  • With a focus group of two or more
  • However, optimization of the parameter is mandatory
  • In the macro range of 0.5 times more difficult to correct aberrations
• Diffractive optics
  • Shortening of the total length can be
  • Distance of the lens group becomes narrow, the range of movement of the focus group will be limited
• Canon patent
• Group before and after the group of positive and negative
• Inner Focus (and the second group, one of the rear group)
• By setting multiple focus groups, perform the division of sensitivity, the amount of movement
• In short travel distance, is focused on the short-range

[via Egami]