<H1>Canon Super Telephotos With Macro Patents</H1>

Our friends at Egami, the Japanese Photography blog has discovered four new Canon patents, all with Diffractive Optics and Macros - EF 400mm f/4 DO Macro 1:1.4 ; EF 400mm f/4 DO Macro 2:1 ; EF 600mm f/4 DO Macro 1:1 ; EF 800mm f/4 DO Macro 1:1

It is important to point out a big optical and photographic company like Canon files tens of thousands of patents every year and they spend lots of money into research and development. However, most R&D do not result in a product that finally comes to market but it is interesting to see what some Canon researchers are up to.

You can visit my website MichaelDanielHo.com to see what I am up to and what photo shoots I have planned for 2013.

Canon EF 400mm f/4 DO Macro 1:1.4

Canon EF 600mm f/4 DO Macro 1:1

Canon EF 800mm f/5.6 DO Macro 1:1

Canon EF 400mm f/4 Macro 2:1

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 aberrations occur 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