New 100-400 f/4-5.6L IS in the pipeline?
A pending patent has shown up showing a new 100-400 optical design. This new design seems to suggest better optical performance as well as starting at f/4.

Patent Publication No. 2011-180218

• 2011.9.15 Release Date
• Filing date 2010.2.26

Example 1

• Focal length f = 72.20 – 135.00 – 290.00mm
• Fno = 4.20 – 4.67 – 5.86
• Half angle of 16.68 – 9.10 – 4.27 °
• Image height 21.64mm
• Lens length 185.20 – 214.53 – 239.20mm
• Back Focus 46.74 – 47.82 – 57.41mm
• 4.02x zoom ratio
• Group 6 for each group
• Positive and negative polarity positive or negative group configuration

Example 2

• Focal length f = 102.20 – 200.00 – 390.01mm
• Fno = 4.10 – 4.55 – 5.90
• Half angle of 11.95 – 6.17 – 3.18 °
• Image height 21.64mm
• Lens length 228.18 – 258.83 – 288.12mm
• Back Focus 51.23 – 54.42 – 69.84mm
• 3.82x zoom ratio
• Group 6 for each group
• Positive and negative polarity positive or negative group configuration

Example 3

• Focal length f = 100.20 – 135.10 – 290.19mm
• Fno = 4.36 – 4.47 – 5.81
• Half angle of 12.18 – 9.10 – 4.26 °
• Image height 21.64mm
• Lens length 184.66 – 198.82 – 244.82mm
• Back Focus 42.53 – 46.68 – 63.07mm
• 2.90x zoom ratio
• 5 groups, each group
• Positive and negative group of negative polarity configuration
• High zoom ratio can be easily realized
• Rear Focus
• Can be miniaturized
• Easy full-time manual
• Suppressing the fluctuation of spherical aberration
• Upon zooming, if you move from behind the eyes, counting the two groups, the greater the variation of spherical aberration in the focusing
• On-axis beam angle θ the following equation:
• θ = AISN (1 / 2 * Fno)
• Spherical aberration is proportional to the fourth power of the high on-axis ray
• In focusing heavily on the object side to move first, counting from one group behind, which varies significantly higher on-axis ray
• Canon's patents, and by fixing the first two groups, counting from the back of the eye movement to limit the amount counted from the first team back, suppressing the fluctuation of spherical aberration
via [EG]
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