Canon Patent two new DO Lenses – 70-300mm, 100-400 mm F4.5-5.6 DO Lens, image and details below
Description and self-interpretation of the patent literature
- Patent Publication No. 2014-89385
- Publication date 2014.5.15
- Filing date 2012.10.31
- Example 1
- Zoom ratio 3.78
- Focal length f = 103.00-200.00-388.94mm
- Fno. 4.63-5.24-5.83
- Half angle ω = 11.86-6.17-3.18 °
- Image height Y = 21.64mm
- 228.82-273.58-303.10mm total length
- BF 69.48-90.93-105.73mm
- Example 6
- Zoom ratio 4.00
- Focal length f = 72.50-135.00-289.99mm
- Fno. 4.44-5.04-5.85
- Half angle ω = 16.62-9.10-4.27 °
- Image height Y = 21.64mm
- 143.91-177.69-203.15mm total length
- BF 39.10-39.10-39.10mm
Canon diffractive optical (DO) Lenses are smaller and lighter compared to the lenses of same focal length, for example EF 70–300mm f/4.5–5.6 DO IS USM lens is 28 percent shorter than the EF 70–300mm f/4–5.6 IS USM lens. But the price DO lenses are generally high compared to the normal lenses of same focal length.
