Another DO patent
We haven’t seen a new DO lens in a long time, but the patents haven’t stopped. It looks like Canon is continuing the R&D, I’d love to see it go somewhere.
Interpretation and self-description of the patent literature
- Patent Publication No. 2013-64858
- 2013.4.11 Release Date
- Filing date 2011.9.16
- Focal length f = 392.12mm
- Fno. 4.12
- Half angle of ω = 3.16 °
- Image height Y = 21.64mm
- 262.14mm length lens
- BF 69.97mm
- Two fluorite
- Materials and anomalous partial dispersion DOE to use, reduce the chromatic aberration
- Refractive power of the diffractive surface
- Strong, but can reduce the chromatic aberration of the element itself, flare increases
- The weaker, other optical element DOE play a role
- Refractive optical unit
- DOE anomalous partial dispersion and bonding materials
- DOE aspherical surface on the opposite side of the
- Vibration control
- Inner Focus
Source: [EG] | Canon EF 400 f/4 DO IS
More diffractive optic patents from Canon. This time, another 600 f/4 IS DO lens and a 400 f/2.8 DO IS.
With the cost of the new super telephotos from Canon, I can’t imagine what new DO lenses would cost.
Continue reading for the patent breakdown….
More DO Lenses?
A few patents in regards to diffractive optics have come about. 70-300 f/4.5-5.6 DO IS, 14 f/2.8 DO and a 600 f/4 DO IS.
Diffractive optic patents keep coming up, though no new products are being announced. It does appear Canon is invested in the technology and thinks there is a market for it. I am a big fan of the 400 DO and hope to see longer DO lenses in the future.
Read more about the patents after the break.
More lens patents
This is an interesting DO patent from Canon. There seems to be a lot of them showing up, but no new DO products in a long while.
I’ve been told the lack of an A+ filterable wide angle from Canon for a full frame camera will be addressed sooner than later. Yes, there’s Zeiss, but most want AF.
Patent Publication No. 2011-145518
- Release Date 2011.7.28
- Filing date 2010.1.15
- Focal length f = 16.48 – 24.00 – 33.95 mm
- Fno = 2.91
- Half angle of 52.70 – 42.04 – 32.51 °
- 4 aspherical surfaces
- Zoom Ratio 2.06
- Four-group zoom lens plus a negative sign
- Second lens focusing is performed by Inner Focus
- Solve various problems using the diffractive optical element
- The astigmatism of the telephoto kept in order, to increase the refractive index of the positive lens
- A high refractive index, chromatic aberration occurs
- Aberration and astigmatism in the center of the telephoto image has a correlation, it is difficult to simultaneously correct
- Made achromatic diffractive optical element, a positive lens astigmatism correcting high refractive index