Canon patent for 400mm f/2.8L IS lens with built-in extender

canon patent

Canon’s labs are working without interruption. Here we have a Canon patent for a 400mm f/2.8L IS lens with built-in extender.

  • Patent publication number 2016-191761
    • Release date 2016.11.10
    • Application date 2015.3.31
  • Main lens
    • Focal distance 392.57
    • F number 2.90
    • Field of View 3.15
    • Image height 21.64
    • Lens total length 371.15
    • BF 44.00
  • Example 1
    • First state magnification 1.40
    • Second state magnification 1.70

Excerpt from the patent literature:

[Claim(s)] [Claim 1] In a rear converter lens expandable to a long focal length by equipping the image surface side of a main lens,
Magnification can be changed by switching some or all of the rear converter lens,
Magnification of the n-th state of a rear converter lens from an installing surface which guarantees mechanically a relative position on an optic axis of beta_n, a rear converter lens, and a main lens, When average value of Sk_n and Sk_n of each state is made into Sk_ave for distance to a paraxial image surface position of the n-th state when a main lens is equipped with a rear converter lens
| (Sk_n-Sk_ave) x beta_n | < 0.10
A satisfied rear converter lens.
[Claim 2] When a focal distance of a rear converter lens of f_max and a minimum magnification state is made into f_min for a focal distance of a rear converter lens of a maximum magnification state of the aforementioned rear converter lens
1.5 < |f_min/f_max| < 10.0
The satisfied rear converter lens according to claim 1.
[Claim 3] When a forward side principal point position of ho_max and a minimum magnification state is made into ho_min for a forward side principal point position of a maximum magnification state of the aforementioned rear converter lens
0.05 (ho_max -ho_min) < /root(f_max^2+f_min^2) < 0.28
The satisfied rear converter lens according to claim 1.
[Claim 4] The rear converter lens according to claim 1 in which the aforementioned rear converter lens is characterized by some or all of a rear converter lens changing to optical axis direction and vertical direction at the time of magnification change.
[Claim 5] The rear converter lens according to claim 1, wherein the aforementioned rear converter lens has the 1st lens group Lfix of fixing at the time of magnification change in order, and the 2nd switchable lens group Lex from the object side.
[Claim 6] When a focal distance of a change group of fex_max and a minimum magnification state is made into fex_min for a focal distance of a change group of a maximum magnification state of the aforementioned rear converter lens
1.1 < |fex_min/fex_max| < 5.0
The satisfied rear converter lens according to claim 5.
[Claim 7] A focal distance of the n-th lens of a change group of a maximum magnification state of the aforementioned rear converter lens, a refractive index of d line, and magnification, respectively f_max_n, When a focal distance of the n-th lens of a change group of nd_max_n, betamax, and a minimum magnification state, a refractive index of d line, and magnification are set to f_min_n, nd_min_n, and betamin, respectively
-(sigma(1/(nd_min_nxf_min_n))/ sigma(1/(nd_max_nxf_max_n))-1) 0.7 < *(beta min/beta max) < 0.7
The satisfied rear converter lens according to claim 5.
[Claim 8] A focal distance of the n-th lens of a change group of a maximum magnification state of the aforementioned rear converter lens, an Abbe number of d line, and magnification, respectively f_max_n, When a focal distance of the n-th lens of a change group of vd_max_n, betamax, and a minimum magnification state, an Abbe number of d line, and magnification are set to f_min_n, vd_min_n, and betamin, respectively
-(sigma(1/(vd_min_nxf_min_n))/ sigma(1/(vd_max_nxf_max_n))-1) 0.7 < * (beta min/beta max) < 0.7
The satisfied rear converter lens according to claim 5.
[Claim 9] From an installing surface guaranteed mechanically, a relative position on an optic axis of the aforementioned rear converter lens and a main lens, Most average value of Dex_n of each state when distance to a point on an optic axis of a surface on the object side is made into Dex_n of the n-th status-switching group of the aforementioned rear converter lens Dex_ave, When average value of Sk_n of each state when distance from an installing surface which guarantees mechanically a relative position on an optic axis of the aforementioned rear converter lens and a main lens to a paraxial image surface position of the n-th state when a main lens is equipped with a rear converter lens is made into Sk_n is made into Sk_ave
0.08 < Dex_ave/Sk_ave < 0.40
The satisfied rear converter lens according to claim 4 or 5.
[Claim 10] From an installing surface guaranteed mechanically, a relative position on an optic axis of the aforementioned rear converter lens and a main lens, Most distance of a fixing group of the aforementioned rear converter lens which it is to a point on an optic axis of a surface on the object side Dfix, When average value of Sk_n of each state when distance from an installing surface which guarantees mechanically a relative position on an optic axis of the aforementioned rear converter lens and a main lens to a paraxial image surface position of the n-th state when a main lens is equipped with a rear converter lens is made into Sk_n is made into Sk_ave
-0.20 < Dfix/Sk_ave < 0.00
The satisfied rear converter lens according to claim 4 or 5.
[Claim 11] The rear converter lens according to claim 5, wherein the aforementioned rear converter lens has an aspheric surface in the 1st lens group of fixing to the time of magnification change.

canon patent

[via Egami]

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Sigma patent for 400mm f/2.8 OS Sport Lens

400

Egami (translated) spotted an interesting patent filed by Sigma. It refers to a 400mm f/2.8, image-stabilized lens. This lens will be part of Sigma’s “Sport” line-up.

  • Patent Publication No. 2015-64436
    • Published 2015.4.9
    • Filing date 2013.9.4
  • Example 1
    • Focal length 390.00mm
    • Fno. 2.91
    • Total angle of view 2ω 6.29 °
    • Image height Y 21.63mm
    • Overall length of the lens 353.00mm
    • Positive, positive positive and negative negative 5-group configuration
    • Inner Focus (fourth group)
    • Anti-vibration (part of the fifth group)

Canon 400mm f/4 DO IS II Review (Imaging Resource)

Canon EF 400mm f/4L IS DO II

SLRGear posted their review of Canon’s new 400mm f/4 DO IS II lens, announced last September for Photokina.

Some excerpts from the review:

  • On a full-frame body, the Canon 400mm DO II is sharp, though not as tack sharp as the 400mm ƒ/2.8 II
  • As one would hope from a nearly-$7000 lens, chromatic aberration is very minimal. On both full- and sub-frame cameras, CA was very low
  • […] vignetting on this telephoto lens is very, very low.
  • […] geometric distortion on the Canon 400mm DO II is practically nonexistent
  • […] this large lens is, as they say, “built like a tank”. The build quality is simply impressive […]

From the conclusion:

The Canon EF 400mm ƒ/4 DO IS II USM is a fantastic, professional-level supertelephoto lens. As a significant upgrade optically compared to the original version, the 400mm DO II is an even more attractive option over the heavy, expensive 400mm ƒ/2.8L IS II. For professional and serious wildlife, sports and action photographers who don’t want or need a fast, low-light-friendly ƒ/2.8 supertelephoto prime, the 400mm DO II version offers healthy savings in both cost and weight. Image quality is very good, and the built-in I.S is extremely impressive

The review comes with charts and sample pics.

The Canon 400mm f/4 DO IS II lens is not a budget lens. It sells for around $7000 (B&H Photo | Adorama).

Specs:

  • EF Mount Lens/Full-Frame Format
  • Gapless Dual-Layer Diffractive Optics
  • Large Diameter Aspherical Element
  • Ultra Low Dispersion Element
  • Protective Fluorine Coatings
  • Ultrasonic AF Motor and Internal Focus
  • Optical Image Stabilizer with 3 Modes
  • Power Focus Mode; Full-Time MF Override
  • Dust- and Water-Resistant Construction
  • Rounded 9-Blade Diaphragm
[via SLRGear ]

Canon 400mm f/4 DO IS II Amazon | B&H Photo | Digitalrev | eBay | Adorama | Canon USA

IMG_424278

Canon Ambassador Richard Walch about EOS 7D Mark II And EF 400mm f/4 DO IS II

FotoTV on Youtube published an interview with Canon Ambassador Richard Walch about the new EOS 7D Mark II and the likewise new EF 400mm f/4 DO IS II lens.

The EOS 7D Mark II is available for pre-order. In Germany Wex Photographie is accepting pre-orders for the EOS 7D Mark II (€1,699). The new EOS 7D Mark II can be pre-ordered also in the USA. Shipment is expected for November 2014 and orders will be shipped on a first come first serve basis:

7d2_king

World-wide pre-order links after the break.

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