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    Patent: Dual internal teleconverter telephoto lens.

    By Updated:26 Comments1 Min Read Canon Patents
    patentdualtc 728x462 - Patent: Dual internal teleconverter telephoto lens.

    Is this the next evolution of the Canon EF 200-400mm f/4L IS USM 1.4x? Here is a patent showing a dual teleconverter Canon telephoto prime, an EF 400mm f/5.6.

    What's cool about the dual teleconverters, is one is a focal length reducer, so you get the EF 400mm f/5.6 and the built-in focal length reducer converter brings the lens to an EF 300mm f/4, or at the other end, a 560mm f/8 lens.

    There has long been a desire for a replacement to the classic Canon EF 400mm f/5.6L, even if Canon just added image stabilization, but this is definitely a unique direction to take the lens on Canon's part.

    Japan Patent Application 2019-70689 summary:

    Canon EF 400mm f/5.6

    • Focal length: 391.89mm
    • F number: 5.80
    • Angle of view: 3.16°
    • Image height: 21.64mm
    • Total lens length: 299.31mm
    • BF: 167.00mm

    With teleconvertor (B)

    • Focal length: 560.02mm
    • F number: 8.29
    • Angle of view: 2.21°
    • Image height: 21.64mm
    • Lens total length: 299.31mm
    • BF: 46.56mm

    With Teleconvertor (C)

    • Focal length: 286.00mm
    • F-number: 4.23
    • Angle of view: 4.33°
    • Image height: 21.64mm
    • Total lens length: 299.30mm
    • BF: 110.04mm
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    26 comments

    1. Would be a funny being! But after taking some time to look at it: A very interesting idea if you look how well the converters work with different lenses - two integrated (in terms of optical design) integrated adapters might be a three-focal-length lens with the excellent IQ of the best primes ... in one package.
    6. I would have “settled” for a 400/2.8 with 1.4x builtin, as a replacement for my 400 mk II. The 200-400 is too slow for some of the events I cover.

      If a reducer could be added, enabling 280(?) f/2, that would be absolutely mind-blowing!

      $20k or thereabouts, but worth every penny...
    7. This multi-converter lens is cool and all, but I'd much rather see something like a sub-$10k 600mm f/5.6 for us enthusiast mortals who live down here on Earth, and don't want a zoom sigma 150-600 f/6.3
    8. This multi-converter lens is cool and all, but I'd much rather see something like a sub-$10k 600mm f/5.6 for us enthusiast mortals who live down here on Earth, and don't want a zoom sigma 150-600 f/6.3
      A sub $4k 500mm f/5.6 would be my preferred choice for two reasons. First, weight and secondly wider field of view, and 500mm would help keep the price down.
    9. Not sure I get the point of this lens. Same focal length and aperture as the 100-400 which takes a 1.4 converter very nicely. I suppose a fixed focal length and matched teleconverter might be marginally sharper, but not sure it would be visibly sharper in real world use. Such a lens might be lighter than the zoom, but it would also be longer. Too long to fit in my camera bag. It would make more sense if this were an R lens. Shorter, lighter, maybe faster focus and something different to excite people.
    14. Kinda like these that we had in the days of 16x9/4x3 switchable TV cameras. Most of our ENG lenses had a built-in 2x extender, but for a while they added the option of adding in a .7x(I believe) element to maintain the FoV when the camera was switched from 16x9 to 4X3(the sides of the chips were just electronically cropped).

    15. You remember how old TV cameras (1950s?) had three lenses on a rotating mount? Given the RF's short film-to-flange you could probably make something like that that could mount 3 EF lenses.

      Leica's rangefinders also had a "Tri-Elmar" lens with three fixed focal lengths. I've used M for decades but literally have never touched the Tri-Elmars. I don't know if they're actually zooms that just have three zoom settings, or whether the image isn't really usabable between the specific focal lengths.

      https://www.newsshooter.com/2019/04/10/multi-turret-old-school-meets-new-school/
    17. Canon rocks with lenses!!! imagine if Canon makes lenses for Sony and Nikon we will have best of all worlds. Best Sensor Tech (Sony), Best weather sealing and ergonomics (Nikon&Canon), Fantastic Lenses (Canon)
    18. Ok, just give me 50mm that becomes 70mm and 35mm.

      A question to those who understand lens design - would the lens reducer work the same with a 50mm lens?

      My limited understanding is it's easy to add a focal length reducer in this case because 400mm / 5.6 is larger than a full frame sensor's diagonal, similar to what's done with speed boosters from FF lenses to crop bodies. My understanding is repeating the trick with a 50mm would require it to have a much larger power of coverage, similar to the TS-E 45mm (though without the mechanics to tilt and shift it, which isn't trivial).
    19. I would have “settled” for a 400/2.8 with 1.4x builtin, as a replacement for my 400 mk II. The 200-400 is too slow for some of the events I cover.

      If a reducer could be added, enabling 280(?) f/2, that would be absolutely mind-blowing!

      $20k or thereabouts, but worth every penny...
      why so expensive ?
      The basic 400F5.6 is £1200, adding a couple of inbuilt converters at £450 each would take it to the same price region as the 100-400 Mk 2. This would make a decent birders lens.

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