Patent: Canon continues to work on focal length reducers

    By 19 Comments2 Mins Read Canon Patents
    patentfocallengthreducer 728x462 - Patent: Canon continues to work on focal length reducers

    Canon continues to work on focal length reducers.

    What's a focal length reducer you ask?

    It's an adapter that reduces the focal length of a lens and at the same time increases the maximum aperture, basically the opposite of teleconverters.

    Canon has yet to release such a product, but we suspect this type of converter could benefit the EOS M system as well as an upcoming APS-C EOS R body.

    Below are a bunch of focal length reduced optical formulas from Japan patent JP-A-2019-003074

    Specification and lens arrangement of master lens 1 (18-55mm, F2.8)

    • Zoom ratio: 3.05
    • Focal length: 17.50 – 53.3 mm
    • F number: 2.80 – 2.80
    • Half angle of view: 36.65 – 13.71
    • Image height: 13.02 – 13.02mm
    • Lens length: 148.81 – 172.70mm
    • Back focus: 35.51 – 40.31mm

    Specification and lens arrangement of master lens 1 with reducer 1

    • Focal length: 11.36mm
    • F number: 1.82
    • Half angle of view: 36.67
    • Image height: 8.46mm
    • Lens length: 142.26mm
    • Back focus: 2.00mm

    Specification and lens arrangement of master lens 2 (34mm, F1.4)

    • Focal length: 34.20mm
    • F number: 1.45
    • Half angle of view: 32.32
    • Image height: 21.64mm
    • Lens length: 129.16mm
    • Back focus: 39.35mm

    Specification and lens arrangement of master lens 2 with reducer 5

    • Focal length: 23.92mm
    • F number: 1.02
    • Half angle of view: 32.33
    • Image height: 15.14mm
    • Lens length: 125.59mm
    • Back focus: 2.00mm
    Some of our articles may include affiliate links. If you purchase through these links, we may earn an affiliate commission at no extra cost to you.

    Go to discussion...

    Share.

    Related Posts

    19 comments

    1. I'm not sure how this would affect an APS-C R camera - both of these seem to change it to a back focus 2 mm behind the reducer, which would work with a EF-M. I wonder if both of these are R adapters or if one of them are a new EF to EF-M adapter and the other is an R to EF-M?

      Not that they couldn't do this with an APS-C R with a R to R focal length adapter, but I don't think these specific patents apply.
    2. I'm not sure how this would affect an APS-C R camera - both of these seem to change it to a back focus 2 mm behind the reducer, which would work with a EF-M. I wonder if both of these are R adapters or if one of them are a new EF to EF-M adapter and the other is an R to EF-M?

      Not that they couldn't do this with an APS-C R with a R to R focal length adapter, but I don't think these specific patents apply.
      R to M seems to make the most sense to me.....
    5. Exciting stuff. If my calculations are correct, reducer 1 turns an APS-C sensor Camera into an actual FF equaivalent with an effectivw crop of 1 (11.36/17.5*1.6) and reducer 5 yields an effective crop factoe of 1.2 (23.92/34.2*1.6) which is still really nice.

      Probably won't be cheap adapters, if they come to market. And they really blur the lines between APS-C and FullFrame.
    8. Exciting stuff. If my calculations are correct, reducer 1 turns an APS-C sensor Camera into an actual FF equaivalent with an effectivw crop of 1 (11.36/17.5*1.6) and reducer 5 yields an effective crop factoe of 1.2 (23.92/34.2*1.6) which is still really nice.

      Probably won't be cheap adapters, if they come to market. And they really blur the lines between APS-C and FullFrame.
      Your ratios are correct, but the larger sensor being assumed for reducer 1 is actually APS-C, not FF, and the smaller sensor being assumed is even smaller than APS-C. A linear reduction of 1.58 would change the aperture by 4/3 stop and is awfully close to the 1.60 (or more typically 1.62) crop factor for Canon APS-C sensors. As much as I would like to see such a reducer for FF lenses and Canon APS-C sensors, I have to think that a good one would be extremely difficult to design and very expensive.
    9. Your ratios are correct, but the larger sensor being assumed for reducer 1 is actually APS-C, not FF, and the smaller sensor being assumed is even smaller than APS-C. A linear reduction of 1.58 would change the aperture by 4/3 stop and is awfully close to the 1.60 (or more typically 1.62) crop factor for Canon APS-C sensors. As much as I would like to see such a reducer for FF lenses and Canon APS-C sensors, I have to think that a good one would be extremely difficult to design and very expensive.
      You are right, the first adapter is shown to be used with an APS-C lens. I didn't pay attention to that. It does not necessarily mean that it could not be used with full frame lenses on an APS-C sensor. Maybe the example actually references a use case flip314 mentioned?

      Anyway, these adapters look really strange. Why does the lens length decrease when used with the reducer? And does the reducer sit inside the camera mount to enable this 2mm back focus distance or am I missing something there.

      I would have thought that producing such adapters wouldn't be too hard for Canon, seeing that the Metabones ones seem to be quite good and Canon has great Teleconverters, which are similar in principle in my mind. Honestly I'm surprised this generates so little interest on this forum.
    11. Nice of Canon to think about us. Reducers have been around for the telescope people for nearly 50 YEARS now.

      For my 8" f/10 Maksutov Cassegrain, I have a choice of a 0.63X, 0.50X , 0.40X, 0.33x and a 0.25X.

      For my refractor, a 0.8X reducer/field flattener has been available 30 years.

      I guess Cannon could see the writing in the magazines and figured "We should do something to make it look like we know what we are doing."
    12. If we do see an RF -> EF-M adaptor there's a chance it won't work with existing EF-M mount bodies because of the new protocols in RF, which I'm assuming the EF-M mount doesn't support yet.
    13. telconverter wont actually double focal lenghts its kind of magnifying glass.
      so this turbo converter is shrinking glass .should work good cause when teleconverter makes lens errors bigger ,shrinker makes them smaller :p
      I wonder could they make converter what makes possible to use hasseblad lenses on full frame canon or even big camera lenses?
      I dont like how wide angles makes foregound big and backround smaller ,shrink glass would be lot nicer for landscapes
      Well i guess canon wont do it cause they want peoples use canon lenses ,not hasselblads :p
      hmm maybe canon could make 50mm lens with excellent 6x4cm picture field and inbuild shrinker glass . 3x panorama would be 10x6cm o_O
    14. I dont like how wide angles makes foregound big and backround smaller ,shrink glass would be lot nicer for landscapes
      That's not a property of the lens. It's perspecitive. No adapter or converter will help you with that.
    15. That's not a property of the lens. It's perspecitive. No adapter or converter will help you with that.
      Unless your lens is large enough... larger than the objects you shoot.

      For landscapes, that would mean a very huge lens. Still, a swarm of drones could probably do it.
    16. That's not a property of the lens. It's perspecitive. No adapter or converter will help you with that.
      i meaned i dont like how wide angle lens differs how eye sees world.
      thats why i want 50mm lens
    17. telconverter wont actually double focal lenghts its kind of magnifying glass.
      so this turbo converter is shrinking glass .should work good cause when teleconverter makes lens errors bigger ,shrinker makes them smaller :p
      I wonder could they make converter what makes possible to use hasseblad lenses on full frame canon or even big camera lenses?
      I dont like how wide angles makes foregound big and backround smaller ,shrink glass would be lot nicer for landscapes
      Well i guess canon wont do it cause they want peoples use canon lenses ,not hasselblads :p
      hmm maybe canon could make 50mm lens with excellent 6x4cm picture field and inbuild shrinker glass . 3x panorama would be 10x6cm o_O
      Of course, Canon won't make one for Hassleblad, but there are plenty converters that adapt to EF, then just put a converter on to that. I'm not sure if you would get the edges of the image clipped by the adapter.

      I have a adapter but no longer have Hassleblad lenses. They were not that great when I was using the center portion of them, but with a reducer, that might change. They are much better when used on MF film or sensors.

      I guess that a person could experiment by putting one on a aps-c body with the converter and see, someone has surely tried this.
    18. M camera+ EF to M speed booster+ ducktape+Another EF to M speed booster+kipon adabter hb to canon +hb lens= low megapixel medium format camera :p
      If M5 mark 2 got ibis and pixel shift it wont be even low megapixel

    Leave a comment

    Please log in to your forum account to comment