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    Patent: Canon RF 15-28mm f/4-5.6 IS and other wide angle optical designs

    By 38 Comments1 Min Read Canon Patents
    patentrfwideslow - Patent: Canon RF 15-28mm f/4-5.6 IS and other wide angle optical designs

    Eventually we're going to see more affordable RF mount lenses from Canon and one of the obvious types of lenses they'll need is an affordable wide angle zoom lens.

    Canon has published a patent for such a lens and others with the aim of making manufacturing easier, which also means less expensive.

    Canon RF 15-28mm f/4-5.6 IS

    • Focal length: 15.40mm-27.50mm
    • F value: 4.00-5.60
    • Half angle of view: 54.51-38.94
    • Image height: 19.00mm-21.64mm
    • Overall length: 103.50mm-103.50mm
    • Back focus: 14.20mm
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    38 comments

    1. So its early and the caffeine hasn't kicked in yet, so I may not be making proper sense of this. But....the largest image height is still 2mm shorter than a FF sensor, correct? I suppose this means this could be the first true RF-s lens design. So far all the APs-c range patents we've seen could do FF at all but the widest angle, and like the 24-240 could do FF with some computational photography applied. If it comes to be a real product I guess it will destroy my theory that they won't have two separate lens lineups for FF and APS-c.

      Brian
    2. So its early and the caffeine hasn't kicked in yet, so I may not be making proper sense of this. But....the largest image height is still 2mm shorter than a FF sensor, correct? I suppose this means this could be the first true RF-s lens design. So far all the APs-c range patents we've seen could do FF at all but the widest angle, and like the 24-240 could do FF with some computational photography applied. If it comes to be a real product I guess it will destroy my theory that they won't have two separate lens lineups for FF and APS-c.

      Brian
      It just means vignetting on the wide end which is pretty typical of RF wide zooms so far
    3. It just means vignetting on the wide end which is pretty typical of RF wide zooms so far
      Presumably heavy distortion at the wide end like the 14-35/4L, 24-240 and 16/2.8. The ‘forced’ digital correction (in-camera and with DPP) requires stretching the corners, so the frame is filled.
    4. For me the also patented 15-28mm f/2.8-4 is actually the most interesting, because it would be lighter and cheaper than "real" 2.8 wide zooms, but still have the extra light at the wide end. If the price and IQ are good, that would be my go to wide angle! Would love to see the Tamron 17-35mm f/2.8-4 on the RF mount if canon doesn´t bring out something like it.
    5. The one surprising thing that I really like about the RF 15-35 f2.8 is that very useful 35mm focal length provides a “normal” lens even when shooting ultra wide. I’m a sucker for ultra wide and may be tempted by a 10-24 but 35 is all around handily without changing lenses.
    6. For the 15-28, if they are able to get pretty good sharpness at the wide end and keep the weight down to say 350 grams and price it at $550 then they may have a winner. Suprised to see length is the same as the 14-35.
    7. I’d wish Canon makes an equivalent of EF-S 10-22 but for full frame. I wouldn’t mind aperture f/5.6-7.1 (for 16-35) but I think it’s possible to make it even smaller and lighter with ML technology. And of course much sharper.
      I don’t understand why this lens would be over 100 mm long.
      (14 or 15 mm would be really nice but I wouldn’t expect that)
    8. I’d wish Canon makes an equivalent of EF-S 10-22 but for full frame. I wouldn’t mind aperture f/5.6-7.1 (for 16-35) but I think it’s possible to make it even smaller and lighter with ML technology. And of course much sharper.
      I don’t understand why this lens would be over 100 mm long.
      (14 or 15 mm would be really nice but I wouldn’t expect that)
      Add half decent close focusing capabilities(similar or better than RF 16mm f2.8) and it would be a great lens for fun macro.
    9. It just means vignetting on the wide end which is pretty typical of RF wide zooms so far

      In other words, another optically compromised wide angle lens for RF from Canon that will be corrected in camera so you don't see how bad it is - just like the RF 14-35/f4L.

      Can't wait to see some non-Canon RF wide angle lenses that hopefully aren't fucked by design like Canon's are.
    10. In other words, another optically compromised wide angle lens for RF from Canon that will be corrected in camera so you don't see how bad it is - just like the RF 14-35/f4L.

      Can't wait to see some non-Canon RF wide angle lenses that hopefully aren't fucked by design like Canon's are.
      That's just the nature of how lenses work, no lens is perfect, even the most expensive ones.

      I'm glad you are still loving the design of the 90D that is before the RF era.
    12. In other words, another optically compromised wide angle lens for RF from Canon that will be corrected in camera so you don't see how bad it is - just like the RF 14-35/f4L.

      Can't wait to see some non-Canon RF wide angle lenses that hopefully aren't fucked by design like Canon's are.
      As a photographer, all I care about is the final image. If the lens can be made cheaper and lighter by having digital correction in camera or automatically done in software, it doesn't bother me a bit. My guess is that most folks would gladly choose lighter and cheaper as well. That's what automatic digital correction is for - to make a cheaper and lighter lens. If the end result is a sharp, quality image, what's the problem?
    13. As a photographer, all I care about is the final image. If the lens can be made cheaper and lighter by having digital correction in camera or automatically done in software, it doesn't bother me a bit. My guess is that most folks would gladly choose lighter and cheaper as well. That's what automatic digital correction is for - to make a cheaper and lighter lens. If the end result is a sharp, quality image, what's the problem?

      The problem is when Canon produces lenses that generate images with severe problems, you aren't getting lenses that are cheaper (maybe lighter.) Look at the cost of the RF 14-35/f4L vs the 16-35 f/4L. 2mm wider, massive increase in distortion and a massive price increase but only 100g weight savings (the weight of a chocolate bar.)

      With this lens, the suggestion is that the image circle doesn't cover the full frame and that's not a problem because in-camera electronics will just correct for the resulting vignetting and distortion. If the camera needs to boost the peripheral parts of the image by 2+ stops, there's no way that can't impact the final image quality. The better the quality of the input, the better the quality of the output.

      With what is effectively MkI lenses for RF from Canon, photographers at the wide end are getting fucked over, pure and simple.
    14. That's just the nature of how lenses work, no lens is perfect, even the most expensive ones.

      I'm glad you are still loving the design of the 90D that is before the RF era.

      At least I can frame the image with the 90D without having to drain the battery.

      The problem isn't the lack of a perfect lens, the problem is that Canon is pursuing lRF lens designs that have significant image quality issues that they're just hand waving away with software - and asking customers to pay more for the privilege of such lenses.
    15. It could be a good travel lens for many. I have given up on carrying regular cameras with me on non-photography trips and now travel with G7X3 - much lighter and fantastic photos. So for me, these lenses are useless. It has to be the best lens for photo-centric trips and paid work with R5, for everything else G7x3 works GREAT.
    16. The problem is when Canon produces lenses that generate images with severe problems, you aren't getting lenses that are cheaper (maybe lighter.) Look at the cost of the RF 14-35/f4L vs the 16-35 f/4L. 2mm wider, massive increase in distortion and a massive price increase but only 100g weight savings (the weight of a chocolate bar.)

      With this lens, the suggestion is that the image circle doesn't cover the full frame and that's not a problem because in-camera electronics will just correct for the resulting vignetting and distortion. If the camera needs to boost the peripheral parts of the image by 2+ stops, there's no way that can't impact the final image quality. The better the quality of the input, the better the quality of the output.

      With what is effectively MkI lenses for RF from Canon, photographers at the wide end are getting fucked over, pure and simple.
      I would accept 14-35's design if it was much cheaper than it is. Not when it costs almost as a much better design 2.8L lens.
      Anyway people who do not have EF lenses (or the RF15-35) and can afford it may as well buy it. I understand they will be happy with its IQ and they will soon forget how much they paid for it.
    17. Regarding current travel lenses I use either 5DIV with 16-35 4L IS (with or without 24-105 or G7XII) or 200D with 10-18 with 15-85 sometimes. R5 is busy connected to 100-500 and it's not worth to get a second R5 and 14-35 as a travel combo.
    18. With what is effectively MkI lenses for RF from Canon, photographers at the wide end are getting fucked over, pure and simple.
      There are EF L-series lenses with >4 stops of vignetting. There are EF L-series lenses with >3% barrel distortion. Those lenses produce images with very noticeable artifacts unless they are digitally corrected.

      In the overlapping part of the zoom range, the RF 14-35/4 is optically quite similar to the EF 16-35/4. The RF lens offers an extra 2-2.5mm on the wide end, and it requires both more money and digital correction to get it.

      I’m not sure if that offends you because you abhor digitally processing images, or because the higher cost of the lens is beyond your means. But for those photographers who use modern image processing techniques (which includes those shooting in-camera jpgs) and have the wherewithal to buy the lens, no one is getting screwed over.
    19. @neuroanatomist Indeed TDP shows them similar good catch. The only thing is that 16-35 has visibly less vignetting than the RF version. This may or may not be a problem depending on the ISO one shoots at. If someone wants to shoot at low light with no tripod or with tripod but high iso (say for astro landscape work) then this would be a problem. Unfortunately the same applies to RF15-35 too. It is worse that the EF 16-35 2.8L III which is worse than 14mm 2.8L II.

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