Patent: Optical formulas for a trio of wide f/1.8 prime lenses for the RF-S mount

Canon Rumors Guy

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  • Jul 20, 2010
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    A new patent showing off some lens element coating to help with ghosting and other anomalies has appeared alongside optical formulas for what appears to be RF-S prime lenses.
    Below are the three prime lens designs shown in the patent, we wouldn’t be surprised for one of these to hit the market as a consumer product.
    Canon RF-S 21mm f/1.8

    Focal length: 20.60mm
    F-value: 1.85
    Half angle of view: 46.4°
    Image height: 18.71mm
    Overall length: 84.87mm
    Back focus: 11.00mm

    Canon RF-S 24mm f/1.8

    Focal length: 24,72mm
    F-value: 1.85
    Half angle of view: 41.2°
    Image height: 19.34mm
    Total length: 81.00mm
    Back focus: 11.00mm

    Canon RF-S 28mm f/1.8

    Focal length: 28.60mm
    F-value: 1.85
    Half angle of view: 37,1°
    Image height: 20.15mm
    Total length: 81.00mm
    Back focus: 13.20mm

    Continue reading...
     
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    entoman

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    Is there such a thing as an "RF-S mount"?

    I thought that "RF-S" lenses would fit on normal RF mount, as well as on crop cameras, but that full-frame models would electronically recognise RF-S lenses, and crop the frame accordingly?

    Or have I got it wrong?
     
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    unfocused

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    Is there such a thing as an "RF-S mount"?

    I thought that "RF-S" lenses would fit on normal RF mount, as well as on crop cameras, but that full-frame models would electronically recognise RF-S lenses, and crop the frame accordingly?

    Or have I got it wrong?
    That's correct. However, I expect we will see a lot of people/sites referring to RF-S lenses as having an RF-S "mount." Not entirely accurate, but Canon Rumors has never claimed to be a research paper.
     
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    That's correct. However, I expect we will see a lot of people/sites referring to RF-S lenses as having an RF-S "mount." Not entirely accurate, but Canon Rumors has never claimed to be a research paper.
    Maybe it's because Canon in their own material refers to it as the "RF-S Mount?" (See link: https://www.usa.canon.com/shop/p/rf-s18-150mm-f3-5-6-3-is-stm?color=Black&type=New)

    They do also specifically mention that it fits on full frame cameras in crop mode. "This lens was designed with smaller APS-C sensors in mind, and when attached to a full frame EOS R camera, automatically enables the 1.6x crop mode. It offers 100% x 100% Dual Pixel CMOS AF coverage for APS-C sensors, and 80% x 80% Dual Pixel CMOS AF coverage for Full Frame sensors (in crop mode)."
     
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    unfocused

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    Maybe it's because Canon in their own material refers to it as the "RF-S Mount?" (See link: https://www.usa.canon.com/shop/p/rf-s18-150mm-f3-5-6-3-is-stm?color=Black&type=New)

    They do also specifically mention that it fits on full frame cameras in crop mode. "This lens was designed with smaller APS-C sensors in mind, and when attached to a full frame EOS R camera, automatically enables the 1.6x crop mode. It offers 100% x 100% Dual Pixel CMOS AF coverage for APS-C sensors, and 80% x 80% Dual Pixel CMOS AF coverage for Full Frame sensors (in crop mode)."
    Good point. If I were Canon I'm not sure I would refer to it as an RF-S "mount," but it's their company and they can do what they want. (I'm not sure how I would refer to the mount though.) Regardless, it's kind of an esoteric and pointless distinction, which is perfect for forum discussions.
     
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    Good point. If I were Canon I'm not sure I would refer to it as an RF-S "mount," but it's their company and they can do what they want. (I'm not sure how I would refer to the mount though.) Regardless, it's kind of an esoteric and pointless distinction, which is perfect for forum discussions.
    Interestingly, looking at the tech specs for the R10, they refer to the lens mount as the RF lens mount, and then under "compatible lenses" refer to the "Canon RF-S/RF lens group"
     
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    mxwphoto

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    Calling it a RF-S mount is more clear and better than calling it RF mount but for crop sensor cameras. I think Canon did the same for EF-S lenses as well. This makes things less ambiguous and provides clear delineation from RF full frame lenses.

    I would imagine Canon most likely coming out with the 28mm (45mm equiv) but they could also spring for the 20mm (33mm equiv). Doubtful there's space for all 3 though.
     
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    unfocused

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    Calling it a RF-S mount is more clear and better than calling it RF mount but for crop sensor cameras. I think Canon did the same for EF-S lenses as well. This makes things less ambiguous and provides clear delineation from RF full frame lenses.

    I would imagine Canon most likely coming out with the 28mm (45mm equiv) but they could also spring for the 20mm (33mm equiv). Doubtful there's space for all 3 though.
    I think the (very minor) distinction here is that EF-S lenses were clearly a different "mount" that could not be placed on a full-frame body, whereas all RF lenses, whether RF-S or RF, can be mounted on any R body. Thus in a technical sense it's not really a different "mount." However, it's really an esoteric discussion.
     
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    mxwphoto

    R6 and be there
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    I think the (very minor) distinction here is that EF-S lenses were clearly a different "mount" that could not be placed on a full-frame body, whereas all RF lenses, whether RF-S or RF, can be mounted on any R body. Thus in a technical sense it's not really a different "mount." However, it's really an esoteric discussion.
    Indeed the masses won't care much on the merits of this debate, relegating it to rumor mill discussion posts.

    While we are discussing technicalities, I would like to add that EF-S can be mounted on a full frame DSLR successfully if the mirror is in lock-up mode/silent shutter engaged. It would be good for video recording or one photo before you have to remove the lens to prevent the mirror slap damage.
     
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    David - Sydney

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    Still no ultra wide angle RF-S lenses though.
    IMHO, RF-S lenses will be made to suit the build/cost/etc level of the lower end R mount bodies so f1.8 seems to be different to that assumption.

    I would be very surprised to see a RF-S lens that was L quality for instance. Has any EF-S lens been wider than f2.8?
     
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    f119a

    My Cars Always Break Down
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  • Jun 18, 2013
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    Is there such a thing as an "RF-S mount"?

    I thought that "RF-S" lenses would fit on normal RF mount, as well as on crop cameras, but that full-frame models would electronically recognise RF-S lenses, and crop the frame accordingly?

    Or have I got it wrong?
    the CR guy got them wrong.
    We checked this patent like a month ago and the 24mm design is the current RF24
    1661234342060.jpeg
     
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    LogicExtremist

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    Would like to see replacements for EF-S 10-18, 35mm and 60mm lens for RF-S along with tele zoom(longer than 55-250mm) lens.
    The EF-S 10-8mm and 55-250mm were lenses that punched well above their weight, and provided great image quality for their price. Even if Canon didn't put metal lens mounts on either (to remind buyers they're using a cheaper lens) :mad: those lenses really delivered. It would be great to see RF-S versions with some kind of improvements (and not darker in aperture) at such good prices. :)
     
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