A couple of optical formula patents from Sigma have appeared. There is no mention of mount types in these optical formulas, so we'll have to wait and see if either will ever make its way to the RF mount.

First up is a 50-140mm f/2.8 for APS-C equipped cameras. It would basically give you a 70-200 f/2.8 equivalent in APS-C terms (80-220).

The second is an external zoom 70-200mm f/2.8 for full-frame cameras. This sort of lens design makes some sense for size and balance with smaller mirrorless cameras, but there is a large number of shooters that much prefer an internal zoom 70-200 f/2.8.

Sigma 50-140mm f/2.8 DC (APS-C)

  • Focal length: 50.50mm – 136.50mm
  • F-number: 2.92
  • Half angle of view: 30.62° – 11.40°
  • Height: 14.20mm
  • Length: 125.00mm – 145.00mm

Sigma 70-200mm f/2.8 (Full-Frame)

  • Focal length: 72.00mm – 194.10mm
  • F-number: 2.92
  • Half angle of view: 32.92° – 12.12°
  • Height: 21.63mm
  • Length: 168.00mm – 203.60mm

This patent information was found at asobinet.

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54 comments

  1. With every feature comes a detriment. I love the compact size and weight of the revolutionary RF 70-200 f2.8 LIS. At 70mm it takes up little bag space. However, it's weight saving technology could easily have been delivered into the Mk III ef version. A clear indicator that Canon have been holding back on EF lens development for quite a few years before the RF mount was released.
    The issue with the RF 70-200 on the mirrorless mount is very shallow disctance between the rear element and the sensor. It requires some really complex aspherical last group lens elements that DSLR lenses didn't require. It also precludes the use of teleconverters and for me this is a massive reduciton in versatility and appeal to a 70-200mm f2.8 lens. The ability to use a 1.4x and have a 100-300mm f4 or a 2x and have a very capable 140-400mm lens is a massive camera bag saving bonus. It's not just the space betweenthe rear element, it's the fact that the rear elements bend the light rays specifically for a close proximity sensor. Even if upi could put a TC in there, it would dramatically reduce image quality and increase teleconverter lens design complexity, trying to retro mod these last elements of the 70-200. It's also why we aren't going to get any Canon RF extension tubes anytime soon.
    As much as I adore the new RF version...the lack of teleconverter use is a deal breaker for me. I regularly use TC's on my ef 70-200 II LIS as well as a 12mm extension tube for flowers and floral close ups.
    So for me, this lens design isn't a great fit. I aslo have a very low opinion of Sigma's ability to make a great 70-200 f2.8 mk1. They have pushed out so many designs over the years making marginal adjustments to something that should have been right 1st time. Talk about !measure once and cut twice".
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  2. With every feature comes a detriment. I love the compact size and weight of the revolutionary RF 70-200 f2.8 LIS. At 70mm it takes up little bag space. However, it's weight saving technology could easily have been delivered into the Mk III ef version. A clear indicator that Canon have been holding back on EF lens development for quite a few years before the RF mount was released.
    The issue with the RF 70-200 on the mirrorless mount is very shallow disctance between the rear element and the sensor. It requires some really complex aspherical last group lens elements that DSLR lenses didn't require. It also precludes the use of teleconverters and for me this is a massive reduciton in versatility and appeal to a 70-200mm f2.8 lens. The ability to use a 1.4x and have a 100-300mm f4 or a 2x and have a very capable 140-400mm lens is a massive camera bag saving bonus. It's not just the space betweenthe rear element, it's the fact that the rear elements bend the light rays specifically for a close proximity sensor. Even if upi could put a TC in there, it would dramatically reduce image quality and increase teleconverter lens design complexity, trying to retro mod these last elements of the 70-200. It's also why we aren't going to get any Canon RF extension tubes anytime soon.
    As much as I adore the new RF version...the lack of teleconverter use is a deal breaker for me. I regularly use TC's on my ef 70-200 II LIS as well as a 12mm extension tube for flowers and floral close ups.
    So for me, this lens design isn't a great fit. I aslo have a very low opinion of Sigma's ability to make a great 70-200 f2.8 mk1. They have pushed out so many designs over the years making marginal adjustments to something that should have been right 1st time. Talk about !measure once and cut twice".

    I wouldn't be surprised to see a second 70-200 f/2.8 with an internal zoom and TC compatibility added to the line-up in the future. At one point the EF line-up had 4 70-200s in production.
    • 0
  3. I always saw the 70-200 as the second standard zoom next to the 24-70, but I was surprised that on my recent trip to several cities I hardly ever used the 70-200. So I will pretty much retire it and it will stay at home on any future trips unless they involve sports events like the Olympics next year. My 100-400 II has a lot more reach and a better image quality. Of course new 70-200 lenses will be sharper than my old 70-200 f/2.8 IS (the first version), but I feel like I am pretty much done with that focal range. Sometimes I might need a focal length between 70 and 100, but then I can still crop and I might replace the 24-70 with a 24-105 one day.

    At good light, the smallest f-stop I use usually is f/8, because I want to minimize bokeh. Others might make use of f/2.8 all the time.

    I wonder how much Sigma will be asking for that lens. As the Canon version is around $2,800, imagine Sigma comes with a $1,500 version with a good image quality. Or will Canon demand very high fees from Sigma for the access to the RF mount?
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  4. It's also why we aren't going to get any Canon RF extension tubes anytime soon.

    I bought Meike tubes for 36€ on Amazon, and they work like a charm, both on RF lenses (especially on the 85 f2 Macro, even if I just sold it yesterday) and on EF lenses (installed before the RF to EF converter); so from that point of view I don't feel the need of Canon own tubes now.


    I agree abut the TC on 70-200; even if I very rarely use the 2x extender on my EF 70-200 2.8 non-IS, I'm glad I've the option to do it if needed.
    • 0
  5. I bought Meike tubes for 36€ on Amazon, and they work like a charm, both on RF lenses (especially on the 85 f2 Macro, even if I just sold it yesterday) and on EF lenses (installed before the RF to EF converter); so from that point of view I don't feel the need of Canon own tubes now.


    I agree abut the TC on 70-200; even if I very rarely use the 2x extender on my EF 70-200 2.8 non-IS, I'm glad I've the option to do it if needed.
    It's nice to have a constant aperture, some folks aren't crazy about things like 4.5-7.1 or having to buy two lenses, especially if the longer lens is used less often. Canon accountants like it though.
    • 0
  6. First up is a 50-140mm f/2.8 for APS-C equipped cameras. It would basically give you a 70-200 f/2.8 equivalent in APS-C terms (80-220).
    80-220 is only the equivalent for Canon, who use smaller 1.6 CF APS-C sensors. The other major vendors (Sony, Fuji, Nikon, etc.) use larger 1.5 CF sensors, and for them it would be 75-210 equivalent.

    Either way, it's exciting to see new, innovative APS-C lens formulae being developed (at least patented, if nothing else). I'm skeptical of how soon we'll see third party AF lenses for Canon RF, if ever, but that's a subject for a different thread...
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  7. 80-220 is only the equivalent for Canon, who use smaller 1.6 CF APS-C sensors. The other major vendors (Sony, Fuji, Nikon, etc.) use larger 1.5 CF sensors, and for them it would be 75-210 equivalent.

    Either way, it's exciting to see new, innovative APS-C lens formulae being developed (at least patented, if nothing else). I'm skeptical of how soon we'll see third party AF lenses for Canon RF, if ever, but that's a subject for a different thread...
    I speak in Canon terms for the readers here, but thanks for adding that tidbit of info.
    • 0
  8. I speak in Canon terms for the readers here, but thanks for adding that tidbit of info.
    Yah, I figured, since this is obviously a Canon-centric site. I'm ambivalent about Canon's different factor. It's not a problem in most practical situations, but 1.5 makes the mental math easier!

    In the old Popular Photography magazine lens reviews, they would measure the actual focal length on an optical bench. As I recall, most zooms lenses differed from their rated ranges by 5-10 mm at each end anyway.
    • 0
  9. I have an old Tokina 50-135/2.8. It's a nice lens in terms of focal lengths and usefulness. It has primitive AF and the optical performance isn't quite up to today's standards, but still - a nice lens. I think Sigma's offering will do well.
    • 0
  10. I own Sigma’s 24-70mm f2.8 Art DG DN and its more than good enough that I don’t feel the need to pay double to get Sony’s MKII equivalent. The Sony is the better lens but optically there isn’t enough of a difference that I can personally justify the cost.

    The upcoming 70-200mm f2.8 DG DN I expect to be excellent like their recent primes.
    • 0
  11. Sigma has been working on the 70-200mm F2.8 mirrorless lens forever now. I guess it was last year when they stated that they had to start over the development process after they had put in two years of work already. I guess the RF 70-200mm and the new Sony GM 70-200mm mkii are so good, Sigma felt they couldn't compete just yet.
    • 0
  12. With every feature comes a detriment. I love the compact size and weight of the revolutionary RF 70-200 f2.8 LIS. At 70mm it takes up little bag space. However, it's weight saving technology could easily have been delivered into the Mk III ef version. A clear indicator that Canon have been holding back on EF lens development for quite a few years before the RF mount was released.
    The issue with the RF 70-200 on the mirrorless mount is very shallow disctance between the rear element and the sensor. It requires some really complex aspherical last group lens elements that DSLR lenses didn't require. It also precludes the use of teleconverters and for me this is a massive reduciton in versatility and appeal to a 70-200mm f2.8 lens. The ability to use a 1.4x and have a 100-300mm f4 or a 2x and have a very capable 140-400mm lens is a massive camera bag saving bonus. It's not just the space betweenthe rear element, it's the fact that the rear elements bend the light rays specifically for a close proximity sensor. Even if upi could put a TC in there, it would dramatically reduce image quality and increase teleconverter lens design complexity, trying to retro mod these last elements of the 70-200. It's also why we aren't going to get any Canon RF extension tubes anytime soon.
    As much as I adore the new RF version...the lack of teleconverter use is a deal breaker for me. I regularly use TC's on my ef 70-200 II LIS as well as a 12mm extension tube for flowers and floral close ups.
    So for me, this lens design isn't a great fit. I aslo have a very low opinion of Sigma's ability to make a great 70-200 f2.8 mk1. They have pushed out so many designs over the years making marginal adjustments to something that should have been right 1st time. Talk about !measure once and cut twice".

    We all have our priorities. I absolutely LOVE the compact design of the RF 70-200 f/2.8. I probably would have settled for the f/4 version if not for the ability to squeeze my R6 and this lens into a small bag for taking action shots of my children doing dance and show choir. When I need more reach, I use a different lens. Packing both for trips is fine as the 70-200 is smaller than my Tamron 15-30 f/2.8.
    • 0
  13. Yah, I figured, since this is obviously a Canon-centric site. I'm ambivalent about Canon's different factor. It's not a problem in most practical situations, but 1.5 makes the mental math easier!

    In the old Popular Photography magazine lens reviews, they would measure the actual focal length on an optical bench. As I recall, most zooms lenses differed from their rated ranges by 5-10 mm at each end anyway.
    The recent announcement of the Nikon 180-600 made me think of FL rounding. If there is 5% error allowed for rounding (number I made up out of nothing), one could market a 189-572 as a 180-600 or a 191-572 as the 200-600. It's all silly as I doubt I could tell any difference between 180 and 200 in real world use anyway.
    • 0
  14. Sigma has been working on the 70-200mm F2.8 mirrorless lens forever now. I guess it was last year when they stated that they had to start over the development process after they had put in two years of work already. I guess the RF 70-200mm and the new Sony GM 70-200mm mkii are so good, Sigma felt they couldn't compete just yet.
    There was a rumour that Sigma had a design but then scrapped it and started again. No idea if this is true but certainly possible.
    • 0
  15. Hmm, that surprised me. I thought they'd take this opportunity to differentiate their product and produce an internal zoom option for the 70-200. Curious how this all pans out for third-party manufacturers.
    • 0
  16. while a more realistically priced 70-200 is very welcome, being an external zoom is not what I was hoping for. While compact is a good thing, we have seen this can be achieved in relatively small form factors while maintaining internal moving elements.
    • 0

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