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    What is the maximum aperture at 400mm on the Canon RF 100-500mm f/4.5-7.1L IS USM?

    By Updated:111 Comments1 Min Read Canon Lens News
    rf100500 - What is the maximum aperture at 400mm on the Canon RF 100-500mm f/4.5-7.1L IS USM?

    A question that I personally wanted to be answered has been answered at The-Digital-Picture with the help of Canon USA.

    The answer is actually quite interesting.

    What is the Canon RF 100-500mm F4.5-7.1 L IS USM Lens's maximum aperture opening at 400mm?

    Answer 1: When the camera is set to 1/3-stop increments, the maximum 400mm aperture is f/6.3.

    Answer 2: When the camera is set to 1/2-stop increments, the maximum 400mm aperture is f/5.6.

    Keep in mind that on variable aperture lenses, the camera doesn't read what the exact aperture is

    I would hypothesize that the lens is actually something like f/6 at 400mm and the increment settings just decide how the camera reads the aperture. Rarely are apertures 100% accurate on variable aperture lenses. I haven't yet seen a patent with this exact optical formula to know what it is at 400mm from a design point of view.

    Hopefully, Canon makes it easy to switch between 1/3 and 1/2 increments when using the Canon RF 100-500mm f/4.5-7.1L IS USM with your EOS R5 & EOS R6.

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    111 comments

    2. Yeah.. as in camera displays / reports the aperture being f/5.6 as a rounded number while in reality it would be at f/6.3 Right?
      Feels like that is the case. Someone will test and calculate the T stop, which will be a better indicator.
    3. In reality, it likely means real, physical aperture is something like F6 or 6.1. When in third top mode the nearest number to round to is 6.3. In half stop mode, it is 5.6.
    4. Feels like that is the case. Someone will test and calculate the T stop, which will be a better indicator.
      A bit like wide end forced distortion correction on the RF 24-105 STM. You won’t know unless you are really looked for it ;)
    5. Yeah.. as in camera displays / reports the aperture being f/5.6 as a rounded number while in reality it would be at f/6.3 Right?

      They're both rounded, obviously. The apparent aperture size varies continuously and not in any sort of increments.
    6. They're both rounded, obviously. The apparent aperture size varies continuously and not in any sort of increments.
      Yup, the Next half stop after f5.6 is f/6.7. Sooo... f/6.0 or f/6.1 could be the number that being rounded down to f/5.6 going in half stops and rounded up to f/6.3 if going in 1/3 of a stop. With f/6.1 being the likely real number. Not bad though. Not bad at all.
    7. Didn’t Gordon Laing do a video with this lens? It was 5.6 at something like 360mm? I’d imagine it isn’t a great loss in reach with that aperture considering you now get an extra 100mm on the long end. It seems a relatively small compromise to get the RF benefits too.
    8. Is Canon Rumours Guy being sarcastic with that last bit about changing settings? It’s hard to tell with text.

      Because surely, when it comes to max aperture on variable aperture zooms, the number reflected in the metadata is always a rounded figure. The aperture isn’t mechanically clicking into different positions during the zoom... it’s simply the calculated value based on the entrance pupil in relation to the changing focal length. Right?
    9. The thing to remember is the 100-400 isn't exactly 5.6 at 400mm either. IN fact I think that lens isn't actually 400mm, but I can't recall which variation. Might have ended at like 380mm in actuality. All camera lenses are approximate stops near the ends of their ranges. This is why, as I understand it - and I may not have all the right understanding - cinema lenses are listed in T stops instead. You can take two lenses and know you are getting the same transmittence/light flux on both of them.
    10. The thing to remember is the 100-400 isn't exactly 5.6 at 400mm either. IN fact I think that lens isn't actually 400mm, but I can't recall which variation. Might have ended at like 380mm in actuality. All camera lenses are approximate stops near the ends of their ranges. This is why, as I understand it - and I may not have all the right understanding - cinema lenses are listed in T stops instead. You can take two lenses and know you are getting the same transmittence/light flux on both of them.
      Around 386mm on top of my head..
    11. The thing to remember is the 100-400 isn't exactly 5.6 at 400mm either. IN fact I think that lens isn't actually 400mm, but I can't recall which variation. Might have ended at like 380mm in actuality. All camera lenses are approximate stops near the ends of their ranges. This is why, as I understand it - and I may not have all the right understanding - cinema lenses are listed in T stops instead. You can take two lenses and know you are getting the same transmittence/light flux on both of them.
      What it means to me though is that the lens is not a f/6.6 rounded down to f/6.3 but f6.1 rounded up to f/6.3 when going in 1/3 of a stop. Good.
    13. Didn’t Gordon Laing do a video with this lens? It was 5.6 at something like 360mm? I’d imagine it isn’t a great loss in reach with that aperture considering you now get an extra 100mm on the long end. It seems a relatively small compromise to get the RF benefits too.
      Here it is again as it is most pertinent.
      Cameralabs_100-500mm.png
    14. What it means to me is that the 100-500 will be slightly darker than the 100-400 at 400mm. With the high DR of modern cameras, this is totally irrelevant to me. I shoot RAW, and it's rare that I don't tweak good shots in post. Although I wish that Canon had been more upfront that the light transmission is slightly lower at 400mm, for me it is a reasonable tradeoff if I'm getting equal or better IQ and an extra 100mm of reach in roughly the same-size package. I hear some grumble about not getting 600mm and 6.3 at the long end, but I don't want the extra weight and bulk that's required for those specs when I'm traveling or when I want to do close-up photography. What the extra $700 buys you over the $2000 super-tele-zooms is flexibility (100mm versus 150-200 at the short end), compact size and weight (1.5-2.5lbs saving), closer focusing, and hopefully better IQ throughout the range. For me, these are great benefits.
    16. It would be nice if Canon finally released the manuals of the R5 and R6. Do they expect people to order those camaras without having read the manual? Then we would know how easy it is to change from 1/2 to 1/3 increments and back.
    17. It would be nice if Canon finally released the manuals of the R5 and R6. Do they expect people to order those camaras without having read the manual? Then we would know how easy it is to change from 1/2 to 1/3 increments and back.

      My sarcasm detector is buzzing a little. Manuals would be nice, sure, but for that reason?
    18. It would be nice if Canon finally released the manuals of the R5 and R6. Do they expect people to order those camaras without having read the manual? Then we would know how easy it is to change from 1/2 to 1/3 increments and back.
      I mean, i feel like the acronym RTFM was created precisely because people don't...well...read the manual. LOL

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