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

sobrien

EOS M50
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Apr 26, 2020
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Thinking about it a bit more, the actual/physical aperture of the 100-400 Mark ii at full extension could be something like f/5.9...i.e. above f/5.6 but closer to f/5.6 than f/6.3...and it might not really be 400mm as others have suggested...so taking those two things together it is possible that 100-400 Mark ii at full extension might have the very same physical aperture as the RF 100-500 at that focal length.

Edit in italics for clarification
 
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blackcoffee17

EOS RP
Sep 17, 2014
461
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I think i am happy with the 100-500 apertures. It's still 5.6 at 363mm, i think that's very decent. I am not so happy about the price, was hoping for something a bit cheaper, but the price was expected.
 
Jul 15, 2020
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I calculate that:
f/5.6 at ISO 100 = f/6.3 at ISO 133
f/5.6 at ISO 800 = f/6.3 at ISO 1066
f/5.6 at ISO 3200 = f/6.3 at ISO 4267
quite simply as f/6.3 = 1/3 stop higher than f/5.6 so multiply the f/5.6 value by 1.333 or 4/3. The calculator must be choosing a dialed in value for the camera, which is inaccurate.
Sounds like you have a lot of calculation works to do. LOL
It's a one time thing or you'll do it every time? no offence, Just curious.
My normal concern would be, will the subject fly away, should I keep the shutter speed lower? For staying above 13000feet, a nose bleeding shooter, math and calculation are really no worries.
 

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tron

EOS R5
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Nov 8, 2011
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I think i am happy with the 100-500 apertures. It's still 5.6 at 363mm, i think that's very decent. I am not so happy about the price, was hoping for something a bit cheaper, but the price was expected.
I think Canon may have pushed that lens to the limits. Allow me to explain: They found the "worst" possible tolerable f-stop (f/8 would shock the 100-400 5.6II users - I am one of them -) the least possible acceptable telephoto boost over the 100-400, weight and size very close to 100-400 II and price maybe a little less than upper limit tolerable but which will make EOS Rxxx people "bite".

I know! if I ever upgrade to EOS R5 from my EOS R I would be tempted! OK I would wait for the price to become lower. I am not letting go of my EF teles and/or my 500mmPF any time soon!
 
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AlanF

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Sounds like you have a lot of calculation works to do. LOL
It's a one time thing or you'll do it every time? no offence, Just curious.
My normal concern would be, will the subject fly away, should I keep the shutter speed lower? For staying above 13000feet, a nose bleeding shooter, math and calculation are really no worries.
I spent years looking at my grad students calculations and seeing and checking numbers is second nature. Trouble is that I also have to check facts that puzzle me. Geekish, but I like understanding things. But I like photographing birds and nature far more.
 

AlanF

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Can anyone remember seeing the patent for the 100-500mm? They sometimes have the real focal lengths and apertures on them.
 
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Jul 15, 2020
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That's what I'm talking about too. Unless I'm still misunderstanding you...

No matter what shooting mode you are in, when you go into the ISO selection, you can always pick "auto". I often use that when shooting events, because I want to control the other two factors, but the changing light conditions make auto ISO helpful for staying in the correct exposure ball-park.
Yes, you're right (y) I was wrong on that. EOS 1V, 5D2, don't know how to do that, but the trick works on 5d4.
where is my cognitive bias came from then???
 
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jolyonralph

EOS R5 Mark II
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Aug 25, 2015
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Thinking about it a bit more, the actual/physical aperture of the 100-400 Mark ii at full extension could be something like f/5.9...i.e. above f/5.6 but closer to f/5.6 than f/6.3...and it might not really be 400mm as others have suggested...so taking those two things together it is possible that 100-400 Mark ii at full extension might have the very same physical aperture as the RF 100-500 at that focal length.

Edit in italics for clarification
Probably not, but they're close.

They are rounded down (marketing) so at 1/3 stop intervals something listed as f/5.6 will have a true f value between 5.657 and 6.350

At 1/2 stop intervals the f/5.6 range is 5.657 to 6.727

So, as the EF 100-400 shows f/5.6 at 400mm even on 1/3 stop we can be sure that the actual f value will be between 5.657 and 6.350

Looking back at the EF 100-400 patents (I'm not entirely sure which one is the correct one for the II) shows the f stop at 391mm (the real maximum) is either f/5.8 or f5.85

On the RF 100-500 at 400mm it has to be between 6.350 and 6.727 - which means you're probably looking at around 1/4 of a stop of light reduction - maybe less (especially if you measure at 391mm instead of 400mm).

In any case, the increase in light at the wider range of the lens plus the longer reach and faster focusing surely makes up for this!
 

tron

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Nov 8, 2011
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What IFs are useless but if only Canon made it with just a little larger diameter (and give it a front filter ring of 82mm instead of 77mm so doable) it most probably would be f/6.3 instead of f/7.1 and at the same time it would be f/5.6 at 400mm. But that would impose a toll on its weight so there is that.
 

AlanF

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I just measured the focal length of the 100-400mm II. At a distance of 19.5m and set at 400mm on my 5DSR, the calculated focal length is 383mm, which is in agreement with figures presented here (you can check my calculations: a horizontal line 138mm long at a distance of 19.5m gives an image 681px wide on the sensor, which is 36.0mm and 8688px wide).
 
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BeenThere

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What IFs are useless but if only Canon made it with just a little larger diameter (and give it a front filter ring of 82mm instead of 77mm so doable) it most probably would be f/6.3 instead of f/7.1 and at the same time it would be f/5.6 at 400mm. But that would impose a toll on its weight so there is that.
+$1000.
 
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