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

Antono Refa

EOS R
Mar 26, 2014
1,030
234
And for what it is worth, memory is Canon calculates f stops in camera in tenths, since early EF days. Those wishing for the info in print may want to check specs for Cinema EOS and EF lenses.
Why would Canon calculate f stops in tenths of a stop? Did Canon ever make stills cameras that allowed changing the aperture in anything but half or full stops?
 

SteveC

R5
Sep 3, 2019
1,180
943
Why would Canon calculate f stops in tenths of a stop? Did Canon ever make stills cameras that allowed changing the aperture in anything but half or full stops?
I don't know what he meant by this. But I am not going to assume that he meant tenths of a stop when he only said tenths.
 

SecureGSM

2 x 5D IV
Feb 26, 2017
2,261
1,106
I am trying to make sense of why there is a difference when using 1/3rd rather half stops. The first is to note that f/4 to f/7.1 can be divided nicely into five 1/3rd stops: 7.1 - 6.3 - 5.6 - 5.0 - 4.5, with values we are all used to seeing. The progression in 0.5 stops doesn't fit, e.g. 7.1 - 6.0 - 5.0 - 4.2 is the progressive increase in 1/2s and doesn't use f-numbers that are usually seen. Or, 4.5 - 5.3 - 6.3 - 7.4 is a similar bad fit. A plot of f-number against focal length based on when the f-number starts on the Cameralabs chart gives a nice straight line. All this suggests to me that the 1/3rd stops are more realistic, and the 1/2 stops are just numbers spewed out by Canon to be ones we are used to seeing, like 5.6, and aren't real.

View attachment 191347
Yes, it’s likely f/6.1 (T6.1) in reality rounded down to f/5.6 in 1/2 stop steps or up to f/6.3 in 1/3 stop steps.
 
Jul 15, 2020
6
1
f7.1 is not fast enough.
For wild life photograph you'll have to boost ISO to 6400, even in "good light condition". not a good idea to mess with ISO over 3200.
I use D5, yes I was a traitor :-/ (finger cross for R5)
I hope Canon can make a lenses faster while still within budget, like Sony 200-600 f5.6-6.3, which at 600mm you got f6.3. is that price unreachable? Not at all.
Mainly, its for marketing consideration, that's why I will keep my 100-400 mk II. Both are excellent lenses I believe.
Another question is, can R5 replace or challenge their flagship, like 1dx III? Not a chance.
Manual + auto ISO(my favorite shooting mode), they just won't let you have that.
Still, for marketing reason.
 

Joules

EOS R
Jul 16, 2017
916
1,009
Hamburg, Germany
I agree that all of this is silly. It's splitting hairs. But, doing it in such an odd way.

So, what is the actual focal length of the EF 100-400 L II when set to 400 mm? I know somebody measured it at some point. Can't remember where that was, don't have time to find it. The point is, we're discussing the inaccuracies of the stated f/ value, while ignoring the inaccuracies in the stated focal length. If you want to split hairs, do it right and compare apples to apples. Really, without shooting side by side pictures taken at the same FoV from both lenses and comparing the actual image qualities rather than the numbers, I can't see any information of value coming out of this discussion.
 

CJudge

EOS M6 Mark II
Mar 22, 2019
60
75
Ireland
www.colin-judge.com
This whole discussion makes me wish cameras let you adjust their internal rounding in higher-granularity increments like 1/10 (or finer) of a stop, we'd probably learn a lot about our lenses if they did. Likely not practical for real-world usage, however - plus it would probably expose quite a few creative marketing shenanigans - so it'll never happen.
I know that in my EOS R, in movie mode, it’s possible to set the aperture control to 1/8th stop increments. Not available in stills mode, but as you said it would be impractical.
 
Jul 15, 2020
6
1
What are you talking about? Every Canon I’ve ever owned, including my EOS R, has let me shoot Manual + auto ISO.
Sorry, my bad. To make it clear, what I mean is: "Manual mode (you decide f number as well as shutter speed) and set ISO to Auto", then let the camera to decide the proper exposure. Try that one, I don't think any non-flagship camera has that.
 

Joules

EOS R
Jul 16, 2017
916
1,009
Hamburg, Germany
Sorry, my bad. To make it clear, what I mean is: "Manual mode (you decide f number as well as shutter speed) and set ISO to Auto", then let the camera to decide the proper exposure. Try that one, I don't think any non-flagship camera has that.
And I think you are wrong.

80D, Mode dial set to M so that I can set the shutter speed and f-number I want and ISO set to Auto (with the option to restrict the range via menu) works perfectly fine.
 

Antono Refa

EOS R
Mar 26, 2014
1,030
234
I don't know what he meant by this. But I am not going to assume that he meant tenths of a stop when he only said tenths.
OK, then tenths of what? If he means one digit after the decimal point, I think that's practically the industry standard. I don't recall ever seeing f & t stops given with two or more digits after the decimal point, outside of photography 101 explanations of the subject.
 

navastronia

EOS RP + 5D Classic
Aug 31, 2018
562
626
Sorry, my bad. To make it clear, what I mean is: "Manual mode (you decide f number as well as shutter speed) and set ISO to Auto", then let the camera to decide the proper exposure. Try that one, I don't think any non-flagship camera has that.
They do. My $1099 EOS RP does it.
 

Rbus

5D Mk3 5D Mk4 EF16-35 2.8L, EF24-105 F4L, EF100-40
Aug 4, 2016
9
8
New Zealand
It would be nice if Canon finally released the manuals of the R5 and R6. Do they expect people to order those cameras without having read the manual? Then we would know how easy it is to change from 1/2 to 1/3 increments and back.
If it is like all the other Canon Camera's I have owned then it will be in the menu's and easy to to change, although I cannot understand why you would want to after your initial setup.
 

Steve Balcombe

Too much gear
Aug 1, 2014
247
164
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.
Exactly right - so maybe a 1/4 stop slower than the 100-400 at that specific focal length. And the comparison chart which somebody put together shows that overall there is very little difference between the EF 100-400 and the RF 100-500 through the range - except for 401-500 mm of course. The whole thing is a storm in a teacup.
 

Codebunny

EOS RP
Sep 5, 2018
478
427
f7.1 is not fast enough.
For wild life photograph you'll have to boost ISO to 6400, even in "good light condition". not a good idea to mess with ISO over 3200.
I use D5, yes I was a traitor :-/ (finger cross for R5)
I hope Canon can make a lenses faster while still within budget, like Sony 200-600 f5.6-6.3, which at 600mm you got f6.3. is that price unreachable? Not at all.
Mainly, its for marketing consideration, that's why I will keep my 100-400 mk II. Both are excellent lenses I believe.
Another question is, can R5 replace or challenge their flagship, like 1dx III? Not a chance.
Manual + auto ISO(my favorite shooting mode), they just won't let you have that.
Still, for marketing reason.
If f/7.1 isn’t fast enough I fail to see why 1/3rd of a stop will make a difference. ISO 6400 is unacceptable but ISO 5000 is? Not forgetting there will be a large IQ difference between a Canon L lens and a consumer 200-600mm.
 
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Codebunny

EOS RP
Sep 5, 2018
478
427
I agree that all of this is silly. It's splitting hairs. But, doing it in such an odd way.

So, what is the actual focal length of the EF 100-400 L II when set to 400 mm? I know somebody measured it at some point. Can't remember where that was, don't have time to find it. The point is, we're discussing the inaccuracies of the stated f/ value, while ignoring the inaccuracies in the stated focal length. If you want to split hairs, do it right and compare apples to apples. Really, without shooting side by side pictures taken at the same FoV from both lenses and comparing the actual image qualities rather than the numbers, I can't see any information of value coming out of this discussion.
About 380mm is what I recall.
 

tron

EOS R5
Nov 8, 2011
4,552
773
OK maybe f/7.1 is something in between. Not "fast enough" but not "too slow" either.

Slightly off topic but the f/5.6 of Nikon 500mm 5.6E PF is better though :)

BUT truth be told: if I ever upgraded my R to R5 I would be curious about 100-500... (and it has that 100 to 499mm range too...)
 
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CJudge

EOS M6 Mark II
Mar 22, 2019
60
75
Ireland
www.colin-judge.com
Sorry, my bad. To make it clear, what I mean is: "Manual mode (you decide f number as well as shutter speed) and set ISO to Auto", then let the camera to decide the proper exposure. Try that one, I don't think any non-flagship camera has that.
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.
 
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CJudge

EOS M6 Mark II
Mar 22, 2019
60
75
Ireland
www.colin-judge.com
If f/7.1 isn’t fast enough I fail to see why 1/3rd of a stop will make a difference. ISO 6400 is unacceptable but ISO 5000 is? Not forgetting there will be a large IQ difference between a Canon L lens and a consumer 200-600mm.
I've seen people on other sites make similar complaints about the upcoming 85mm f/2. Claiming that f/1.8 is a wonderful portrait option, but f/2 is "unusable" for portraits. I swear, some people get way too hung up on 1/3rd of a stop.

In practical use, I could barely see a DOF difference between my old EF 24-70 f/2.8L ii and the RF 28-70 f/2. And that's coming from someone who happily bought the RF lens after testing! Rendering will take precedence over max aperture any day of the week. Which is why the 100mm f/2.8L remains my favourite lens. (It just so happens that the RF 28-70 ticks both boxes)
 
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