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

1D4

EOS M50
Jun 5, 2020
46
104
I was putting emphasis on friendliness! It seems you were written in this forum mainly to argue with people (judging by the other thread you yourself mentioned). Every person has different criteria for their needs in wildlife and birding photography just like any other kind of photography. With this in mind I do not need to have your permission to comment on this thread. And don't put words in my mouth. Once more - since you do not seem to have read that - I myself mentioned the 100-499 range advantage of Canon's RF lens).

EDIT: And another member in this forum mentioned D5 and yet another SONY 200-600. Should they get your permission too?
It's amazing you looked through my post history and concluded I mainly argue with people. You should probably look again and not cherry pick the one or two times I've DISAGREED with someone who was making an illogical statement.

AGAIN, thanks for painting me as "forum police" when that's just because you totally misinterpreted (and continue to misinterpret) what I said. I'm done talking to you.
 

scyrene

EOS R6
Dec 4, 2013
2,781
901
UK
www.flickr.com
For those of us who are interested, it's not nitpicking but a desire to understand how our gear works and how to squeeze the best out of it. You don't have to understand much at all to get good images out of a camera or create works of art, but the technology is of great interest as well if you have a scientific bent.
With all due respect that doesn't answer my question - if nobody can reliably tell a difference between 1/3 of a stop exposure change due to different apertures compensated by ISO or shutter speed, then how does it make a practical difference? I don't think 'nitpicking' is mischaracterisation of most of the discussion regarding differences between the two lenses.
 
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BeenThere

EOS R
Sep 4, 2012
1,086
502
For those of us who are interested, it's not nitpicking but a desire to understand how our gear works and how to squeeze the best out of it. You don't have to understand much at all to get good images out of a camera or create works of art, but the technology is of great interest as well if you have a scientific bent.
I have to disagree that “You don’t have to understand much at all to...... create works of art”.
 

SteveC

R5
Sep 3, 2019
1,117
876
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.
If they do work in tenths of a stop, that's going to end up being kind of sloppy as a tenth does not go into a third. If they want to use some small fraction of a stop to work in, it ought to be one that is a divisor of the fractions they show publicly, so 1/6th (or any division there of: 1/12th, 1/18, etc).
 

tron

EOS R5
Nov 8, 2011
4,547
773
If they do work in tenths of a stop, that's going to end up being kind of sloppy as a tenth does not go into a third. If they want to use some small fraction of a stop to work in, it ought to be one that is a divisor of the fractions they show publicly, so 1/6th (or any division there of: 1/12th, 1/18, etc).
This seems interesting! Back in the analog days EOS620 with Technical Back E could bracket in 1/4th of a stop steps!
 

tron

EOS R5
Nov 8, 2011
4,547
773
It's amazing you looked through my post history and concluded I mainly argue with people. You should probably look again and not cherry pick the one or two times I've DISAGREED with someone who was making an illogical statement.

AGAIN, thanks for painting me as "forum police" when that's just because you totally misinterpreted (and continue to misinterpret) what I said. I'm done talking to you.
Although I agree with you mostly on 200-500 issue the price point is not illogical at all. Not everyone can pay a lot and if they already have a Nikon getting 200-500 is not illogical. There is no absolute truth you know.
 

Billybob

800mm f/11 because a cellphone isn't long enough!
May 22, 2016
93
128
D5, f/7.1 speed 1/1600s at morning, around 8 or 9, can't remember accurately.(for wild life that's a "good light condition", normally I do not walk around in the noon so does most of the animals)...chose f/7.1 to keep both birds in focus, Manual mode, ISO automatically boost to 6400.
For online post or web use that's fine, but I do wish I could stay NO higher than ISO 3200, mainly because of the COLOR not the noise.

For M+Auto ISO, I use from EOS 1V, 5d Mark II, Mark IV...those combinations are different from flagship such as D5. That's my personal experience, but possibly I didn't study the user manual carefully, therefore I maybe use them "differently"
I didn't realize it was so easy to post files. These four were taken between 8:30 and 10am. The osprey shots were taken at f/8, 1/2000s and iso 800 and 2500. The lack of acuity is due to severe cropping rather than inadequate light. The other two shots were taken at f/7.1, 1/1600s, iso 800.

I'm not a big fan of auto ISO especially with cameras that are essentially ISO invariant above ISO 400 or 640. Thus, unless I totally blow the shot, it is easily correct in post. My experience with auto ISO is that it tends to raise the ISO too much. Of course, I could cap auto ISO at 1/3200, but I'm satisfied with my workflow.

Again, I have no problem keeping my shots (much) below ISO 3200 even at f/7.1 and f/8.0. I have a good idea what ISO is appropriate for light conditions, so I rarely have to raise exposure more than 1 stop in post.
 

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AlanF

Stay alert, control the camera, save photos
Aug 16, 2012
6,832
5,872
With all due respect that doesn't answer my question - if nobody can reliably tell a difference between 1/3 of a stop exposure change due to different apertures compensated by ISO or shutter speed, then how does it make a practical difference? I don't think 'nitpicking' is mischaracterisation of most of the discussion regarding differences between the two lenses.
This thread is: "What is the maximum aperture at 400mm on the Canon RF 100-500mm f/4.5-7.1L IS USM?"
If you are not interested in discussing it because it is "nitpicking" and makes no practical difference, then fair enough, it's your choice. But, then why bother to post in it. Leave it to those who are interested in knowing.
 
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AlanF

Stay alert, control the camera, save photos
Aug 16, 2012
6,832
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I didn't realize it was so easy to post files. These four were taken between 8:30 and 10am. The osprey shots were taken at f/8, 1/2000s and iso 800 and 2500. The lack of acuity is due to severe cropping rather than inadequate light. The other two shots were taken at f/7.1, 1/1600s, iso 800.

I'm not a big fan of auto ISO especially with cameras that are essentially ISO invariant above ISO 400 or 640. Thus, unless I totally blow the shot, it is easily correct in post. My experience with auto ISO is that it tends to raise the ISO too much. Of course, I could cap auto ISO at 1/3200, but I'm satisfied with my workflow.

Again, I have no problem keeping my shots (much) below ISO 3200 even at f/7.1 and f/8.0. I have a good idea what ISO is appropriate for light conditions, so I rarely have to raise exposure more than 1 stop in post.
I too use manual for iso invariant regions, especially for birds in flight, erring on the side of under-exposure. It's especially important when the background lighting changes as the bird flies across it. It's easy to guess the exposure from experience or using the sunny 16 rule, and pushing through a couple of stops is the same as upping the iso by a couple.
 
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PhotonShark

I'm New Here
Jun 10, 2020
11
11
Here's a super useful online exposure calculator.

Some example to get the equivalent exposure while retaining a given shutter speed.

f/5.6 at ISO 100 = f/6.3 at ISO 125 (133 rounded down)
f/5.6 at ISO 800 = f/6.3 at ISO 1000 (1066 rounded down)
f/5.6 at ISO 3200 = f/6.3 at ISO 4000 (4267 rounded down)

Exposure Calculator

Note : Values edited due to my error. Thanks AlanF for the unrounded and more accurate figures.
 
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AlanF

Stay alert, control the camera, save photos
Aug 16, 2012
6,832
5,872
Here's a super useful online exposure calculator.

Some example to get the equivalent exposure while retaining a given shutter speed.

f/5.6 at ISO 100 = f/6.3 at ISO 160
f/5.6 at ISO 800 = f/6.3 at ISO 1000
f/5.6 at ISO 3200 = f/6.3 at ISO 5000

Exposure Calculator
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.
 
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PhotonShark

I'm New Here
Jun 10, 2020
11
11
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.
My apologies, looks like I used the calculator incorrectly. I will edit my post. You can see the calculator shows rounded/nearest ISO values.
 
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Eclipsed

EOS M6 Mark II
Apr 30, 2020
98
87
I'm pre-ordered, and indifferent to the minor differences in aperture between the generations.

BUT, this is irritating. The reality is that a mechanical zoom lens with variable aperture will have a continuous function of aperture versus focal length, without steps. It will be f5.6 at only one focal length, faster at shorter, and narrower at longer. CANON, TELL ME WHAT THOSE NUMBERS ARE. It would be deceptive marketing to pretend that this is f5.6 at anything above the actual focal length at which it is 5.6. The fact that the display shows 5.6 does NOT mean it is "at" 5.6 at all those lengths. It might mean "at least 5.6" but I suspect not. I hope it doesn't mean "5.6 or less, but not as bad as 6.3".

I also fear that in the above example showing f5.6 from 254-363mm, we may be experiencing some anti-consumer deceptive rounding. I may be wrong, and would welcome being proven wrong, but if it's optically at 5.6 at 254, and f7.1 at the 363 transition point, this is unethical beyond rounding.

I also think it's unethical to sell a 383mm lens as 400.
 

bbasiaga

Canon Shooter
Nov 15, 2011
249
141
USA
marketing strikes again! but its not just canon, its everyone. And its not just this lens, its every one you've ever bought.

-Brian
 

BeenThere

EOS R
Sep 4, 2012
1,086
502
I'm pre-ordered, and indifferent to the minor differences in aperture between the generations.

BUT, this is irritating. The reality is that a mechanical zoom lens with variable aperture will have a continuous function of aperture versus focal length, without steps. It will be f5.6 at only one focal length, faster at shorter, and narrower at longer. CANON, TELL ME WHAT THOSE NUMBERS ARE. It would be deceptive marketing to pretend that this is f5.6 at anything above the actual focal length at which it is 5.6. The fact that the display shows 5.6 does NOT mean it is "at" 5.6 at all those lengths. It might mean "at least 5.6" but I suspect not. I hope it doesn't mean "5.6 or less, but not as bad as 6.3".

I also fear that in the above example showing f5.6 from 254-363mm, we may be experiencing some anti-consumer deceptive rounding. I may be wrong, and would welcome being proven wrong, but if it's optically at 5.6 at 254, and f7.1 at the 363 transition point, this is unethical beyond rounding.

I also think it's unethical to sell a 383mm lens as 400.
I think it’s industry practice to round off the numbers you are quoting. Have you ever seen a 383mm lens for sale? If it becomes too egregious, then the company reputation takes a hit, and reputation means a lot to the major manufacturers.
 

Eclipsed

EOS M6 Mark II
Apr 30, 2020
98
87
For those of us who are interested, it's not nitpicking but a desire to understand how our gear works and how to squeeze the best out of it. You don't have to understand much at all to get good images out of a camera or create works of art, but the technology is of great interest as well if you have a scientific bent.
Nor is it nitpicking when lenses that are a stop faster are double* the cost/value, and a 10%* shortfall in speed from what is marketed is real value.

*Examples for illustration.
 

Jack Douglas

CR for the Humour
Apr 10, 2013
6,609
1,967
Alberta, Canada
I'm pre-ordered, and indifferent to the minor differences in aperture between the generations.

BUT, this is irritating. The reality is that a mechanical zoom lens with variable aperture will have a continuous function of aperture versus focal length, without steps. It will be f5.6 at only one focal length, faster at shorter, and narrower at longer. CANON, TELL ME WHAT THOSE NUMBERS ARE. It would be deceptive marketing to pretend that this is f5.6 at anything above the actual focal length at which it is 5.6. The fact that the display shows 5.6 does NOT mean it is "at" 5.6 at all those lengths. It might mean "at least 5.6" but I suspect not. I hope it doesn't mean "5.6 or less, but not as bad as 6.3".

I also fear that in the above example showing f5.6 from 254-363mm, we may be experiencing some anti-consumer deceptive rounding. I may be wrong, and would welcome being proven wrong, but if it's optically at 5.6 at 254, and f7.1 at the 363 transition point, this is unethical beyond rounding.

I also think it's unethical to sell a 383mm lens as 400.
383 - Perhaps, but looking around this world we live in I think there are infinitely more unethical things going on constantly that we live with, sadly. ;)
 

AlanF

Stay alert, control the camera, save photos
Aug 16, 2012
6,832
5,872
Nor is it nitpicking when lenses that are a stop faster are double* the cost/value, and a 10%* shortfall in speed from what is marketed is real value.

*Examples for illustration.
The manufacturers are allowed a certain tolerance in defining the focal length and f-numbers of lenses. I once measured the front element of the 400mm f/4.O DO II to be about 95mm, and at least 100mm is needed for f/4. DxOMark measures its transmission to be equivalent to f/5.
 
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sobrien

I'm New Here
Apr 26, 2020
22
37
I'm pre-ordered, and indifferent to the minor differences in aperture between the generations.

BUT, this is irritating. The reality is that a mechanical zoom lens with variable aperture will have a continuous function of aperture versus focal length, without steps. It will be f5.6 at only one focal length, faster at shorter, and narrower at longer. CANON, TELL ME WHAT THOSE NUMBERS ARE. It would be deceptive marketing to pretend that this is f5.6 at anything above the actual focal length at which it is 5.6. The fact that the display shows 5.6 does NOT mean it is "at" 5.6 at all those lengths. It might mean "at least 5.6" but I suspect not. I hope it doesn't mean "5.6 or less, but not as bad as 6.3".

I also fear that in the above example showing f5.6 from 254-363mm, we may be experiencing some anti-consumer deceptive rounding. I may be wrong, and would welcome being proven wrong, but if it's optically at 5.6 at 254, and f7.1 at the 363 transition point, this is unethical beyond rounding.

I also think it's unethical to sell a 383mm lens as 400.
I don’t think variable aperture values are deceptive. There are swings and roundabouts. So, when an aperture value first changes that should mean that the actual aperture is wider than the value displayed - the value just happens to be the most proximate value. This is precisely what seems to be happening with the RF 100-500 - when it first moves to f/6.3 the reality is that it is f/6 or whatever at that point. Heck, given how little of this zoom range is at f/7.1 I wonder does it even reach f/7.1? Maybe Canon has undersold this lens?! :unsure:

The opposite is also true, though...as you get closer to the point where the value is about to increase the actual aperture is going to be higher than the value displayed. Some f/5.6 lenses might have a smaller aperture than f/5.6 but at least you know they will be closer to f/5.6 than f/6.3.

At least that’s how I understand these things to work.
 

tron

EOS R5
Nov 8, 2011
4,547
773
The manufacturers are allowed a certain tolerance in defining the focal length and f-numbers of lenses. I once measured the front element of the 400mm f/4.O DO II to be about 95mm, and at least 100mm is needed for f/4. DxOMark measures its transmission to be equivalent to f/5.
I remember hearing about the less than real focal length tactic for lenses many decades ago but of course they would include f-numbers too.
 
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