Here is the Canon RF 100-400mm f/5.6-8 IS USM

neuroanatomist

I post too Much on Here!!
CR Pro
Jul 21, 2010
25,791
4,190
Let's review. JohnOnTheNet said:



I replied that this was not correct because:



Neither one of us said anything about DOF, noise, or "equivalence". The statements were only about the lens being "brighter", i.e, providing greater luminous flux density, when used with one sensor versus another. But the properties of the lens do not change because there is a different size sensor behind it. the amount of light per unit area reaching the sensor is the same (assuming the lens can illuminate the full sensor).

In the context of the original statement, my response was correct and I feel no need to defend it further. Personal attacks on me, @neuroanatomist, won't change that.
Oh, so you’re going to be literal. That’s fine. The EF 100-400 f/5.6 is brighter than the RF 100-400 f/8 because the former is painted white and the latter is painted black. Brightness is emission or reflection of light, and the maximum aperture of the iris diaphragm inside the lens changes neither. Paint color affects brightness. I suppose you could also put a light bulb inside a lens to make it ‘brighter’. Likewise, an f/8 lens can be faster than an f/5.6 lens if the former is being transported by jet plane and the latter is being carried by someone walking on a trail.

Now that we have silliness out of the way, it’s pretty obvious that the original comment was in reference to equivalence, since it’s unlikely that someone would be silly enough to suggest that f/8 transmits more light than f/5.6. (Note that I mean relatively more light, since the f/number is a ratio it’s quite possible for an f/8 lens to transmit more absolute light through the iris diaphragm than an f/5.6 lens, if the latter has a sufficiently shorter focal length.)

You just decided to take an unrealistically narrow and silly approach to interpreting the original statement. I did so intentionally above, and I trust you see how ridiculous that approach comes off.

Still, I apologize for my harsh response. But honestly, claiming that total light gathered is meaningless for photography is about as asinine as saying a lens is fast because it’s being transported in a jet.
 

unfocused

EOS-1D X Mark III
Jul 20, 2010
6,310
3,853
68
Springfield, IL
www.mgordoncommunications.com
Let's review. JohnOnTheNet said:



I replied that this was not correct because:



Neither one of us said anything about DOF, noise, or "equivalence". The statements were only about the lens being "brighter", i.e, providing greater luminous flux density, when used with one sensor versus another. But the properties of the lens do not change because there is a different size sensor behind it. the amount of light per unit area reaching the sensor is the same (assuming the lens can illuminate the full sensor).

In the context of the original statement, my response was correct and I feel no need to defend it further. Personal attacks on me, @neuroanatomist, won't change that.
You are absolutely right, but don’t expect the equivalence gang on this forum to ever admit it. This argument crops up every few weeks and when you prove them wrong they just move the goal posts, claim they said something they didn’t say, twist themselves into pretzels and finally resort to insults. Best to just walk away because their egos are too tender to admit they are wrong.
 

stevelee

FT-QL
CR Pro
Jul 6, 2017
2,151
854
Davidson, NC
After reading pages and pages on equivalence, I concluded there is no such thing.

The best you can do is “equivalent in what way” or “equivalent for what purpose.”

For example, I decided to get a prime lens for my T3i for portraits. I liked 85mm on my film camera, so the question became what it was about that focal length on full frame that made it good for portraits. After some reading, I decided that subject distance was the key. So I bought a 50mm lens as the closest “equivalent” for my purpose. But I knew that putting it on the T3i was not going to change it optically to 85mm magically.
 

neuroanatomist

I post too Much on Here!!
CR Pro
Jul 21, 2010
25,791
4,190
After reading pages and pages on equivalence, I concluded there is no such thing.

The best you can do is “equivalent in what way” or “equivalent for what purpose.”
In the context of photography, the term equivalence has a specific definition. Yes, in the sense of a word in the English language, equivalence and equivalent are different parts of speech referring to the same basic definition. But photography has a technical aspect to it, and technical terms like equivalence have a meaning in that context.

As another example, when one photographer says to another, “You might want to add an extra stop,” the recipient of that advice knows it’s not a suggestion to program a favorite pub into the Google maps route home (of course, the latter might be good advice, too).
 
  • Like
Reactions: aceflibble

degos

EOS RP
Mar 20, 2015
421
356
Still, I apologize for my harsh response. But honestly, claiming that total light gathered is meaningless for photography is about as asinine as saying a lens is fast because it’s being transported in a jet.

Is contend that total captured light is irrelevant because ISO amplification works on the pixel i.e. photosite level.

So the key factor is received flux at each photosite, which is independent from how many photosites exist.
 
  • Like
Reactions: mdcmdcmdc

neuroanatomist

I post too Much on Here!!
CR Pro
Jul 21, 2010
25,791
4,190
Is contend that total captured light is irrelevant because ISO amplification works on the pixel i.e. photosite level.

So the key factor is received flux at each photosite, which is independent from how many photosites exist.
So you’re saying that the noise in an image at a given ISO is identical, independent of sensor size? ISO 1600 on a MF, FF, APS-C, 1/1.8” PowerShot and iPhone will have the same noise level in the resulting images?

I wonder why anyone would ever bother using a larger sensor?

Sure, total light gathered doesn’t matter. :rolleyes:
 

stevelee

FT-QL
CR Pro
Jul 6, 2017
2,151
854
Davidson, NC
In the context of photography, the term equivalence has a specific definition. Yes, in the sense of a word in the English language, equivalence and equivalent are different parts of speech referring to the same basic definition. But photography has a technical aspect to it, and technical terms like equivalence have a meaning in that context.
In normal parlance, we use it just to mean equivalent angle of view, as in my example where the 50mm on the T31 was “equivalent” to 80mm on FF. That’s the way I normally use it. For us old guys who used to shoot 35mm film, that helps us get our bearings.

But in discussions here, meanings are all over the map. The online pages on the topic go on and on and on. Sure there is a scientific basis for all these things. Exposures are compared such that f/8 is not equivalent to f/8, but maybe f/13.63 or something.

And even equivalent angle of view becomes swampy when you talk about 3:2 FF and crop, 4:3 Fuji medium format, and 16:9 video.
 

AlanF

Stay at home
CR Pro
Aug 16, 2012
8,672
11,655
In normal parlance, we use it just to mean equivalent angle of view, as in my example where the 50mm on the T31 was “equivalent” to 80mm on FF. That’s the way I normally use it. For us old guys who used to shoot 35mm film, that helps us get our bearings.

But in discussions here, meanings are all over the map. The online pages on the topic go on and on and on. Sure there is a scientific basis for all these things. Exposures are compared such that f/8 is not equivalent to f/8, but maybe f/13.63 or something.

And even equivalent angle of view becomes swampy when you talk about 3:2 FF and crop, 4:3 Fuji medium format, and 16:9 video.
I did a quick Google and found this article that describes nicely what is the general meaning of equivalence and why it applies to more than just field of view. It's worth a read.
 

neuroanatomist

I post too Much on Here!!
CR Pro
Jul 21, 2010
25,791
4,190
In normal parlance, we use it just to mean equivalent angle of view, as in my example where the 50mm on the T31 was “equivalent” to 80mm on FF. That’s the way I normally use it. For us old guys who used to shoot 35mm film, that helps us get our bearings.

But in discussions here, meanings are all over the map. The online pages on the topic go on and on and on. Sure there is a scientific basis for all these things. Exposures are compared such that f/8 is not equivalent to f/8, but maybe f/13.63 or something.

And even equivalent angle of view becomes swampy when you talk about 3:2 FF and crop, 4:3 Fuji medium format, and 16:9 video.
I get that. My point is that calling things equivalent is not the same as the defined concept of equivalence.

In normal parlance, ‘psychotic’ is used to mean ‘crazy’, but in medical terminology it has a specific meaning, and can be distinguished from other forms of mental illness in defined ways including semantic vs. syntactic language disturbances. The same is true in most fields. Terminology matters.

A good primer on photographic equivalence is here:
 

mdcmdcmdc

7Dii, M5, 100 (film), α6400
CR Pro
Sep 4, 2020
124
161
I get that. My point is that calling things equivalent is not the same as the defined concept of equivalence.

In normal parlance, ‘psychotic’ is used to mean ‘crazy’, but in medical terminology it has a specific meaning, and can be distinguished from other forms of mental illness in defined ways including semantic vs. syntactic language disturbances. The same is true in most fields. Terminology matters.

A good primer on photographic equivalence is here:
Neither JohnOnTheNet nor I mentioned photographic "equivalence", either in his original post or in my response to it. It is true that I used the word "equivalent" in my response, but I think it was pretty clear that I was referring to equivalence between statements.

While it is certainly possible that the original posting about the lens being "brighter" could have referred to the barrel's paint color, as neuroanatomist suggested, I have never heard "bright" used to describe either DOF or sensor noise.

In his original post, JohnOnTheNet did not say that f/8 on FF was "equivalent" to f/5.6 on crop. He said it was "brighter". In his followup post (#194) he clarified that he was talking about the amount of light on the sensor. It's right there in the second sentence.

It is disingenuous to use my original response to hijack this thread into an unrelated direction under the banner of "equivalence", and then cry foul and claim I am being "literal" when you get called out for your BS.
 

neuroanatomist

I post too Much on Here!!
CR Pro
Jul 21, 2010
25,791
4,190
Neither JohnOnTheNet nor I mentioned photographic "equivalence", either in his original post or in my response to it. It is true that I used the word "equivalent" in my response, but I think it was pretty clear that I was referring to equivalence between statements.

While it is certainly possible that the original posting about the lens being "brighter" could have referred to the barrel's paint color, as neuroanatomist suggested, I have never heard "bright" used to describe either DOF or sensor noise.

In his original post, JohnOnTheNet did not say that f/8 on FF was "equivalent" to f/5.6 on crop. He said it was "brighter". In his followup post (#194) he clarified that he was talking about the amount of light on the sensor. It's right there in the second sentence.

It is disingenuous to use my original response to hijack this thread into an unrelated direction under the banner of "equivalence", and then cry foul and claim I am being "literal" when you get called out for your BS.
He didn’t need to use the word equivalence. When he mentioned sensor sizes, it was implied. When he clarified in post #194, it became manifestly obvious that was his context:

The point being that aperture is a ratio, not a size. Canon APSC is less than half the area of full frame, so one stop smaller aperture on full frame allows more than twice the light onto the sensor and consequently halves the effective ISO (noise.)
He specifically mentions that his use of ‘brighter’ meant more total light falling on the sensor, which results in less image noise.

The only BS here is your inability to admit that you misinterpreted his original point. He said nothing about exposure, you just assumed that’s what he meant. You were wrong.
 
  • Haha
Reactions: mdcmdcmdc

neuroanatomist

I post too Much on Here!!
CR Pro
Jul 21, 2010
25,791
4,190
As I said, I’ve read all that stuff. I stand by my conclusions from it.
That’s your prerogative. Fortunately, standing by your conclusion is harmless. I wish that could be said for the anti-vaccine crowd standing by theirs (as those around them succumb and/or they treat themselves with horse dewormer).
 

stevelee

FT-QL
CR Pro
Jul 6, 2017
2,151
854
Davidson, NC
That’s your prerogative. Fortunately, standing by your conclusion is harmless. I wish that could be said for the anti-vaccine crowd standing by theirs (as those around them succumb and/or they treat themselves with horse dewormer).
I realize all that other stuff. I just find it irrelevant for any practical purposes of mine. Total light on the sensor can be of interest in a technical discussion, but I’m not using it to set my exposure. No matter how you set everything, a 50mm lens is not going to become an 80mm lens. So, yes, my opinion is harmless to me and everybody else. It is not like I’m asking people to sacrifice their children or anything.
 

Czardoom

EOS RP
Jan 27, 2020
315
692
So you’re saying that the noise in an image at a given ISO is identical, independent of sensor size? ISO 1600 on a MF, FF, APS-C, 1/1.8” PowerShot and iPhone will have the same noise level in the resulting images?

I wonder why anyone would ever bother using a larger sensor?

Sure, total light gathered doesn’t matter. :rolleyes:
The Clarkvision website goes into a great deal of detail as to what the main factor is in producing "noise." He demonstrates that it is possible to have the same amount of noise in images from different size sensors. The most important determining factor is the size of the lens opening - not the f-stop, not the sensor size. I think this is where the confusion starts. F/8 is f/8 when it comes to the exposure of the photo with different size sensors, but the size of the lens opening is NOT the same. The lens set to f/8 on the camera with the larger sensor will have a larger lens opening than a crop sensor camera set to f/8. Or as Neuro has pointed out, it gathers more light. To equalize the amount of light with a smaller sensor, one would need to use a considerably smaller number f-stop (often an f-number smaller than the lens is capable of) and/or a considerably longer exposure time.

From Clarkvision's website (when he says "smaller camera" and "larger camera" he is describing the size of the sensor):

"But constant f-ratio is NOT the same amount of light. This is a common misunderstanding of f-ratios. Constant f-ratio means constant light density in the focal plane (e.g. photons [per square micron). With constant f-ratio, as focal length increases, the lens aperture diameter increases and the lens collects MORE light from the subject This means the smaller camera had a smaller lens that collected less total light than the larger camera, as the both used the same f-ratio.

In this series of comparisons, I'll describe the true reasons for the differences in noise. The true differences in apparent noise are due to the amount of light collected by each camera. The common internet cited reason for the larger sensor camera is that the sensor is responsible. No, it is the lens. The sensor is just a receptacle to hold the photoelectrons."
 
Last edited:
  • Like
Reactions: mdcmdcmdc

Czardoom

EOS RP
Jan 27, 2020
315
692
I realize all that other stuff. I just find it irrelevant for any practical purposes of mine. Total light on the sensor can be of interest in a technical discussion, but I’m not using it to set my exposure. No matter how you set everything, a 50mm lens is not going to become an 80mm lens. So, yes, my opinion is harmless to me and everybody else. It is not like I’m asking people to sacrifice their children or anything.
Despite my post above, I find all the talk of equivalence and noise to be mostly irrelevant also. You cannot go onto a M4/3rds forum, for example, and say anything positive about a M4/3rds camera or lens with the equivalence police chastising you for your stupidity for not realizing how inferior your M4/3rds products are due to the increased noise. Since I am not a pixel peeper and do not shoot nightime scenes at concerts or other dimly lit locations, the amount of noise on my crop cameras is not an issue. I just know that I can set my FF Nikon to shoot maximum ISO of 12800 or even 25600, and my crop Olympus camera is set to maximum ISO to 3200 or 6400. And then I can forget all about equivalence!
 

neuroanatomist

I post too Much on Here!!
CR Pro
Jul 21, 2010
25,791
4,190
I just find it irrelevant for any practical purposes of mine. Total light on the sensor can be of interest in a technical discussion, but I’m not using it to set my exposure.
You’re right, there’s not much practical relevance. If you’re holding a camera and taking a picture, why would you care what would happen if your camera had a different size sensor. Ok, so there’s crop mode on some cameras, but why would you want to make a full and crop mode picture look the same?

On the other hand, when someone makes a statement that is wrong, that statement should be refuted by factual information. The appropriate response to someone claiming that vaccines don’t work is evidence that they do, and the appropriate response to someone claiming that total light gathered is meaningless for photography is an explanation that involves equivalence.
 
  • Like
Reactions: slclick

neuroanatomist

I post too Much on Here!!
CR Pro
Jul 21, 2010
25,791
4,190
Despite my post above, I find all the talk of equivalence and noise to be mostly irrelevant also. You cannot go onto a M4/3rds forum, for example, and say anything positive about a M4/3rds camera or lens with the equivalence police chastising you for your stupidity for not realizing how inferior your M4/3rds products are due to the increased noise. Since I am not a pixel peeper and do not shoot nightime scenes at concerts or other dimly lit locations, the amount of noise on my crop cameras is not an issue. I just know that I can set my FF Nikon to shoot maximum ISO of 12800 or even 25600, and my crop Olympus camera is set to maximum ISO to 3200 or 6400. And then I can forget all about equivalence!
Good approach. That’s the practical application, and similarly I use a lower ISO ‘cap’ for my APS-C cameras.

FF cameras offer more exposure-related choices than APS-C, which in turn offer more exposure-related choices than m4/3. Those are facts. But that doesn’t mean m4/3 are inferior, they’re just offering different compromises. I’ve run across some who tout the superiority of FF over APS-C or m4/3, and have on occasion thrown their reasons back at them as to why they don’t shoot medium format instead of FF…then I get to watch them flounder as they try to explain how the compromises they chose are somehow better than the compromises chosen by those shooting with APS-C or m4/3.

The best camera is the one in your hands.
 
  • Like
Reactions: scyrene

stevelee

FT-QL
CR Pro
Jul 6, 2017
2,151
854
Davidson, NC
Good approach. That’s the practical application, and similarly I use a lower ISO ‘cap’ for my APS-C cameras.

FF cameras offer more exposure-related choices than APS-C, which in turn offer more exposure-related choices than m4/3. Those are facts. But that doesn’t mean m4/3 are inferior, they’re just offering different compromises. I’ve run across some who tout the superiority of FF over APS-C or m4/3, and have on occasion thrown their reasons back at them as to why they don’t shoot medium format instead of FF…then I get to watch them flounder as they try to explain how the compromises they chose are somehow better than the compromises chosen by those shooting with APS-C or m4/3.

The best camera is the one in your hands.
I don’t have much occasion to use my T3i any more, so I am shooting either FF or so-called 1” sensor. (And currently not traveling, I don’t use the 1”, either.) Whatever the theory, I know the practical ISO limits for my cameras from experience. There are cameras in each class that have better or worse responses at those settings, so it is not 100% a matter of theory. If I go outside those limits, I do it as a compromise with other settings. And I have already decided that for me, medium format is the step to take if I ever decide to spend over $4,000 on another camera body. So far I am not convinced that it would make enough difference for what I do or change what I shoot enough if I had better equipment.
 

AlanF

Stay at home
CR Pro
Aug 16, 2012
8,672
11,655
I don’t have much occasion to use my T3i any more, so I am shooting either FF or so-called 1” sensor. (And currently not traveling, I don’t use the 1”, either.) Whatever the theory, I know the practical ISO limits for my cameras from experience. There are cameras in each class that have better or worse responses at those settings, so it is not 100% a matter of theory. If I go outside those limits, I do it as a compromise with other settings. And I have already decided that for me, medium format is the step to take if I ever decide to spend over $4,000 on another camera body. So far I am not convinced that it would make enough difference for what I do or change what I shoot enough if I had better equipment.
Very true, we learn from experience what we can do with our equipment, and I always take serious notice of people (whom I trust) who speak from first hand practical experience. And you can learn successfully without any knowledge of theory. We can also use theory to learn from. For example, a 400mm f/5.6, a 500mm f/7.1 and an 800mm f/11 have the same entrance pupil (effective diameter of the front element in practice of 71-72mm). If you take a photo of a duck from the same distance, all three lenses spread the same number of photons over the duck, and the all produce the same signal/noise in the image of the duck, despite the difference in f-numbers. So, you can increase the iso with the narrower lenses to compensate for the reduced apertures without making the images noisier when light is limiting. Those who have used these lenses know from experience that you can use higher iso with the f/11 lenses successfully as do those who don't have the lenses but know they are equivalent. Unfortunately, there are those who have neither used them nor know the theory and write them off as being unusable drinking straw lenses. It's the lack of first hand experience combined with the lack of theoretical knowledge that leads to many of the repeated myths that need to be answered.