Rethinking focal length conventions

Started 9 months ago | Discussions
Phil A Martin
Phil A Martin Veteran Member • Posts: 6,774
Re: 6%
  1. Pixel Pooper wrote:

Phil A Martin wrote:

Pixel Pooper wrote:

My point is that a 43mm lens does not match the perspective of the human eye, it matches the perspective of an image viewed from a distance equal to the image diagonal. If you view your images from closer it might be 28mm that matches the perspective, and from a bit farther it might be 65mm. There is nothing special about 43mm except that it matches what was once considered "standard" viewing conditions.

So basically you are saying that the conventions of decades are wrong and that there is no such thing as a standard lens.

No, I'm saying that you, and many others misunderstood

Such arrogance. I have misunderstood nothing and also perfectly understand your games.

the conventions of decades and the meaning of a standard lens. A standard, or normal lens is one that produces a natural looking perspective under standard viewing conditions,

As I've been saying

which is when an image is viewed at a distance equal to its diagonal measurement.

No because the effect is also seen when you look through the camera viewfinder.

These are the same viewing conditions used by DOF calculators and in both cases the results are only correct when the viewing conditions are met.

No, what you are doing is engaging in a ridiculous point scoring exercises, when you know perfectly well what people mean by a standard lens and for full frame, the 43mm lens is the ideal choice.

Phil A Martin
Phil A Martin Veteran Member • Posts: 6,774
Re: 6%

Paul Pasco wrote:

Phil A Martin wrote:

Gerry Winterbourne wrote:

Phil A Martin wrote:

jrtrent wrote:

tko wrote:

You're thinking you need a 40 mm instead of 35 mm? Of what importance is this? How did you get this conclusion? How would a 85/80 = 6% difference in FL rock your world? I don't get this at all. It would seem like you think your numbers are better since they are "more rounded off," and you want lens manufacturers to come up with new products where the focal lengths are "prettier."

You may be right about the difference between 80 and 85 mm, but apparently there's a noticeable difference around 40mm:

"40mm is the "Perfect Normal" focal length for full-frame. Unlike 50mm lenses which often are too long or 35mm lenses which are often too wide, 40mm is always just right."

And that's from Ken Rockwell himself!

He's wrong, it's 43mm is actually the perfect focal length for full frame. It corresponds to the sensor diagonal of 43.27mm.

There is no single "perfect" focal length. Human eyes vary in size; if "perfection" means matching human vision then it varies depending on the individual. 43mm was picked out of the range of visually "normal" focal lengths because it corresponds to the diagonal of 135 format - an arbitrary choice that doesn't confer perfection.

It is the focal length of the "true" standard lens, where perspective is seen as the human eye sees it. This has been an acknowledged truth throughout the history of photography and is easily demonstrated in practice.

My observation going back to the 70’s was that when you put a 50mm or so lens on a DSLR and looked through viewfinder with both eyes open, the size of objects appeared very close to the same

And this is the important point, not the angle of view. With a 43mm lens, the sizes would appear even closer.

but that totally discounts how much the eye takes in from the periphery that is cut off by the viewfinder boundaries. So, the eye actually has a much wider field of view than that of a 50mm lens in a FF camera. The eye/brain “system” is based on a sphere and behaves very differently than a lens and a flat focal plane.

I'm not saying this is wrong but I don't see it's relevance? What we are doing when we are taking photographs, is framing small sections of what we see in front of us and turning it into 2D images.

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Gerry
________________________________________________________________________
I'm happy for anyone to edit any of my photos and display the results
_________________________________________________________________________
First camera 1953, first Pentax 1985, first DSLR 2006
http://www.pbase.com/gerrywinterbourne
gerry.winterbourne@ntlworld.com

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Regards, Paul
Lili's Dad
WSSA Member #450

Phil A Martin
Phil A Martin Veteran Member • Posts: 6,774
Re: 6%

J A C S wrote:

Pixel Pooper wrote:

Phil A Martin wrote:

Pixel Pooper wrote:

My point is that a 43mm lens does not match the perspective of the human eye, it matches the perspective of an image viewed from a distance equal to the image diagonal. If you view your images from closer it might be 28mm that matches the perspective, and from a bit farther it might be 65mm. There is nothing special about 43mm except that it matches what was once considered "standard" viewing conditions.

So basically you are saying that the conventions of decades are wrong and that there is no such thing as a standard lens.

No, I'm saying that you, and many others misunderstood the conventions of decades and the meaning of a standard lens. A standard, or normal lens is one that produces a natural looking perspective under standard viewing conditions, which is when an image is viewed at a distance equal to its diagonal measurement. These are the same viewing conditions used by DOF calculators and in both cases the results are only correct when the viewing conditions are met.

The only study I have seen finds that the standard viewing distance corresponds to a considerable longer FL than the diagonal. Also, it depends on the size, i.e., it is not even proportional to the diagonal, it is something like 1.3 x diagonal + 25.3 cm. For larger prints, "normal" is 55-60cm. Nobody looks at their phone at 5 inches or so, BTW.

Agreed.

Phil A Martin
Phil A Martin Veteran Member • Posts: 6,774
Re: 6%

J A C S wrote:

Phil A Martin wrote:

jrtrent wrote:

tko wrote:

You're thinking you need a 40 mm instead of 35 mm? Of what importance is this? How did you get this conclusion? How would a 85/80 = 6% difference in FL rock your world? I don't get this at all. It would seem like you think your numbers are better since they are "more rounded off," and you want lens manufacturers to come up with new products where the focal lengths are "prettier."

You may be right about the difference between 80 and 85 mm, but apparently there's a noticeable difference around 40mm:

"40mm is the "Perfect Normal" focal length for full-frame. Unlike 50mm lenses which often are too long or 35mm lenses which are often too wide, 40mm is always just right."

And that's from Ken Rockwell himself!

He's wrong, it's 43mm is actually the perfect focal length for full frame. It corresponds to the sensor diagonal of 43.27mm.

You are both wrong. There is no such thing as a perfect FL. It is a superstition.

If you want to play word games, then fine. Enjoy yourself.

I only used the phrase "perfect" because Rockwell used it and I was replying to his quoted comment and not that I thought the 43mm focal length to be perfect focal length under all situations and circumstances.

Maybe I should have been clearer and said that 43mm is the ideal focal length for a standard lens that renders natural perspective on a 35mm or Full Frame camera?

Pixel Pooper Veteran Member • Posts: 3,958
Re: 6%
3

Phil A Martin wrote:

  1. Pixel Pooper wrote:

Phil A Martin wrote:

Pixel Pooper wrote:

My point is that a 43mm lens does not match the perspective of the human eye, it matches the perspective of an image viewed from a distance equal to the image diagonal. If you view your images from closer it might be 28mm that matches the perspective, and from a bit farther it might be 65mm. There is nothing special about 43mm except that it matches what was once considered "standard" viewing conditions.

So basically you are saying that the conventions of decades are wrong and that there is no such thing as a standard lens.

No, I'm saying that you, and many others misunderstood

Such arrogance. I have misunderstood nothing and also perfectly understand your games.

Your repeated claim that 43mm matches the perspective of the human eye suggests otherwise. Our perspective depends on where we stand when we look at something, it is not a property of the human eye.

the conventions of decades and the meaning of a standard lens. A standard, or normal lens is one that produces a natural looking perspective under standard viewing conditions,

As I've been saying

which is when an image is viewed at a distance equal to its diagonal measurement.

No because the effect is also seen when you look through the camera viewfinder.

That depends on the viewfinder. I have 4 cameras with viewfinders and they are all different.

These are the same viewing conditions used by DOF calculators and in both cases the results are only correct when the viewing conditions are met.

No, what you are doing is engaging in a ridiculous point scoring exercises, when you know perfectly well what people mean by a standard lens and for full frame, the 43mm lens is the ideal choice.

I do know perfectly well what people mean. I also know that they are mistaken.

Pixel Pooper Veteran Member • Posts: 3,958
Re: 6%
3

Phil A Martin wrote:

Paul Pasco wrote:

My observation going back to the 70’s was that when you put a 50mm or so lens on a DSLR and looked through viewfinder with both eyes open, the size of objects appeared very close to the same

And this is the important point, not the angle of view. With a 43mm lens, the sizes would appear even closer.

This depends on viewfinder magnification. On my 35mm SLR sizes look the same at 52mm, but on my A7III it is 65mm and on my RX100 it never happens because the lens isn't long enough.

Gerry Winterbourne Forum Pro • Posts: 19,062
Re: 6%
1

Phil A Martin wrote:

Gerry Winterbourne wrote:

Phil A Martin wrote:

Gerry Winterbourne wrote:

Phil A Martin wrote:

Gerry Winterbourne wrote:

Phil A Martin wrote:

jrtrent wrote:

tko wrote:

You're thinking you need a 40 mm instead of 35 mm? Of what importance is this? How did you get this conclusion? How would a 85/80 = 6% difference in FL rock your world? I don't get this at all. It would seem like you think your numbers are better since they are "more rounded off," and you want lens manufacturers to come up with new products where the focal lengths are "prettier."

You may be right about the difference between 80 and 85 mm, but apparently there's a noticeable difference around 40mm:

"40mm is the "Perfect Normal" focal length for full-frame. Unlike 50mm lenses which often are too long or 35mm lenses which are often too wide, 40mm is always just right."

And that's from Ken Rockwell himself!

He's wrong, it's 43mm is actually the perfect focal length for full frame. It corresponds to the sensor diagonal of 43.27mm.

There is no single "perfect" focal length. Human eyes vary in size; if "perfection" means matching human vision then it varies depending on the individual. 43mm was picked out of the range of visually "normal" focal lengths because it corresponds to the diagonal of 135 format - an arbitrary choice that doesn't confer perfection.

It is the focal length of the "true" standard lens, where perspective is seen as the human eye sees it. This has been an acknowledged truth throughout the history of photography and is easily demonstrated in practice.

There is no such thing as "the" human eye.

There is, I can't have speak for you but I have two.

That is not "the" human eye; each is "a" human eye.

As I said (but you ignored) human eyes vary.

Which is irrelevant because I am clearly speaking about the average human eye.

It isn't irrelevant at all. You said it was perfect -

As explained elsewhere in this thread and something you should have realised had you followed it closely, I used the term "perfect" in response to the Ken Rockwell quote, where he claimed that the "40mm is the 'perfect normal focal length for full-frame" and that is all.

I did notice that but it's totally irrelevant to what I'm saying.

First, if someone wrongly claims that something is perfect, claiming equally wrongly that something different is perfect adds nothing.

It was not intended to insinuate that the 43mm focal length of full frame is the perfect lens for all occasions and circumstances.

Saying something is "perfect" without qualification means that whether you intended it or not. As I've said before, it makes life much easier for everyone if you say what you mean instead of leaving people to puzzle out your obscure meanings.

but it can only be perfect for a individual whose eyes are exactly the average (in which case 43mm wouldn't be perfect - 43.27mm would.

The history of photography started 100 years before a format with diagonal of 43mm came along:

When it is clear I'm talking about 35mm format/full frame but I'm sure you realised that.

Why would it be clear from the term "throughout the history of photography" that you really meant only the second half of that history? Why don't you say what you mean instead of setting guessing games?

Obviously other formats will have standard lenses of different focal length. APS-C for example, the standard lens will be around 28mm.

show me a convincing demonstration that it is true for every human eye.

As explained above, this comment is irrelevant.

I assume that you would agree that wide angle lenses exaggerate perspective?

No, I won't. I'll agree that they exaggerate the perception of perspective.

Again pedantry. You know exactly what I meant yet choose disagreement for the sake of it.

No. There is a big difference between reality and perception. Many people here firmly believe that focal length changes actual perspective (and argue strongly for that). If you use the same language as them how am I (or anyone) to knbow that you mean something different?

(It is part of the basic ABC of photography after all) and as the focal length shortens, the angle of view increases and with it the exaggeration of perspective. Likewise with telephoto lenses, increasing the focal length narrows the angle of view and increasingly foreshortens perspective.

All of this depends on how the picture is viewed. If you can view the picture so that the angle it subtends at the eye is the same as the angle subtended by the lens on the sensor there is no appearance of distortion.

If you understand and agree with this basic photographic theory and there's no reason you shouldn't.

Well, I understand and agree with the basic theory; what I don't agree with is how you explain it.

Then you should agree that if we go through all the potential focal lengths for a given format, we will reach a point of cross over where the focal length neither exaggerates nor compresses the apparent perspective and that is what we call the standard lens. Which for 35mm/FF, will be in the 40-50mm range.

Well, other people extend that range but, yes, I'm happy with that. But that isn't demonstrating that 43mm specifically is the "perfect" focal length - which is what you started by claiming.

Because in the continuum of focal lengths, the focal length that marks the transition from wide to telephoto, corresponds to the length of the diagonal of the sensor. In this instance 43mm or thereabouts.

You keep saying that without any explanation: I keep asking you for an explanation, with no reply.

Obviously in custom and practice, the 50mm is usually cited as the standard lens but many fixed lens 35mm cameras of the 1950s to the 1980s, often had a lens in the 40-45mm range.

True - but that explains nothing.

The Pentax 43mm f/1.9 ltd being a good example of such a lens, because the focal length is almost identical to the negative/sensor diagonal of 43.27mm.

Why does matching the diagonal matter? What is special about it?

See above.

Assuming the sensor to be 24x36mm, as they are claimed to be.

Actually, they "claim" 35.9 x 24.0mm.

And this sums you up perfectly, pointless pedantry in the extreme.

It isn't pedantry - it's pointing out that you can't be bothered to check things before saying them.

That's it, I've had enough of your pedantic point scoring. Good night.

-- hide signature --

Gerry
________________________________________________________________________
I'm happy for anyone to edit any of my photos and display the results
_________________________________________________________________________
First camera 1953, first Pentax 1985, first DSLR 2006
http://www.pbase.com/gerrywinterbourne
gerry.winterbourne@ntlworld.com

Phil A Martin
Phil A Martin Veteran Member • Posts: 6,774
Re: 6%

Pixel Pooper wrote:

Phil A Martin wrote:

  1. Pixel Pooper wrote:

Phil A Martin wrote:

Pixel Pooper wrote:

My point is that a 43mm lens does not match the perspective of the human eye, it matches the perspective of an image viewed from a distance equal to the image diagonal. If you view your images from closer it might be 28mm that matches the perspective, and from a bit farther it might be 65mm. There is nothing special about 43mm except that it matches what was once considered "standard" viewing conditions.

So basically you are saying that the conventions of decades are wrong and that there is no such thing as a standard lens.

No, I'm saying that you, and many others misunderstood

Such arrogance. I have misunderstood nothing and also perfectly understand your games.

Your repeated claim that 43mm matches the perspective of the human eye suggests otherwise. Our perspective depends on where we stand when we look at something, it is not a property of the human

the conventions of decades and the meaning of a standard lens. A standard, or normal lens is one that produces a natural looking perspective under standard viewing conditions,

As I've been saying

which is when an image is viewed at a distance equal to its diagonal measurement.

No because the effect is also seen when you look through the camera viewfinder.

That depends on the viewfinder. I have 4 cameras with viewfinders and they are all different.

These are the same viewing conditions used by DOF calculators and in both cases the results are only correct when the viewing conditions are met.

No, what you are doing is engaging in a ridiculous point scoring exercises, when you know perfectly well what people mean by a standard lens and for full frame, the 43mm lens is the ideal choice.

I do know perfectly well what people mean. I also know that they are mistaken.

I refuse to engage with your word play and misquotes, you've had your fun. This conversation is over.

Pixel Pooper Veteran Member • Posts: 3,958
Re: 6%
1

Phil A Martin wrote:

I refuse to engage with your word play and misquotes, you've had your fun. This conversation is over.

Apology accepted 

Phil A Martin
Phil A Martin Veteran Member • Posts: 6,774
Re: 6%

Gerry Winterbourne wrote:

Phil A Martin wrote:

Gerry Winterbourne wrote:

Phil A Martin wrote:

Gerry Winterbourne wrote:

Phil A Martin wrote:

Gerry Winterbourne wrote:

Phil A Martin wrote:

jrtrent wrote:

tko wrote:

You're thinking you need a 40 mm instead of 35 mm? Of what importance is this? How did you get this conclusion? How would a 85/80 = 6% difference in FL rock your world? I don't get this at all. It would seem like you think your numbers are better since they are "more rounded off," and you want lens manufacturers to come up with new products where the focal lengths are "prettier."

You may be right about the difference between 80 and 85 mm, but apparently there's a noticeable difference around 40mm:

"40mm is the "Perfect Normal" focal length for full-frame. Unlike 50mm lenses which often are too long or 35mm lenses which are often too wide, 40mm is always just right."

And that's from Ken Rockwell himself!

He's wrong, it's 43mm is actually the perfect focal length for full frame. It corresponds to the sensor diagonal of 43.27mm.

There is no single "perfect" focal length. Human eyes vary in size; if "perfection" means matching human vision then it varies depending on the individual. 43mm was picked out of the range of visually "normal" focal lengths because it corresponds to the diagonal of 135 format - an arbitrary choice that doesn't confer perfection.

It is the focal length of the "true" standard lens, where perspective is seen as the human eye sees it. This has been an acknowledged truth throughout the history of photography and is easily demonstrated in practice.

There is no such thing as "the" human eye.

There is, I can't have speak for you but I have two.

That is not "the" human eye; each is "a" human eye.

As I said (but you ignored) human eyes vary.

Which is irrelevant because I am clearly speaking about the average human eye.

It isn't irrelevant at all. You said it was perfect -

As explained elsewhere in this thread and something you should have realised had you followed it closely, I used the term "perfect" in response to the Ken Rockwell quote, where he claimed that the "40mm is the 'perfect normal focal length for full-frame" and that is all.

I did notice that but it's totally irrelevant to what I'm saying.

First, if someone wrongly claims that something is perfect, claiming equally wrongly that something different is perfect adds nothing.

It was not intended to insinuate that the 43mm focal length of full frame is the perfect lens for all occasions and circumstances.

Saying something is "perfect" without qualification means that whether you intended it or not. As I've said before, it makes life much easier for everyone if you say what you mean instead of leaving people to puzzle out your obscure meanings.

No what you mean it would make life easier if I didn't leave gaps where pedants can sneak in to twist words out of context for ego stroking point scoring exercises.

but it can only be perfect for a individual whose eyes are exactly the average (in which case 43mm wouldn't be perfect - 43.27mm would.

The history of photography started 100 years before a format with diagonal of 43mm came along:

When it is clear I'm talking about 35mm format/full frame but I'm sure you realised that.

Why would it be clear from the term "throughout the history of photography" that you really meant only the second half of that history? Why don't you say what you mean instead of setting guessing games?

Obviously other formats will have standard lenses of different focal length. APS-C for example, the standard lens will be around 28mm.

show me a convincing demonstration that it is true for every human eye.

As explained above, this comment is irrelevant.

I assume that you would agree that wide angle lenses exaggerate perspective?

No, I won't. I'll agree that they exaggerate the perception of perspective.

Again pedantry. You know exactly what I meant yet choose disagreement for the sake of it.

No. There is a big difference between reality and perception. Many people here firmly believe that focal length changes actual perspective (and argue strongly for that). If you use the same language as them how am I (or anyone) to knbow that you mean something different?

(It is part of the basic ABC of photography after all) and as the focal length shortens, the angle of view increases and with it the exaggeration of perspective. Likewise with telephoto lenses, increasing the focal length narrows the angle of view and increasingly foreshortens perspective.

All of this depends on how the picture is viewed. If you can view the picture so that the angle it subtends at the eye is the same as the angle subtended by the lens on the sensor there is no appearance of distortion.

If you understand and agree with this basic photographic theory and there's no reason you shouldn't.

Well, I understand and agree with the basic theory; what I don't agree with is how you explain it.

Then you should agree that if we go through all the potential focal lengths for a given format, we will reach a point of cross over where the focal length neither exaggerates nor compresses the apparent perspective and that is what we call the standard lens. Which for 35mm/FF, will be in the 40-50mm range.

Well, other people extend that range but, yes, I'm happy with that. But that isn't demonstrating that 43mm specifically is the "perfect" focal length - which is what you started by claiming.

Because in the continuum of focal lengths, the focal length that marks the transition from wide to telephoto, corresponds to the length of the diagonal of the sensor. In this instance 43mm or thereabouts.

You keep saying that without any explanation: I keep asking you for an explanation, with no reply.

Obviously in custom and practice, the 50mm is usually cited as the standard lens but many fixed lens 35mm cameras of the 1950s to the 1980s, often had a lens in the 40-45mm range.

True - but that explains nothing.

The Pentax 43mm f/1.9 ltd being a good example of such a lens, because the focal length is almost identical to the negative/sensor diagonal of 43.27mm.

Why does matching the diagonal matter? What is special about it?

See above.

Assuming the sensor to be 24x36mm, as they are claimed to be.

Actually, they "claim" 35.9 x 24.0mm.

And this sums you up perfectly, pointless pedantry in the extreme.

It isn't pedantry - it's pointing out that you can't be bothered to check things before saying them.

That's it, I've had enough of your pedantic point scoring. Good night.

This conversation is over.

-- hide signature --

Gerry
________________________________________________________________________
I'm happy for anyone to edit any of my photos and display the results
_________________________________________________________________________
First camera 1953, first Pentax 1985, first DSLR 2006
http://www.pbase.com/gerrywinterbourne
gerry.winterbourne@ntlworld.com

Phil A Martin
Phil A Martin Veteran Member • Posts: 6,774
Re: 6%

Pixel Pooper wrote:

Phil A Martin wrote:

Paul Pasco wrote:

My observation going back to the 70’s was that when you put a 50mm or so lens on a DSLR and looked through viewfinder with both eyes open, the size of objects appeared very close to the same

And this is the important point, not the angle of view. With a 43mm lens, the sizes would appear even closer.

This depends on viewfinder magnification. On my 35mm SLR sizes look the same at 52mm, but on my A7III it is 65mm and on my RX100 it never happens because the lens isn't long enough.

Paul Pasco said "through viewfinder with both eyes open, the size of objects appeared very close to the same" and I replied "With a 43mm lens, the sizes would appear even closer". Neither of us said they would appear exactly the same through the viewfinder as with the naked eye.

Phil A Martin
Phil A Martin Veteran Member • Posts: 6,774
Re: 6%

Pixel Pooper wrote:

Phil A Martin wrote:

I refuse to engage with your word play and misquotes, you've had your fun. This conversation is over.

Apology accepted

Thank you for confirming what I suspected.

Pixel Pooper Veteran Member • Posts: 3,958
Re: 6%
1

Phil A Martin wrote:

Pixel Pooper wrote:

Phil A Martin wrote:

Paul Pasco wrote:

My observation going back to the 70’s was that when you put a 50mm or so lens on a DSLR and looked through viewfinder with both eyes open, the size of objects appeared very close to the same

And this is the important point, not the angle of view. With a 43mm lens, the sizes would appear even closer.

This depends on viewfinder magnification. On my 35mm SLR sizes look the same at 52mm, but on my A7III it is 65mm and on my RX100 it never happens because the lens isn't long enough.

Paul Pasco said "through viewfinder with both eyes open, the size of objects appeared very close to the same" and I replied "With a 43mm lens, the sizes would appear even closer". Neither of us said they would appear exactly the same through the viewfinder as with the naked eye.

At 43mm the sizes would not appear closer. With a viewfinder magnification of 1 they will be the same size at 50mm. Most cameras have a viewfinder magnification below 1 so the sizes will appear the same at a focal length longer than 50mm. For them to be the same at 43mm you would need a viewfinder magnification of 1.16 which is not available on any FF camera.

Phil A Martin
Phil A Martin Veteran Member • Posts: 6,774
Re: 6%

Pixel Pooper wrote:

Phil A Martin wrote:

Pixel Pooper wrote:

Phil A Martin wrote:

Paul Pasco wrote:

My observation going back to the 70’s was that when you put a 50mm or so lens on a DSLR and looked through viewfinder with both eyes open, the size of objects appeared very close to the same

And this is the important point, not the angle of view. With a 43mm lens, the sizes would appear even closer.

This depends on viewfinder magnification. On my 35mm SLR sizes look the same at 52mm, but on my A7III it is 65mm and on my RX100 it never happens because the lens isn't long enough.

Paul Pasco said "through viewfinder with both eyes open, the size of objects appeared very close to the same" and I replied "With a 43mm lens, the sizes would appear even closer". Neither of us said they would appear exactly the same through the viewfinder as with the naked eye.

At 43mm the sizes would not appear closer. With a viewfinder magnification of 1 they will be the same size at 50mm. Most cameras have a viewfinder magnification below 1 so the sizes will appear the same at a focal length longer than 50mm. For them to be the same at 43mm you would need a viewfinder magnification of 1.16 which is not available on any FF camera.

So now you have a better idea of what I can see through the viewfinder of my own camera with my own eyes than I do. How did you get this super power, a radioactive lens maybe?

This conversation is over. It's not going anywhere and I no longer wish to exchange pedantries with you. It's a 2aste of time. Goodbye.

jrtrent Veteran Member • Posts: 6,221
Re: 6%
3

Phil A Martin wrote:

Pixel Pooper wrote:

Phil A Martin wrote:

Pixel Pooper wrote:

Phil A Martin wrote:

Paul Pasco wrote:

My observation going back to the 70’s was that when you put a 50mm or so lens on a DSLR and looked through viewfinder with both eyes open, the size of objects appeared very close to the same

And this is the important point, not the angle of view. With a 43mm lens, the sizes would appear even closer.

This depends on viewfinder magnification. On my 35mm SLR sizes look the same at 52mm, but on my A7III it is 65mm and on my RX100 it never happens because the lens isn't long enough.

Paul Pasco said "through viewfinder with both eyes open, the size of objects appeared very close to the same" and I replied "With a 43mm lens, the sizes would appear even closer". Neither of us said they would appear exactly the same through the viewfinder as with the naked eye.

At 43mm the sizes would not appear closer. With a viewfinder magnification of 1 they will be the same size at 50mm. Most cameras have a viewfinder magnification below 1 so the sizes will appear the same at a focal length longer than 50mm. For them to be the same at 43mm you would need a viewfinder magnification of 1.16 which is not available on any FF camera.

So now you have a better idea of what I can see through the viewfinder of my own camera with my own eyes than I do. How did you get this super power, a radioactive lens maybe?

This conversation is over. It's not going anywhere and I no longer wish to exchange pedantries with you. It's a 2aste of time. Goodbye.

From an article called "Understanding Viewfinders":

Magnification: this refers to how big the viewfinder image appears to be in an absolute sense. Like a batting average, it’s usually expressed as some decimal fraction of one. 1X is the size that things appear to be when you look at them with your eye (a.k.a. “the naked eye”). Now, obviously, magnification also changes when you use different lens focal lengths — telephotos make things look bigger, wide-angles make things look smaller. So camera magnification is specified with a 50mm lens. Less often stated is that the lens must be set at infinity, because magnification also changes slightly depending on how close or far you focus the lens.

Let’s say a camera’s magnification is .75X. What this means is that your camera, with a 50mm lens on it, set at infinity, makes things appear to be three-quarters the size they look to be with your naked eye. .5X means half as big; .9X means nine-tenths as big. https://luminous-landscape.com/understanding-viewfinders/

I've read that 58mm lenses were desired by some because they provided life-size viewing on some cameras. For example, "The 58mm focal length provided 1:1 viewing on the Contax S focusing screen." https://casualphotophile.com/2019/02/13/carl-zeiss-jena-biotar-58mm-f-2-lens-review/

I don't know which SLR's in the 1970's Paul Pasco was thinking of, but my Pentax SP1000 had a .88X viewfinder magnification, and my Contax 139Q was .86X.  The 55mm lens on my Pentax would have been closer to life-size viewing than the 50mm lens on my Contax.

GossCTP Veteran Member • Posts: 5,673
Re: 6%
1

FrancoD wrote:

Phil A Martin wrote:

FrancoD wrote:

Phil A Martin wrote:

jrtrent wrote:

tko wrote:

You're thinking you need a 40 mm instead of 35 mm? Of what importance is this? How did you get this conclusion? How would a 85/80 = 6% difference in FL rock your world? I don't get this at all. It would seem like you think your numbers are better since they are "more rounded off," and you want lens manufacturers to come up with new products where the focal lengths are "prettier."

You may be right about the difference between 80 and 85 mm, but apparently there's a noticeable difference around 40mm:

"40mm is the "Perfect Normal" focal length for full-frame. Unlike 50mm lenses which often are too long or 35mm lenses which are often too wide, 40mm is always just right."

And that's from Ken Rockwell himself!

He's wrong, it's 43mm is actually the perfect focal length for full frame. It corresponds to the sensor diagonal of 43.27mm.

and that Pentax 43mm f/1.9 was so popular that dozens of people worldwide bought one.

It was an excellent lens on film and is no mean slouch on digital

no doubt but that was not my point.

What I was getting at is that because something makes sense /is right .. whatever, it does not mean that it will sell and if it does not sell there is no point in making it.

Plenty of 45mm lenses were made over the years. Moreso on rangefinders as the registration distance wasn't a factor.

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Panasonic Lumix DMC-LX5 Pentax K20D Pentax K-5 II Fujifilm X-H1 Pentax smc FA 50mm F1.4 +8 more
J A C S
J A C S Forum Pro • Posts: 19,595
Re: 6%
2

Phil A Martin wrote:

J A C S wrote:

Phil A Martin wrote:

jrtrent wrote:

tko wrote:

You're thinking you need a 40 mm instead of 35 mm? Of what importance is this? How did you get this conclusion? How would a 85/80 = 6% difference in FL rock your world? I don't get this at all. It would seem like you think your numbers are better since they are "more rounded off," and you want lens manufacturers to come up with new products where the focal lengths are "prettier."

You may be right about the difference between 80 and 85 mm, but apparently there's a noticeable difference around 40mm:

"40mm is the "Perfect Normal" focal length for full-frame. Unlike 50mm lenses which often are too long or 35mm lenses which are often too wide, 40mm is always just right."

And that's from Ken Rockwell himself!

He's wrong, it's 43mm is actually the perfect focal length for full frame. It corresponds to the sensor diagonal of 43.27mm.

You are both wrong. There is no such thing as a perfect FL. It is a superstition.

If you want to play word games, then fine. Enjoy yourself.

I only used the phrase "perfect" because Rockwell used it and I was replying to his quoted comment and not that I thought the 43mm focal length to be perfect focal length under all situations and circumstances.

Referring to KR is not a particularly strong argument...

Maybe I should have been clearer and said that 43mm is the ideal focal length for a standard lens that renders natural perspective on a 35mm or Full Frame camera?

What is a natural perspective and why is the diagonal magical? As weak as the KR argument is, this one is weaker.

Phil A Martin
Phil A Martin Veteran Member • Posts: 6,774
Re: 6%

J A C S wrote:

Phil A Martin wrote:

J A C S wrote:

Phil A Martin wrote:

jrtrent wrote:

tko wrote:

You're thinking you need a 40 mm instead of 35 mm? Of what importance is this? How did you get this conclusion? How would a 85/80 = 6% difference in FL rock your world? I don't get this at all. It would seem like you think your numbers are better since they are "more rounded off," and you want lens manufacturers to come up with new products where the focal lengths are "prettier."

You may be right about the difference between 80 and 85 mm, but apparently there's a noticeable difference around 40mm:

"40mm is the "Perfect Normal" focal length for full-frame. Unlike 50mm lenses which often are too long or 35mm lenses which are often too wide, 40mm is always just right."

And that's from Ken Rockwell himself!

He's wrong, it's 43mm is actually the perfect focal length for full frame. It corresponds to the sensor diagonal of 43.27mm.

You are both wrong. There is no such thing as a perfect FL. It is a superstition.

If you want to play word games, then fine. Enjoy yourself.

I only used the phrase "perfect" because Rockwell used it and I was replying to his quoted comment and not that I thought the 43mm focal length to be perfect focal length under all situations and circumstances.

Referring to KR is not a particularly strong argument...

I was not referring to KR, I was responding to his quoted comment.

Maybe I should have been clearer and said that 43mm is the ideal focal length for a standard lens that renders natural perspective on a 35mm or Full Frame camera?

What is a natural perspective

Natural perspective is when near and far objects bare the same relationship in the image, as they do with the naked eye.

and why is the diagonal magical? As weak as the KR argument is, this one is weaker.

It's not a question of magic, it's just that if you take the continuum of potential focal lengths, for a given sensor the focal length that matches the diagonal, is the median focal length and the transition point between wide angle and telephoto for that sensor.

For a full frame sensor, this will be approximately 43mm and on Pentax/Nikon/Fuji APSc sensor approximately 28mm.

SteveinLouisville
SteveinLouisville Senior Member • Posts: 1,243
From Rockwell's review of the 40mm pancake
4

"50mm stuck because it's much, much easier to clear the flipping mirror of an SLR with a 50mm lens, but the 40mm to 45mm range (precisely 43.27mm) is what's really normal for the 35mm full-frame."

Tempest, meet teapot.

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Gerry Winterbourne Forum Pro • Posts: 19,062
Re: 6%
1

Phil A Martin wrote:

J A C S wrote:

Phil A Martin wrote:

jrtrent wrote:

tko wrote:

You're thinking you need a 40 mm instead of 35 mm? Of what importance is this? How did you get this conclusion? How would a 85/80 = 6% difference in FL rock your world? I don't get this at all. It would seem like you think your numbers are better since they are "more rounded off," and you want lens manufacturers to come up with new products where the focal lengths are "prettier."

You may be right about the difference between 80 and 85 mm, but apparently there's a noticeable difference around 40mm:

"40mm is the "Perfect Normal" focal length for full-frame. Unlike 50mm lenses which often are too long or 35mm lenses which are often too wide, 40mm is always just right."

And that's from Ken Rockwell himself!

He's wrong, it's 43mm is actually the perfect focal length for full frame. It corresponds to the sensor diagonal of 43.27mm.

You are both wrong. There is no such thing as a perfect FL. It is a superstition.

If you want to play word games, then fine. Enjoy yourself.

I only used the phrase "perfect" because Rockwell used it and I was replying to his quoted comment and not that I thought the 43mm focal length to be perfect focal length under all situations and circumstances.

Maybe I should have been clearer and said that 43mm is the ideal focal length for a standard lens that renders natural perspective on a 35mm or Full Frame camera?

Well, that would have been clearer and - I think - nearer to what you meant than what you said. But it still misses the point that it's only true when the picture is viewed in a specific way.

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Gerry
________________________________________________________________________
I'm happy for anyone to edit any of my photos and display the results
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First camera 1953, first Pentax 1985, first DSLR 2006
http://www.pbase.com/gerrywinterbourne
gerry.winterbourne@ntlworld.com

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