A Fast Fifty Is Really A Fast 75mm

Sean Nelson · 12-03-2008, 10:17 AM

Originally posted by audiobomber

Photographers use this effect in selecting "portrait length" lenses. The most accurate portrait will be obtained with a normal lens. A wide angle lens will stretch a person's face in an unflattering manner, and a telephoto lens will flatten the face in a flattering manner.

Originally posted by Marc Sabatella

As I have said many times now, this is quite simply a myth. it's not about focal length, it's about distance to subject. Changing focal lenth has *no effect whatsoever* on perspective.

Audiobomber is coming from the point of view of maintaining a constant subject size in the frame. In that scenario a wide lens requires moving closer to the subject, changing the perspective, and vice versa.

You're both right, just from differenct "perspectives".

audiobomber · 12-03-2008, 10:41 AM

Originally posted by Sean Nelson

Audiobomber is coming from the point of view of maintaining a constant subject size in the frame. In that scenario a wide lens requires moving closer to the subject, changing the perspective, and vice versa.

You're both right, just from differenct "perspectives".

I believe the statements are contradictory. Subject size is only relevant in its relation to the size of the other items in the image.

A wide angle lens creates perspective distortion, a normal lens doesn't. A wide angle lens changes the relative sizes of the subject and the background. That's perspective distortion, and it is not "normal".

Tokina · 12-03-2008, 10:49 AM

Originally posted by Sean Nelson

Audiobomber is coming from the point of view of maintaining a constant subject size in the frame. In that scenario a wide lens requires moving closer to the subject, changing the perspective, and vice versa.

You're both right, just from differenct "perspectives".

No. "A wide angle lens will stretch a person's face in an unflattering manner, and a telephoto lens will flatten the face in a flattering manner." is simply an inaccurate statement. It's all about distance to subject. "Accurate portrait" doesn't exist. It's a choice of the photographer.

Tokina · 12-03-2008, 10:49 AM

Originally posted by audiobomber

I believe the statements are contradictory. Subject size is only relevant in its relation to the size of the other items in the image.

A wide angle lens creates perspective distortion, a normal lens doesn't. A wide angle lens changes the relative sizes of the subject and the background. That's perspective distortion, and it is not "normal".

"Normal perspective" does not exist.

Michael Barker · 12-03-2008, 11:11 AM

Originally posted by Tokina

No. "A wide angle lens will stretch a person's face in an unflattering manner, and a telephoto lens will flatten the face in a flattering manner." is simply an inaccurate statement. It's all about distance to subject. "Accurate portrait" doesn't exist. It's a choice of the photographer.

Honestly I think you guys have a point and it's true that many people don't understand that fact.

But, there is another side to it - think of a photographer who only takes pictures of people's faces, and the person's face always fills the frame. In a practical sense, to that photographer, the change in subject distance is not a parameter! It is not an option! For such a photographer, each focal length has an associated subject distance, and therefore an associated perspective.

Stop being so objective! Thinking subjectively is perfectly valid.

Best regards...

m8o · 12-03-2008, 11:17 AM

Originally posted by Michael Barkowski

And then adjust your 50mm by the 0.85x magnification of the viewfinder and you get 42mm ... which is still quite long ... interesting experiment though.

? Is that what it is for the K100D/K200D? I have the K10D which is 95% viewfinder coverage. I was going to make a statement about that differential but didn't want to "muddy the waters".

To address some of the other points made to no particular one person, yes, it's the relation of closer objects to further away objects -- in how their relational sizes are "seen" thru the lens and affected by perspective from the lens's focal length being "wider" or "longer" than [ahem] "normal" -- that viewing a chair at an isometric angle is supposed to capture. Any significantly sized object relatively close to you can be the subject, or two objects with some space between them (isometric angle then not necessary). If you view say a [one] short candle however, the effect won't be very noticeable if at all. One can do the same by snapping an eye-piece that has 1x magnification (I only have a 3x eye-piece) to the back of a zoom and zooming in & out with one eye while keeping the other naked eye on the same subject if one feels better about removing the camera's mirror box from the whole equation.

I just don't get the whole debate of "what is the normals focal length that gives a perspective the same as the naked eye to all objects in both the foreground & background" when this effect of focal length can so easily be observed and truth be told by this method. In short to answer the OP of " A Fast Fifty Is Really A Fast 75mm", Answer: Yes as far as crop & what fits in the frame; No as far as perspective as a 50mm lens still projecting the same subject perspective onto the material reacting to the light and turning it into an image; when using digital, you just see less of that projected image because of the smaller sensor when compared to 35mm film... which is where the ##mm nomenclature comes from.

audiobomber · 12-03-2008, 11:19 AM

Originally posted by Marc Sabatella

Take pictures of a person using your favorite wide angle (well, not a fisheye) lens and your favorite telephoto lens, *without* changing your position. Now crop the image from the wide angle lens to give the sme FOV as the telephoto. There will be *no difference whatsoever* in the perspective of the two pictures.

I disagree. The relation of the nose to the back of the head will change very slightly, but probably not enough to notice under those conditions. That's not the way to show perspective distortion.

Take a photo a subject in front of and to the side of a landscape using your widest angle lens. Let's say the subject is the hood ornament on your new SUV and the background is a mountain. Take the same shot from the same position using a normal lens and then your longest telephoto lens. Now print all of them (or display at the same size on your monitor). Measure the size of the foreground ornament and the size of the distant mountain. The ratio of the sizes will change based on focal length. The mountain will look smaller in proportion to the car in the wide angle lens than it will in the telephoto lens. With the normal lens the relative size of the car will remain in proportion to the relative size of the mountain. In other words, the image will be in exactly the same proportion as you saw in the scene with your eye. The wide and telephoto images will exhibit perspective distortion in relation to your normal eyesight.

Last edited by audiobomber; 12-03-2008 at 11:40 AM.

Tokina · 12-03-2008, 11:30 AM

Originally posted by Michael Barkowski

Honestly I think you guys have a point and it's true that many people don't understand that fact.

But, there is another side to it - think of a photographer who only takes pictures of people's faces, and the person's face always fills the frame. In a practical sense, to that photographer, the change in subject distance is not a parameter! It is not an option! For such a photographer, each focal length has an associated subject distance, and therefore an associated perspective.

Stop being so objective! Thinking subjectively is perfectly valid.

Best regards...

Yeah. If i'm going to take portraits I will most likely use focal lengths 50-90mm (crop sensor). That gives the right working distance (perspective) for conventional portraits.

audiobomber · 12-03-2008, 11:44 AM

Originally posted by Michael Barkowski

But, there is another side to it - think of a photographer who only takes pictures of people's faces, and the person's face always fills the frame. In a practical sense, to that photographer, the change in subject distance is not a parameter! It is not an option! For such a photographer, each focal length has an associated subject distance, and therefore an associated perspective.

Like this. The WA is weird, the 50mm is the most accurate, the telephotos are most flattering. Untitled Document

Tokina · 12-03-2008, 11:45 AM

Originally posted by audiobomber

I disagree. The relation of the nose to the back of the head will change very slightly, but probably not enough to notice under those conditions. That's not the way to show perspective distortion.

Take a photo a subject in front of and to the side of a landscape using your widest angle lens. Let's say the subject is the hood ornament on your new SUV and the background is a mountain. Take the same shot from the same position using a normal lens and then your longest telephoto lens. Now print all of them (or display at the same size on your monitor). Measure the size of the foreground ornament and the size of the distant mountain. The ratio of the sizes will change based on focal length. The mountain will look smaller in proportion to the car in the wide angle lens than it will in the telephoto lens. With the normal lens the relative size of the car will remain in proportion to the relative size of the mountain. In other words, the image will be in exactly the same proportion as you saw in the scene with your eye. The wide and telephoto images will exhibit perspective distortion in relation to your normal eyesight.

I think you should do that test yourself. Ratios in pictures don't change if taken from the same spot.

Michael Barker · 12-03-2008, 11:49 AM

Originally posted by m8o

? Is that what it is for the K100D/K200D? I have the K10D which is 95% viewfinder coverage. I was going to make a statement about that differential but didn't want to "muddy the waters".

I was talking about magnification, and I think that's what you meant as well...
Coverage isn't relevant if you're talking about subject size, but yes I believe K10D is 0.95 magnification, 95% coverage, while my K100D is 0.85x magnification, 96% coverage. I'm taking the values from a helpful chart here:
Standard versus Enhanced Viewfinders - Size Matters :: Wetpixel.com

Michael Barker · 12-03-2008, 11:54 AM

Originally posted by audiobomber

Like this. The WA is weird, the 50mm is the most accurate, the telephotos are most flattering. Untitled Document

Yes, exactly. Although the linked page is not very scientific, in that it kind of exaggerates it with different lighting (look at the reflected light on the right side of the nose - it's not there in every shot), and expression/pose (the left-right angle of the head is obviously different in some of them).

So the statement "A wide angle lens will stretch a person's face in an unflattering manner, and a telephoto lens will flatten the face in a flattering manner." is not "simply inaccurate", although the statement makes unspoken assumptions and is therefore subjective.

P.S. I don't think the exaggeration was intended. I think the lighting setup stayed fixed, but the model unconsciously changed her expression and head angle. For example, her eyes started to close - a defense mechanism.

Tokina · 12-03-2008, 11:54 AM

Originally posted by audiobomber

Like this. The WA is weird, the 50mm is the most accurate, the telephotos are most flattering. Untitled Document

No... that may be your opinion but the beauty is in the eye of the beholder. Just like perspective always is

Additional question: Do you like to watch your wife from far away with binoculars? Or from "accurate distance"

Michael Barker · 12-03-2008, 12:08 PM

Originally posted by Tokina

No... that may be your opinion but the beauty is in the eye of the beholder. Just like perspective always is

Now at least you're being subjective

audiobomber · 12-03-2008, 12:16 PM

Originally posted by Tokina

No... that may be your opinion but the beauty is in the eye of the beholder.

That's true.

Originally posted by Tokina

Just like perspective always is

That's incorrect. Perspective is very real and has been understood in art for millenia. You're not a very thoughtful person are you Tokina? Why don't you do some research instead of this one-line sniping?

I will do the measurement test I proposed when I have time.

12-03-2008, 11:17 AM	#111
m8o Veteran Member Join Date: Jul 2007 Location: 40°-55'-44" N / 73°-24'-07" W [on LI] Photos: Gallery \| Albums Posts: 3,092	Originally posted by Michael Barkowski And then adjust your 50mm by the 0.85x magnification of the viewfinder and you get 42mm ... which is still quite long ... interesting experiment though. ? Is that what it is for the K100D/K200D? I have the K10D which is 95% viewfinder coverage. I was going to make a statement about that differential but didn't want to "muddy the waters". To address some of the other points made to no particular one person, yes, it's the relation of closer objects to further away objects -- in how their relational sizes are "seen" thru the lens and affected by perspective from the lens's focal length being "wider" or "longer" than [ahem] "normal" -- that viewing a chair at an isometric angle is supposed to capture. Any significantly sized object relatively close to you can be the subject, or two objects with some space between them (isometric angle then not necessary). If you view say a [one] short candle however, the effect won't be very noticeable if at all. One can do the same by snapping an eye-piece that has 1x magnification (I only have a 3x eye-piece) to the back of a zoom and zooming in & out with one eye while keeping the other naked eye on the same subject if one feels better about removing the camera's mirror box from the whole equation. I just don't get the whole debate of "what is the normals focal length that gives a perspective the same as the naked eye to all objects in both the foreground & background" when this effect of focal length can so easily be observed and truth be told by this method. In short to answer the OP of " A Fast Fifty Is Really A Fast 75mm", Answer: Yes as far as crop & what fits in the frame; No as far as perspective as a 50mm lens still projecting the same subject perspective onto the material reacting to the light and turning it into an image; when using digital, you just see less of that projected image because of the smaller sensor when compared to 35mm film... which is where the ##mm nomenclature comes from. Last edited by m8o; 12-03-2008 at 11:33 AM.

12-03-2008, 11:44 AM	#114
audiobomber Veteran Member Join Date: May 2008 Location: Sudbury, Ontario Photos: Albums Posts: 6,806	Originally posted by Michael Barkowski But, there is another side to it - think of a photographer who only takes pictures of people's faces, and the person's face always fills the frame. In a practical sense, to that photographer, the change in subject distance is not a parameter! It is not an option! For such a photographer, each focal length has an associated subject distance, and therefore an associated perspective. Like this. The WA is weird, the 50mm is the most accurate, the telephotos are most flattering. Untitled Document Last edited by audiobomber; 12-03-2008 at 11:50 AM.

12-03-2008, 11:54 AM	#117
Michael Barker Senior Member Join Date: Nov 2006 Location: Markham, Ontario Photos: Gallery \| Albums Posts: 185	Originally posted by audiobomber Like this. The WA is weird, the 50mm is the most accurate, the telephotos are most flattering. Untitled Document Yes, exactly. Although the linked page is not very scientific, in that it kind of exaggerates it with different lighting (look at the reflected light on the right side of the nose - it's not there in every shot), and expression/pose (the left-right angle of the head is obviously different in some of them). So the statement "A wide angle lens will stretch a person's face in an unflattering manner, and a telephoto lens will flatten the face in a flattering manner." is not "simply inaccurate", although the statement makes unspoken assumptions and is therefore subjective. P.S. I don't think the exaggeration was intended. I think the lighting setup stayed fixed, but the model unconsciously changed her expression and head angle. For example, her eyes started to close - a defense mechanism. Last edited by Michael Barker; 12-03-2008 at 12:02 PM.

12-03-2008, 11:54 AM	#118
Tokina Junior Member Join Date: Jan 2008 Location: Finland Posts: 49	Originally posted by audiobomber Like this. The WA is weird, the 50mm is the most accurate, the telephotos are most flattering. Untitled Document No... that may be your opinion but the beauty is in the eye of the beholder. Just like perspective always is Additional question: Do you like to watch your wife from far away with binoculars? Or from "accurate distance" Last edited by Tokina; 12-03-2008 at 12:14 PM.

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12-03-2008, 10:17 AM	#106
Sean Nelson Veteran Member Join Date: Sep 2008 Location: Vancouver BC Canada Posts: 353	Originally posted by audiobomber Photographers use this effect in selecting "portrait length" lenses. The most accurate portrait will be obtained with a normal lens. A wide angle lens will stretch a person's face in an unflattering manner, and a telephoto lens will flatten the face in a flattering manner. Originally posted by Marc Sabatella As I have said many times now, this is quite simply a myth. it's not about focal length, it's about distance to subject. Changing focal lenth has no effect whatsoever on perspective. Audiobomber is coming from the point of view of maintaining a constant subject size in the frame. In that scenario a wide lens requires moving closer to the subject, changing the perspective, and vice versa. You're both right, just from differenct "perspectives".

12-03-2008, 10:41 AM	#107
audiobomber Veteran Member Join Date: May 2008 Location: Sudbury, Ontario Photos: Albums Posts: 6,806	Originally posted by Sean Nelson Audiobomber is coming from the point of view of maintaining a constant subject size in the frame. In that scenario a wide lens requires moving closer to the subject, changing the perspective, and vice versa. You're both right, just from differenct "perspectives". I believe the statements are contradictory. Subject size is only relevant in its relation to the size of the other items in the image. A wide angle lens creates perspective distortion, a normal lens doesn't. A wide angle lens changes the relative sizes of the subject and the background. That's perspective distortion, and it is not "normal".

12-03-2008, 10:49 AM	#108
Tokina Junior Member Join Date: Jan 2008 Location: Finland Posts: 49	Originally posted by Sean Nelson Audiobomber is coming from the point of view of maintaining a constant subject size in the frame. In that scenario a wide lens requires moving closer to the subject, changing the perspective, and vice versa. You're both right, just from differenct "perspectives". No. "A wide angle lens will stretch a person's face in an unflattering manner, and a telephoto lens will flatten the face in a flattering manner." is simply an inaccurate statement. It's all about distance to subject. "Accurate portrait" doesn't exist. It's a choice of the photographer.

12-03-2008, 10:49 AM	#109
Tokina Junior Member Join Date: Jan 2008 Location: Finland Posts: 49	Originally posted by audiobomber I believe the statements are contradictory. Subject size is only relevant in its relation to the size of the other items in the image. A wide angle lens creates perspective distortion, a normal lens doesn't. A wide angle lens changes the relative sizes of the subject and the background. That's perspective distortion, and it is not "normal". "Normal perspective" does not exist.

12-03-2008, 11:11 AM	#110
Michael Barker Senior Member Join Date: Nov 2006 Location: Markham, Ontario Photos: Gallery \| Albums Posts: 185	Originally posted by Tokina No. "A wide angle lens will stretch a person's face in an unflattering manner, and a telephoto lens will flatten the face in a flattering manner." is simply an inaccurate statement. It's all about distance to subject. "Accurate portrait" doesn't exist. It's a choice of the photographer. Honestly I think you guys have a point and it's true that many people don't understand that fact. But, there is another side to it - think of a photographer who only takes pictures of people's faces, and the person's face always fills the frame. In a practical sense, to that photographer, the change in subject distance is not a parameter! It is not an option! For such a photographer, each focal length has an associated subject distance, and therefore an associated perspective. Stop being so objective! Thinking subjectively is perfectly valid. Best regards...

12-03-2008, 11:19 AM	#112
audiobomber Veteran Member Join Date: May 2008 Location: Sudbury, Ontario Photos: Albums Posts: 6,806	Originally posted by Marc Sabatella Take pictures of a person using your favorite wide angle (well, not a fisheye) lens and your favorite telephoto lens, without changing your position. Now crop the image from the wide angle lens to give the sme FOV as the telephoto. There will be no difference whatsoever in the perspective of the two pictures. I disagree. The relation of the nose to the back of the head will change very slightly, but probably not enough to notice under those conditions. That's not the way to show perspective distortion. Take a photo a subject in front of and to the side of a landscape using your widest angle lens. Let's say the subject is the hood ornament on your new SUV and the background is a mountain. Take the same shot from the same position using a normal lens and then your longest telephoto lens. Now print all of them (or display at the same size on your monitor). Measure the size of the foreground ornament and the size of the distant mountain. The ratio of the sizes will change based on focal length. The mountain will look smaller in proportion to the car in the wide angle lens than it will in the telephoto lens. With the normal lens the relative size of the car will remain in proportion to the relative size of the mountain. In other words, the image will be in exactly the same proportion as you saw in the scene with your eye. The wide and telephoto images will exhibit perspective distortion in relation to your normal eyesight. Last edited by audiobomber; 12-03-2008 at 11:40 AM.

12-03-2008, 11:30 AM	#113
Tokina Junior Member Join Date: Jan 2008 Location: Finland Posts: 49	Originally posted by Michael Barkowski Honestly I think you guys have a point and it's true that many people don't understand that fact. But, there is another side to it - think of a photographer who only takes pictures of people's faces, and the person's face always fills the frame. In a practical sense, to that photographer, the change in subject distance is not a parameter! It is not an option! For such a photographer, each focal length has an associated subject distance, and therefore an associated perspective. Stop being so objective! Thinking subjectively is perfectly valid. Best regards... Yeah. If i'm going to take portraits I will most likely use focal lengths 50-90mm (crop sensor). That gives the right working distance (perspective) for conventional portraits.

12-03-2008, 11:45 AM	#115
Tokina Junior Member Join Date: Jan 2008 Location: Finland Posts: 49	Originally posted by audiobomber I disagree. The relation of the nose to the back of the head will change very slightly, but probably not enough to notice under those conditions. That's not the way to show perspective distortion. Take a photo a subject in front of and to the side of a landscape using your widest angle lens. Let's say the subject is the hood ornament on your new SUV and the background is a mountain. Take the same shot from the same position using a normal lens and then your longest telephoto lens. Now print all of them (or display at the same size on your monitor). Measure the size of the foreground ornament and the size of the distant mountain. The ratio of the sizes will change based on focal length. The mountain will look smaller in proportion to the car in the wide angle lens than it will in the telephoto lens. With the normal lens the relative size of the car will remain in proportion to the relative size of the mountain. In other words, the image will be in exactly the same proportion as you saw in the scene with your eye. The wide and telephoto images will exhibit perspective distortion in relation to your normal eyesight. I think you should do that test yourself. Ratios in pictures don't change if taken from the same spot.

12-03-2008, 11:49 AM	#116
Michael Barker Senior Member Join Date: Nov 2006 Location: Markham, Ontario Photos: Gallery \| Albums Posts: 185	Originally posted by m8o ? Is that what it is for the K100D/K200D? I have the K10D which is 95% viewfinder coverage. I was going to make a statement about that differential but didn't want to "muddy the waters". I was talking about magnification, and I think that's what you meant as well... Coverage isn't relevant if you're talking about subject size, but yes I believe K10D is 0.95 magnification, 95% coverage, while my K100D is 0.85x magnification, 96% coverage. I'm taking the values from a helpful chart here: Standard versus Enhanced Viewfinders - Size Matters :: Wetpixel.com

12-03-2008, 12:08 PM	#119
Michael Barker Senior Member Join Date: Nov 2006 Location: Markham, Ontario Photos: Gallery \| Albums Posts: 185	Originally posted by Tokina No... that may be your opinion but the beauty is in the eye of the beholder. Just like perspective always is Now at least you're being subjective

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12-03-2008, 12:16 PM	#120
audiobomber Veteran Member Join Date: May 2008 Location: Sudbury, Ontario Photos: Albums Posts: 6,806	Originally posted by Tokina No... that may be your opinion but the beauty is in the eye of the beholder. That's true. Originally posted by Tokina Just like perspective always is That's incorrect. Perspective is very real and has been understood in art for millenia. You're not a very thoughtful person are you Tokina? Why don't you do some research instead of this one-line sniping? I will do the measurement test I proposed when I have time.