Is there a definitive focal length for tight head shots...

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Originally Posted by Thomas Bertilsson

Incorrect. A 35mm lens on a 35mm camera has a different 'angle of view' compared to the human eye. With a 50mm lens you are roughly correct.

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Thomas, what I'm suggesting is that when "the camera's angle of view" matches "the viewers angle of view" (defined by print viewing distance and print size), the the print will look normal.

There are definitely limits to this, a 180 fish eye for example, but if viewing distance remains constant and print size increases a wider lenses can be used.

The flattening effect of the longer lenses that we are all so familiar with is because of the mismatch in camera angle of view vs print viewing angle.

The same math formula applies to both applications.

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Originally Posted by markbarendt

Thomas, what I'm suggesting is that when "the camera's angle of view" matches "the viewers angle of view" (defined by print viewing distance and print size), the the print will look normal.

There are definitely limits to this, a 180 fish eye for example, but if viewing distance remains constant and print size increases a wider lenses can be used.

The flattening effect of the longer lenses that we are all so familiar with is because of the mismatch in camera angle of view vs print viewing angle.

The same math formula applies to both applications.

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Sorry, Mark, I don't see it.
To me wide angle looks wide angle, normal looks normal, and telephoto looks telephoto.
What do you mean by viewer's angle of view? We can only look at a print one single way - with our eyes, and as far as I understand, they do not have the ability to adjust angle of view, like switching lenses on a camera. Please explain in very specific terms what you mean; if you have some sort of drawings or pictures to show what you mean that would help.

The viewers angle of view the angle defined by print width (or height) vs viewing distance (print to eye distance).

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Originally Posted by markbarendt

The viewers angle of view the angle defined by print width (or height) vs viewing distance (print to eye distance).

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I think your theory would work if it were a 3-dimensional object. But the print is 2-dimensional.

If you take a picture of the same scene, one with a 35mm lens, and the other with an 85mm lens, how exactly would you position the prints so that the perspective would be the same, with relation to the viewer?

All I can say Thomas is try it.

Oh no, brother, I don't have time. It's your claim; if you want us to believe you - convince me.

http://www.mcpactions.com/blog/2010/...rs-experiment/
http://photo.tutsplus.com/tutorials/...ffects-images/

I don't even know what it is you want me to do exactly. How do I position myself with relation to the examples, in order for them to look the same.

Thomas, Mark Barendt is correct. However, what he describes is ignored by most people viewing any photograph, painting or drawing. Perhaps viewing lines should be marked on gallery floors, but people would ignore them.

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Originally Posted by cliveh

Thomas, Mark Barendt is correct. However, what he describes is ignored by most people viewing any photograph, painting or drawing. Perhaps viewing lines should be marked on gallery floors, but people would ignore them.

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I'm not saying he isn't correct, but I don't understand it. Can you explain?

Thomas:

Mark is right.

Using the examples linked to as a reference, you no doubt understand that when the photographer took the photos, he/she had to stand at different distances from the subject in order to fill the frame with the head. As an example, he/she may have needed to stand 1 foot away when using the 24mm lens, 1.4 feet away with a 35mm lens, 2 feet away with a 50mm lens, etc. (example distances may be incorrect :).

If the photographer then printed each example to lifesize, and put them side by side on a board, for you to look at, the perspective would look natural to you if you viewed each print from the same distance as the original shot was taken from.

You would need to view each one with one eye closed, and the relative size of the subject would decrease as you stepped farther and farther away, but the relationship of the size of the different parts of the subject's face to each other would appear natural in each case.

Binocular vision and the brain's ability to interpret differences without prompting tend to make the perspective distortions less obvious than they might be, but this approach does work.

OK, now that's a great explanation, Matt. Thanks. I understand now, and hopefully many others (or was it just me being dense? ;))

I'll let others argue about the utility of knowing this.