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# Lenses for photographing people...

Started Apr 8, 2013 | Discussions thread
Re: Lenses for photographing people...

clengman wrote:

clengman wrote:

The full frame equivalent of ideal focal length for portraits is < 50mm. It has only to do with rendering the subject accurately without distortion. That's it.

This is bull. First, where do you come up with "less than 50mm?" Second, what's your definition of rendering accurately? If you take a head shot with a 14mm lens, the camera just recorded exactly what that subject looks like from that distance. That is an accurate rendering. The features may appear distorted relative to the image you have of that person in your mind's eye, but if you put your eye at the same distance that the camera was when you took that head shot at 14mm, your eye will see the same "distortion" that the camera did.

You're talking about aesthetics, not accuracy. The camera is always accurate. The human eye/brain combination applies all sorts of non-optical a priori information before presenting the "perception" that you think you are "seeing".

Um the opening in the symbol is greater than.

http://www.mathsisfun.com/equal-less-greater.html

Distortion...

http://en.wikipedia.org/wiki/Wide-angle_lens

The camera captures a flat plane, a lens adds focal length, a lens is not perfect and can add distortion. In the case of wide angles this can be bad up close for portraits if you intend to be try and capture a faithful head shot for instance.

Sorry buddy that's a "less than" as in 5 < 10.

Quote from the link I gave you, math is fun:

Changing Sides

We saw in that previous example that when we change sides we flipped the symbol as well.

This:   Becky Spends > \$0 (Becky spends greater than \$0) is the same as this:   \$0 < Becky Spends (\$0 is less than what Becky spends)

Focal length doesn't add distortion.

Wikipedia:

The focal length of a lens determines the magnification at which it images distant objects. It is equal to the distance between the image plane and a pinhole that images distant objects the same size as the lens in question. For rectilinear lenses (that is, with no image distortion), the imaging of distant objects is well modelled as a pinhole camera model.[3] This model leads to the simple geometric model that photographers use for computing the angle of view of a camera; in this case, the angle of view depends only on the ratio of focal length to film size. In general, the angle of view depends also on the distortion.

Rectilinear lens

In photography, a rectilinear lens is a photographic lens that yields images where straight features, such as the walls of buildings, appear with straight lines, as opposed to being curved. In other words, it is a lens with little or no barrel or pincushion distortion. At particularly wide angles, however, the rectilinear perspective will cause objects to appear increasingly stretched and enlarged as they near the edge of the frame. These types of lenses are often used to create forced perspective effects.

So I suppose a stretched face isn't distorted?

The camera's position relative to the subject can give the appearance of distortion. People think that focal length adds distortion because you have to move closer to the subject for equal framing with a wider lens compared to a longer lens. That's it.

And this is different. Your distance relative to the subject while keeping the same framing gives a different look to the image. Wider angles tend to distort the image more and more the wider it gets. 50mm and above are typically less likely to exhibit this behavior giving a more accurate representation of your subject.

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