50mm "Normal" Lens... Ok, but "Normal" on FF or APS-C Sensor?

Started Nov 10, 2012 | Discussions thread
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jrtrent Veteran Member • Posts: 4,208
Re: 50mm "Normal" Lens... Ok, but "Normal" on FF or APS-C Sensor?

ljfinger wrote:

jrtrent wrote:


"A focal length approximating the diagonal dimension of the camera’s image plane will render an angle-of-view with negligible magnification—similar to normal human vision. Focal lengths numerically lower than normal will render negative magnification, resulting in wider angles-of-view (wide angle), while those numerically greater than normal render positive magnification, producing narrower angles-of-view (telephoto.)."

"A photographic lens provides a visual effect, making closely located subjects larger while remotely located subjects smaller. As the focal length becomes shorter in a wideangle lens, this perspective difference expands making closely located subjects even bigger and remotely located ones even smaller (exaggerated perspective). In contrast, in a telephoto lens, as focal lengths become longer, less difference is observed between close and distant subjects, making it appear as if they are closer regardless of the distance between them(compressed perspective)."

Pretty much everything from that tamron article is wrong. The second paragraph is totally and completely wrong. There's even an article here on DPR that's dedicated to demonstrating that it's wrong.

I appreciate your experience, passion, and sincerity, but I'm afraid I'm more likely to believe what lens manufacturers as well as my own experience tell me than to accept your statement that Tamron is wrong.

The article on perspective you refer to, even using its artificial environment with no background elements, confirms rather than debunks what Tamron said.  Compare pictures A and C, taken from the same distance.  The 33mm lens makes the objects look smaller and farther away from the camera while the 80mm lens makes them appear bigger and closer.  Picture B crops the 33mm picture to the same angle of view as the 80mm picture, so naturally the size and distance now appear the same.  In pictures C and D, the camera to subject distance has been changed to maintain the same image size of the closer object with both the shorter and longer lenses.  Despite the camera being closer to the more distant object when using the short lens, that more distant object actually looks smaller and farther away than in the picture taken with the longer lens.  Just as the Tamron article says, there is less difference between the near and far objects in the picture taken with the telephoto lens.

While recognizing that subject distances matter, the Tamron article is in agreement with Bockaert's statement that, "Images C and D show that a tele compresses perspective (makes subjects look closer to one another), while a wide angle exaggerates perspective (makes subjects look more separated) compared to the "normal" way we see things with the naked eye."

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