Distortion based on Focal Length or FOV??

Started Mar 23, 2014 | Discussions thread
blue_skies
blue_skies Forum Pro • Posts: 11,473
Re: Distortion based on Focal Length or FOV??

zilver wrote:

I've been struggling to find one prime focal length for people shots in dimly lit environment (birthday at a restaurant, etc) because obviously people's faces do look better with little longer length lens but group and ambient shots require wider lens.

One thing then came into the curious mind, let's say that

17mm olympus lens on m43 = 34mm FOV

18mm fuji lens APS-C = 27mm FOV

24mm Sony full frame obviously = 24mm FOV

Which number affects the natural distortion of people's faces, the lens focal length or the FOV?

Does this mean that using 24mm full frame will get better perspective while getting wider scene??

Forgive me if I have't used the correct terminology in the question, but I hope the question on the concept is clear.

Thanks!

I assume that you are talking about rectilinear lenses, and not fisheye here.

Do you understand rectilinear projection? The closer you get to your subject, the more the edges will appear stretched. Move further back, and the effect is less.

If you take a wide angle shot from e.g. a nature scene, everything will kind of look in place. Also, there are few recognizable features that would lead to seeing distortion in nature.

Then take a wide angle shot of a group of people, and the people towards the edge will be strangely stretched, and appear fatter than those in the middle.

You can't really compensate for this in post if you want to maintain straight lines.

In FF terms, down to about 35mm is workable without much thought. Below that FL the effect gets progressively worse. At about 24mm it becomes a nuisance.

18mm on FF (12mm on APS-C) - does this car look normally proportioned to you?

Same 18mm FOV, you know it is stretched, but does it disturb here?

18mm FF view - feels distorted, does it not? The building is 'falling' backwards.

Same 18mm FF FOV - does it still seem distorted?

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Cheers,
Henry

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