does the focal length change the perspective at a given distance? [duplicate]

Question

Situation A: 25mm lense, subject at 5 meters. Take a shot with the Subject covering half of the sensor.

Situation B: 50mm lense, subject at 5 meters, Take a shot with the Subject covering the Whole sensor, load in Photoshop, resize subject to the same size as if it was taken with the 25mm lense.

Forgetting about image quality, lense quality, aperture, edge distortion, image-degradation from resizing and taking into account only the proportion and perspective of the subject if the distance to the subject does not change, will I notice a difference in the two images, or will the result be identical?

I want to make composites, and I know that the subject is supposed to be placed 5 meters from the photographer on scene. If the vaniscing point is identical, then the only thing i have to take into account is that the subject should be at the very same distance when it is photographed in the studio.. If this is right, then it makes no difference what focal lenght I use, as long as the distance to the subject is the same... (obviously illumination and aperture and all the rest have to match..)

Answer 1

Your perspective will be the same in both photos. Perspective is dependent on distance alone.

With two photos taken from the same distance, after you crop the image to match the subject size, there will be virtually no difference in the final image.

Answer 2

One thing and one thing only determines perspective: Subject distance. Period.

For more please see:
Is there a difference between taking a far shot on a 50mm lens and a close shot on a 35mm lens?
Does wide angle equivalent in crop sensor skew image?
Can a telephoto lens have a wide field of view?
How does focal length change perspective?
Why is the background bigger and blurrier in one of these images?
What does it really mean that telephoto lenses "flatten" scenes?

Answer 3

For portraits (concerned with facial features), we say perspective is subject distance (we say always stand back 7 to 10 feet for proper portrait perspective of face). But for landscapes, obviously background and foreground distance can matter too. For example, we might intentionally stand up close to a foreground object in a wide landscape. Perspective is the relative size and alignment of all those features, due to their distances.

Perspective seen is simply due to where the camera stands in that mix.

The obvious reason that perspective depends only on where the camera stands is because all lenses obviously can only see the same scene when standing in that same spot. Lenses may see wider or more narrow, but the relative scene perspective they see is the same if standing in the same spot. Because there is nothing else to see there. To see anything different, we have to move the camera.

So, perspective is NOT about focal length, other than focal length can determine our choice of where the camera has to stand. Perspective is what the camera sees when standing there.

We see dumb "tests" of the same head and shoulders portrait taken with many different lenses, supposedly showing effect of focal length. But of course, not mentioned but what changed was where the camera had to stand to see the same head and shoulders crop. Where we stand affects perspective. Focal length only changes the magnification of it. You do want to stand back 7 to 10 feet for portraits. Then use whatever focal length that gives what you want to see, group or full length or a head shot, etc. 105mm was a popular full frame "portrait lens", only because it forced us to stand back at proper distance.

And if standing in the same spot, if we crop and enlarge a wide angle shot to match a telephoto shot, the view seen will be the same (if standing in the same spot). Because again, there is nothing else to be seen there.