Rethinking focal length conventions

Started 7 months ago | Discussions thread
Phil A Martin
Phil A Martin Veteran Member • Posts: 6,341
Re: 6%

Pixel Pooper wrote:

Phil A Martin wrote:

As explained above, this comment is irrelevant.

I assume that you would agree that wide angle lenses exagerate perspective? (It is part of the basic ABC of photography afterall) and as the focal length shortens, the angle of view increases and with it the exaggeration of perspective. Likewise with telephoto lenses, increasing the focal length narrows the angle of view and increasingly foreshortens perspective.

If you understand and agree with this basic photographic theory and there's no reason you shouldn't. Then you should agree that if we go through all the potential focal lengths for a given format, we will reach a point of cross over where the focal length neither exaggerates nor compresses the apparent perspective and that is what we call the standard lens. Which for 35mm/FF, will be in the 40-50mm range. The Pentax 43mm f/1.9 ltd being a good example of such a lens, because the focal length is almost identical to the negative/sensor diagonal of 43.27mm. Assuming the sensor to be 24x36mm, as they are claimed to be.

It depends on how the image is viewed. A focal length equal to the format diagonal gives a natural perspective when the viewing distance is equal to the image diagonal. Images viewed from closer have a shorter normal focal length, and images viewed from farther have a longer normal focal length.

People say this quite often here but where is your proof?

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