The fallacy of 35mm "equivalent focal lengths"

Started 3 months ago | Discussions thread
OP Tony Beach Forum Pro • Posts: 11,935
Re: Even though you're right, you're actually wrong

Lee Jay wrote:

Tony Beach wrote:

Lee Jay wrote:

Tony Beach wrote:

Lee Jay wrote:

When I crop, my 35mm-equivalent FOV

Even a lens used on 35mm format can have its equivalent FOV changed. The issue then becomes how much latitude you have in doing that. Compared to my S95, my 50mm f/1.8D lens just became a 50mm-150mm equivalent lens.

No way.

This is the previously shown crop from the S95 taken at 22.5mm ("105mm focal length equivalent") next to a crop from the the NIKKOR 50/1.8D using my D800; both at 100%.

You've done something wrong. You've got 4.6MP vs 12MP and they are the same size. Can't be.

You missed the relationship between pixel density and focal length. The S95 has 2.4x as much pixel density as the D800, so 22.5mm on the S95 will result in a 100% crop equal to a 100% crop from a D800 using a 54mm lens.

215mm at 16MP but with 5.6x crop on the left, 600mm at 20MP but with 1.6x crop on the right. So, that's 16MP at 1200mm equivalent vs 20MP at 960mm equivalent, and the size and resolving power are similar even if the tone and contrast are a bit different because of the different rendering engines.

It's not a bad result.

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tko
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