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edit approved Jul 12, 2019 at 21:32
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edit approved Jul 12, 2019 at 21:32
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From the Wikipedia pageMagnification Wikipedia page, I have the following equality  :

M = di/do = f/(do-f) = (di-f)/f

M = di/do = f/(do – f) = (di – f)/f

Withwith M the magnification, f the focal length, dodo the distance from the subject to the lens, and didi the distance from the lens to the sensor.

So, when the magnification is 1 we should have didi = dodo = 2f.

With my macro lens (EF 100mm f/2.8 L IS USM Macro), the minimum working distance (from subject to sensor) is 30cm, at this distance the magnification is 1. From what I unsderstand from the formula, this distance should be di+dodi + do = 4f = 40cm.

So I think I missing something, can someone explain where I'm wrong?

From the Wikipedia page, I have the following equality  :

M = di/do = f/(do-f) = (di-f)/f

With M the magnification, f the focal length, do the distance from the subject to the lens and di the distance from the lens to the sensor.

So, when the magnification is 1 we should have di = do = 2f.

With my macro lens (EF 100mm f/2.8 L IS USM Macro), the minimum working distance (from subject to sensor) is 30cm, at this distance the magnification is 1. From what I unsderstand from the formula, this distance should be di+do = 4f = 40cm.

So I think I missing something, can someone explain where I'm wrong?

From the Magnification Wikipedia page, I have the following equality:

M = di/do = f/(do – f) = (di – f)/f

with M the magnification, f the focal length, do the distance from the subject to the lens, and di the distance from the lens to the sensor.

So, when the magnification is 1 we should have di = do = 2f.

With my macro lens (EF 100mm f/2.8 L IS USM Macro), the minimum working distance (from subject to sensor) is 30cm, at this distance the magnification is 1. From what I unsderstand from the formula, this distance should be di + do = 4f = 40cm.

So I think I missing something, can someone explain where I'm wrong?

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mattdm
mattdm
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Magnification and Why doesn't the focus distance at which my lens has magnification 1 match the formula?

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gregseth
gregseth
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From the Wikipedia page, I have the following equality :

M = di/do = f/(do-f) = (di-f)/f

With M the magnification, f the focal length, do the distance from the subject to the lens and di the distance from the lens to the sensor.

So, when the magnification is 1 we should have di = do = 2f.

With my macro lens (EF 100mm f/2.8 MacroL IS USM Macro), the minimum working distance (from subject to sensor) is 30cm, at this distance the magnification is 1. From what I unsderstand from the formula, this distance should be di+do = 4f = 40cm.

So I think I missing something, can someone explain where I'm wrong?

From the Wikipedia page, I have the following equality :

M = di/do = f/(do-f) = (di-f)/f

With M the magnification, f the focal length, do the distance from the subject to the lens and di the distance from the lens to the sensor.

So, when the magnification is 1 we should have di = do = 2f.

With my macro lens (EF 100mm f/2.8 Macro IS USM), the minimum working distance (from subject to sensor) is 30cm, at this distance the magnification is 1. From what I unsderstand from the formula, this distance should be di+do = 4f = 40cm.

So I think I missing something, can someone explain where I'm wrong?

From the Wikipedia page, I have the following equality :

M = di/do = f/(do-f) = (di-f)/f

With M the magnification, f the focal length, do the distance from the subject to the lens and di the distance from the lens to the sensor.

So, when the magnification is 1 we should have di = do = 2f.

With my macro lens (EF 100mm f/2.8 L IS USM Macro), the minimum working distance (from subject to sensor) is 30cm, at this distance the magnification is 1. From what I unsderstand from the formula, this distance should be di+do = 4f = 40cm.

So I think I missing something, can someone explain where I'm wrong?

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gregseth
gregseth
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