DOF for macro lens

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pslaviero@interfree.it - 27 Nov 2006 15:34 GMT

Hi, I use a 60 mm Zeiss macro lens. I need to know the DOF of this lens
when used to take 1:1 macro picture. Thanks.
Z.

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bhup - 27 Nov 2006 16:33 GMT

depends on aperture

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> Hi, I use a 60 mm Zeiss macro lens. I need to know the DOF of this lens
> when used to take 1:1 macro picture. Thanks.
> Z.

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Peter Irwin - 27 Nov 2006 16:43 GMT

> Hi, I use a 60 mm Zeiss macro lens. I need to know the DOF of this lens
> when used to take 1:1 macro picture. Thanks.
> Z.

Depth of field should be plus or minus 3mm at f/8
and plus or minus 6mm at f/16. This is for a circle
of confusion of 0.03mm.

The focal length of the lens does not affect DOF in
macro work. You will get the same depth of field
at 1:1 reproduction with a 50mm or an 100mm lens.

Peter.

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Thomas T. Veldhouse - 27 Nov 2006 16:57 GMT

> The focal length of the lens does not affect DOF in
> macro work. You will get the same depth of field
> at 1:1 reproduction with a 50mm or an 100mm lens.

Somehow, this doesn't ring true with me. I have seen much less depth of field
with a 105mm macro (1:1) then with a 60mm macro (1:1) taken at the same
apeture. The angle of view is clearly different with the two lenses and that
should have a direct affect on depth of field.

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Colin_D - 27 Nov 2006 21:10 GMT

>> The focal length of the lens does not affect DOF in
>> macro work. You will get the same depth of field
[quoted text clipped - 4 lines]
> apeture. The angle of view is clearly different with the two lenses and that
> should have a direct affect on depth of field.

Ultimately, the DoF is proportional to the aperture F/no. and
reproduction ratio, and nothing to do with focal length. For a constant
aperture and repro ratio, and at the selected CoC, the DoF is
independent of the focal length. The apparent shallow DoF with long
lenses isn't due to the length, but to the decreased repro ratio.

The formula for Dof at close range is DoF=2 x F/no x CoC x ((1+m)/m^2)
where DoF and CoC are in the same measure, e.g. millimetres, and m is
the magnification, or repro ratio.

Note that F, the focal length, is not in the equation.

Colin D.

Reference: http://en.wikipedia.org/wiki/Depth_of_field

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Alan Browne - 28 Nov 2006 00:51 GMT

> The formula for Dof at close range is DoF=2 x F/no x CoC x ((1+m)/m^2)
> where DoF and CoC are in the same measure, e.g. millimetres, and m is
> the magnification, or repro ratio.
>
> Note that F, the focal length, is not in the equation.

You might use clearer notation, ITC. (F/no looks like F over no).

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Michael Benveniste - 28 Nov 2006 13:52 GMT

>> The focal length of the lens does not affect DOF in
>> macro work. You will get the same depth of field
>> at 1:1 reproduction with a 50mm or an 100mm lens.

> Somehow, this doesn't ring true with me. I have seen much less
> depth of field with a 105mm macro (1:1) then with a 60mm macro
> (1:1) taken at the same aperture. The angle of view is clearly
> different with the two lenses and that should have a direct
> affect on depth of field.

It has a minor effect. With the 105mm lens, fractionally more of
the depth of field is in front of the focal point rather than
behind it. I would not expect the difference to be noticeable
at 1:1, but I can't quantify it without knowning the actual
focal length at 1:1 of each lens. (At 1:1, Nikon's 60mm becomes
a 55mm and the 105mm lens shifts to about 80mm.)

I agree with the other responses that overall depth of field
is the same.

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