Dof?


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grado

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Dec 28, 2003
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#1
Is it true that even for the same focal length, different lens have different DOF? And lets say if i use a 70mm lens on a Nikon D70, even though the focal length will increase to 105mm, the DOF remains as if it were the same 70mm lens? It seems like it is harder to get the beautiful shallow DOF I get with my minolta film camera...
 

loupgarou

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Sep 9, 2003
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imho
DOF is controlled by the ACTUAL focal length (not modified by FOV crop factor) and aperture and focusing point .

the shorter the focal length, the deeper the depth of field (which is why wide angles have huge DOF and p&s with their extremely short focal length)

the wider the aperture, the shallower the depth of field

focusing point: the closer you are to the minimum focusing distance for your lense, the shallower the dof.
 

grado

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Dec 28, 2003
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#4
loupgarou said:
imho
DOF is controlled by the ACTUAL focal length (not modified by FOV crop factor) and aperture and focusing point .

the shorter the focal length, the deeper the depth of field (which is why wide angles have huge DOF and p&s with their extremely short focal length)

the wider the aperture, the shallower the depth of field

focusing point: the closer you are to the minimum focusing distance for your lense, the shallower the dof.
I used to think so too, but from my limited experience so far, I don't think that your first sentence is true, because I can't seem to achieve the same bokeh as my film based camera with the same (x1.5) equivalent focal length.
 

#5
grado said:
I used to think so too, but from my limited experience so far, I don't think that your first sentence is true, because I can't seem to achieve the same bokeh as my film based camera with the same (x1.5) equivalent focal length.
You mean u tried 70mm on D70 and the same 70mm on your film camera and both lenses have the same aperture ?
 

clive

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Oct 9, 2002
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#7
to summarize for the benifit of all:

apparatus: say we have: film body, digital body(1.5xFLM), 70mm/f2 lens, 105mm/f2 lens

scene 1: film body + 105mm lens, shoot at f2.8

and

scene 2: digital body + 70mm lens, shoot at f2.


result: both shots will have
1. same effective angle of view
2. same DOF

:cheers: :vhappy: :cheergal: :) :cool:
 

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