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DOF Question


jdlaing

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how many stops does the ND filter compensate and whats the shutter speed ?

 

ND2 compensates for 1 f-stop and doubles the shutter speed. So if the correct shutter speed should have been 1/8000 sec., you will need 1/4000 sec. instead with an ND2 filter. ND4 will give 1/2000 sec., and ND8 will give 1/1000 sec. And so on …

 

Edit:

Sorry, I misunderstood the question …

Edited by evikne
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So no matter the shutter speed depth of field is unchanged?

 

I am not sure that is correct. That would mean that aperture is solely responsible for depth of field but I am guessing their are other factors, diameter of glass, shutter speed, etc.

 

I truly don't know the correct answer but I would like a fact based response to resolve my curiosity.

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If I use a lens set to f/1.0 in broad daylight will the addition of a neutral density filter increase the depth of field?

 

No.

 

DOF is determined by:

 

1. Subject distance

2. Aperture

3. Focal length in relationship to subject distance

4. Subject structure

5. Subject contrast

6. Sensor or film

7. Magnification through the system (this covers sensor/film size)

8.The falloff of sharpness in the OOF areas in the lens design

9. Print size (see magnification)

10. The tolerance of the viewer for unsharpness.

 

But not by an ND filter, as long as you don't adjust the aperture but the shutter speed. Shutterspeed has absolutely nil effect on DOF. Using a contrast-enhancing filter like a polfilter or a yellow/red one in B&W can have an impact.

 

Don't forget that DOF is not an objective effect. It is the zone of unsharpness that is acceptable to the viewer and depends on the fact that the resolving power of the human eye is limited. Thus it is subjective and not precisely quantifyable. 

All seemingly objective and precise formulas can only approximate reality - that is why there are a considerable number of different ones.

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Just to be sure I'm on the same page
We're talking about shooting wide open and using an ND filter for 2 or 3 stops to achieve  shallow  DOF ?
The lack of contrast in film from long exposures is something else.

I would agree with jaapv's list.  I just don"t understand #4. Subject structure or # 5. Subject contrast.

I have always thought DOF was purely an issue of the "Math" and am hoping jaapv will explain how they effect  DOF.

I appreciate this group and am always learning.

 

 

Post 13... jaapv's list

DOF is determined by:

1. Subject distance

2. Aperture

3. Focal length in relationship to subject distance

4. Subject structure

5. Subject contrast

6. Sensor or film

7. Magnification through the system (this covers sensor/film size)

8.The falloff of sharpness in the OOF areas in the lens design

9. Print size (see magnification)

10. The tolerance of the viewer for unsharpness.

Edited by ECohen
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DOF on three large cubes (modern art, for arguments' sake)  will exhibit a very different DOF from a leafy forest. So will a grey misty scene do from a sunny beach scene.  (to take the it into the hypothetical extreme: an uniformly  grey image will have no structure, no contrast, but an infinite DOF)  It is, in the end, all about the impression of sharpness in the eye of the beholder.

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