Hyperfocal technique

[potterm]

Originally Posted by vandergus

The mistake that he makes is assuming that DoF is concerned with how much detail is being resolved on the sensor/film. In that case, no, the size of the film/sensor doesn't matter. But that isn't consistent with the definition of DoF. DoF is concerned with the apparent sharpness in the final print, so magnification must be taken into account. It's not about resolution, it's about what appears to be sharp. Small films/sensors are magnified more than large sensors/film so the DoF is different.

I'm sorry, I don't know how to explain it any more than that. I think you'll just have to do a lot more reading on the subject, from multiple sources, and perhaps you'll come to a different conclusion.

Seems pretty clear to me, and completely logical.

[ogram23]

Originally Posted by vandergus

The reference you gave has been disputed by many and I think if you poll the general knowledge out there, you will find that the majority disagree with mister Reichmann. He even seems to contradict himself in places.



The mistake that he makes is assuming that DoF is concerned with how much detail is being resolved on the sensor/film. In that case, no, the size of the film/sensor doesn't matter. But that isn't consistent with the definition of DoF. DoF is concerned with the apparent sharpness in the final print, so magnification must be taken into account. It's not about resolution, it's about what appears to be sharp. Small films/sensors are magnified more than large sensors/film so the DoF is different.

I'm sorry, I don't know how to explain it any more than that. I think you'll just have to do a lot more reading on the subject, from multiple sources, and perhaps you'll come to a different conclusion.

I'm sorry but after reading the article, it does make clear that the depth of field in the final print does depend on the magnification ( but can be "compensated" by viewing distance). In fact one sentence states that if he expects to magnify greater than normal he sets his hyperfocal distance by reference to a wider aperture that that he is shooting,thus giving an expected smaller DOF.

So do not see what the disagreement is about.

[chandrashekharbapat]

Dear Sir,
I think still you are under some confusion regarding depth of field and circle confusion.The depth of field does depend upon Focal length of the lens used, the aperture and the focussed distance. It does not depend upon how much enlargement is done. If you enlarge the picture then you must see it from the proper distance which depends upon the digonal of the print, the focal length used when the photograph was taken and the viewers distance from the print. There is a very good book named "The Science of Photography" and I request all the members to go through it. I have gone through many articles on the said subject, and unfortunately found that most of the readers are under many confusions. Another confusion is that the depth of field is devided in two parts 1/3rd is in front and 2/3rd is behind the fucused distance. It is not so. For a very few combinations i.e. combination of focal length, aperture and focused distance it is true. But exceptions does not prove the rule. You have to calculate the depth of field using proper formulae. If the members are interested I am ready let you know the formula.
Chandrashekhar Bapat

[jgredline]

Originally Posted by chandrashekharbapat

Dear Sir,
I think still you are under some confusion regarding depth of field and circle confusion.The depth of field does depend upon Focal length of the lens used, the aperture and the focussed distance. It does not depend upon how much enlargement is done. If you enlarge the picture then you must see it from the proper distance which depends upon the digonal of the print, the focal length used when the photograph was taken and the viewers distance from the print. There is a very good book named "The Science of Photography" and I request all the members to go through it. I have gone through many articles on the said subject, and unfortunately found that most of the readers are under many confusions. Another confusion is that the depth of field is devided in two parts 1/3rd is in front and 2/3rd is behind the fucused distance. It is not so. For a very few combinations i.e. combination of focal length, aperture and focused distance it is true. But exceptions does not prove the rule. You have to calculate the depth of field using proper formulae. If the members are interested I am ready let you know the formula.
Chandrashekhar Bapat

I would be interested in seeing what you have

[wobertc]

Hi,
Hyperfocal Distance is difficult to explain technically as there are so many variables-
Here is my simple illustrated explanation-
Normally you might take a landscape with the lens focussed on infinity (and f22)
See Image HFD-1
DOF is from about 12ft to infinity reading the distances opposite the DOF scale indicator for f22.
Now focus the lens on 12ft (the near distance for indicated DOF)
See Image HFD-2
Suddenly DOF is from about 6ft to infinity on the DOF scale.
SO IN PRACTICAL TERMS- focusing on 12ft (which is the Hyperfocal Distance here) has given us maximum DOF for this lens at f22. capturing everything from 6ft to infinity.

[kencaleno]

Originally Posted by wobertc

Hi,
Hyperfocal Distance is difficult to explain technically as there are so many variables-
Here is my simple illustrated explanation-
Normally you might take a landscape with the lens focussed on infinity (and f22)
See Image HFD-1
DOF is from about 12ft to infinity reading the distances opposite the DOF scale indicator for f22.
Now focus the lens on 12ft (the near distance for indicated DOF)
See Image HFD-2
Suddenly DOF is from about 6ft to infinity on the DOF scale.
SO IN PRACTICAL TERMS- focusing on 12ft (which is the Hyperfocal Distance here) has given us maximum DOF for this lens at f22. capturing everything from 6ft to infinity.

But.....You have not allowed for the facts that:

a) Not all lenses have a depth of field scale

b) Apertures smaller than F11,(f16;f22;f32 etc.,) give a greater depth of field,but suffer from diffraction,where you lose sharpness.

Regards, Ken

[vandergus]

Originally Posted by ogram23

So do not see what the disagreement is about.

You and me both.

[wobertc]

Hi, In reply to Kencaleno- who points out
a) no DOF on lenses- true!
b) diffraction at small apertures- true!
However my illustrations were made to appear simple to explain the practicalities-
a) I do not object to you using DOF 'Preview' button if your camera has one? and
b) yes I prefer to shoot a couple of stops away from smallest aperture for sharpness however the increased DOF given by using a small aperture might outweigh the slight loss from diffraction. When you are out there taking landscapes nobody wants to be looking up the books for tables of numbers- its a subjective feel for understanding that focusing somewhere about the 'hyperfocal distance' you will get the maximum near & far sharpness in the image. Loving the discussion (for a newbie!)

[roguegenius]

Interesting and understandable info. Thanks, guys!