Hyperfocal focusing: Use judgment first!

[P3D Dr. George A. Themelis <fj834@xxxxxxxxxxxxxxxxxxxxx>]

>Memorize the critical two or three hyperfocus settings. They are
>roughly: f/16 focused at 10 ft gives you 5 ft -> inf.
>         f/11 focused at 12 ft gives you 6 ft -> inf.
>         f/8  focused at 16 ft gives you 8 ft -> inf.

The book that I just read, convinced me about the potential misapplications
of the hyperfocal focusing.  I now believe that the photographer should use
judgment above the hyperfocal practice.  The question is, which is the main
object being photographed and what is the finest detail required to be
captured on film?  This question should always be kept in mind when doing
critical (in terms of sharpness/ resolution) work.

If I take a picture at f11 and my main object (say a person) is at 12 feet
then the hyperfocal focusing is, perhaps, a good choice.  However, consider
the following (real) situation:  I am at the top of mountain Washington,
looking down at the wonderful city of Baltimore, MD.  I want to capture the
city buildings that have a lot of fine detail.   About 12-15 feet from me
is the ground and a canon that helps put some foreground into the scene. 
If I use the hyperfocal setting and focus at 12 feet, I give priority to
the canon, which is not my main subject and which does not require much
detail in the first place.  In this case, it might be better to even focus
at infinity to get the most out of the city and be satisfied with the
detail in the canon.

One might object and say that by focusing at infinity I waste all the depth
of field that is beyond infinity.  That's true but when talking about DOF
we should not forget that the plane that is in exact focus will show more
detail than the plane at the edge of the field.  Why place the city at the
edge when it requires the most detail, just to maximize the DOF and put the
most detail in a place where it does no good?  Again, what is the main
subject and what is the finest detail required?

If you are using f16 and you are focused at 10 feet while your closest
object is just the ground at 7-10 feet, then you are short-changing your
infinity detail (if that is important for you).

>Use the camera's DOF scale, but 2 stops lower than indicated. In
>other words, use the f/8 markings when shooting at f/16, the f/5.6 mark
>when shooting at f/11, etc.

The author had an interesting comment about this, which can also be applied
to properly constructed DOF scales for more demanding applications.  He
said that his first reaction, after being disappointed by the results of
the hyperfocal setting, was to use the hyperfocal setting for the next
wider aperture.  He was surprised to find out that he only got a small
improvement (2x) even though he expected an order of magnitude (10x)
improvement.  Working the mathematics shows that this practice indeed
doubles the resolution.  He still was not happy until he realized that,
instead of focusing at 12 feet at f11, he needed to focus at infinity to
get the most detail out of the smallest details at infinity.  That is an
order of magnitude improvement, if not more.

Regarding diffraction effects, the author states that his experience with
35 mm lenses has convinced him that he gets the maximum sharpness at f8 or
f11.  Closing the aperture to f16 will resolve less detail, not more.  He
says that he does all his critical landscape work at f8 or f11 and usually
focused at infinity.  Many beginners make the mistake to favor very small
apertures (f16, f22) at ordinary (including infinity) scenes without
realizing that the excess DOF is not needed, the pictures are not going to
be any sharper, and also risking camera shake if the small apertures are
used at the expense of shutter speeds in the absence of a tripod.  (I have
many unsharp f16 and f22 pictures from my first rolls and have learned to
always favor faster shutter speeds over smaller apertures when hand-holding
the camera)

Again, the nature of the subject is of primary importance.  For most of my
table-tops or macro close-ups, depth of field is more important than fine
detail and I stop my macro lens to the smallest aperture (f22).  

The advice of focusing at infinity comes from a landscape photographer who
works with large prints where fine detail is important.  This is not my
typical photography but I learned a good lesson by reading his book.

-- George Themelis


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