Definition

[peter_muller1]

Am relatively new to the Forum. Have seen the word "hypofocal"

referred to in the context of focusing for landscapes, but can not

find a definition in any available dictionary. Would appreciate any

input as to what the term means. Thank you.

[m_.]

Normally this refers to the shortest distance (to your lens) that is within your DOF (depth of field). As opposed to hyperfocal distance which is the farest plane within the DOF.

[bob haight]

This refers to hyperfocal distance or the depth of field wich appears in apparent sharp focus. Great for landscapes with wide lens. Stop down to f11 or more and set the infinity marker on that fstop. The lens will then tell you what is in sharp focus (apparent as there is actually only one plane of exact sharp focus). Works great with a wide lens because at small apertures sharp focus at hyperfocus settings begins just a few feet or even inches from the lens. Hyperfocus thus relates to creating scenes where everything is in focus, not wide open selective focus shots. With the SWC, all I have is the viewfinder and take great(okay good) shots with just hyperfocal settings. Everything is in apparrent sharp focus from foreground to infinity. With normal lens the concept is the same but the closest sharp area is moveed considerably farther out, so all may not be in focus. But, you will not have as much near objects with the longer lenses. In a nutshell, the hyperfocus setting moves the zone of apparent sharp focus as close to the lens as possible for each fstop.

[bob haight]

My answer obviously referred to hyper not hypofocal.

[pdumais]

More specifically I believe the hyperfocal distance is the front end of your "in-focus" field when the back-end of your "in-focus" field is set at infinity. So it's the minimum "in-focus" distance when the back of your landscape (i. e. infinity) is "in-focus".

[photom]

At any particular distance that the camera is focused at (camera to subject distance) there is a theoretical zone in front and in back that other objects will appear "adequately" in focus - but not be truly in focus. How far up and back these zones extend depends on the definition of "in focus" (related to circle of confusion definition), camera to subject distance, film size, aperture setting, and focal length fo the lens. All of these are connected by math relationships.

 

Now, the hyperfocal distance is the unique camera to subject distance (point that the camera is actually focused on) so that the rear in focus zone is just at infinity. Another way of saying this is the unique camera to subject distance that maximizes the total in focus zone from front to rear. Everything behind the focus point will just be in focus. Focusing one foot farther from the camera location and the front zone edge moves away but infinity stays the same so the total zone shrinks. Focusing one foot closer and both the front zone and back zone shrink in size. The part to remember about the definition that is sometimes confused is that it is this unique camera to subject distance that maximizes the total in focus zone - not a distance to the front or rear zone, or the total size of the zone. Again, unique for a given single set of variables mentioned above (focal length, aperture, film size, COC).

[steve_levine]

Pat is correct,hyperfocal distance always includes infinity at one end.

[conrad]

Hyperfocal is a method of focusing used when you are photographing from within a hyperspace vortex. Due to the quantum-level effects to lightwaves caused by the vortex, everything will be both in focus and out of focus at the same time. Beware of entanglement as it will really screw with your style. Street photographers often must resort to hyperfocal methods in order to get properly focused pictures through the invisibility fields that they mentally project when out making pictures.

[robert_eastman]

I am assuming you did not make a typo when asking your question. If so I would have to say "hypofocal" is just such a typo or a misspelling of "hyperfocal". You got a bag of definitions for that already.

[andy_piper2]

I think there is a bias in some of these definitions - hyperfocal distance does NOT have to include infinity in its parameters - although it often does in landscape work.

 

The hyperfocal distance is that distance at which you should focus your lens in order that the DOF of your chosen aperture/lens will cover the farthest and nearest points that you want to appear sharp. The "farthest point" MAY or may NOT be infinity.

 

E.G. Let's work with my 21mm lens. If I want to photograph an agave 3 feet away against a background of rocks 15 feet away and have both be sharp, I must use an aperture of f/6.8 (call it f/8 to be safe) and focus at 5 feet. According to the DOF scale on the lens.

 

Notice that no part of my subject (except some insignificant sand) is actually AT 5 feet away. So I'm focused on a 'hyper-subject', not a real one - thus "hyperfocal" distance.

 

To get that agave sharp against an 'infinitely' distant background - say, a mountain range or clouds - I must use f/8, and refocus the lens out to 6 feet.

 

Using the hyperfocal distance makes the most EFFICIENT use of your available DOF, which extends both in front of and behind the actual focus point.

 

I COULD easily get that agave and infinity both "in focus" by simply focusing on the agave itself (3 feet) and stopping down to f/16.

 

But that would require a 2-4x longer exposure. By using the hyperfocal setting, I can get both ends of the range "sharp" with a wider aperture and shorter exposure, reducing blur from wind, mirror shake, etc, as well as reciprocity problems, or diffraction effects from the small aperture.

 

Most MF camera have DOF scales on the lenses. But if not, or with a view camera, you resort to DOF tables.

[andrew booth]

> can not find a definition in any available dictionary

<p>

For goodness sake Peter - you have the whole internet at your disposal, but you give

up when you can't find it in your dictionary?

<p>

Go to http://www.google.com/ and type 'hyperfocal' into the box.

<p>

Would an article like <a href="http://www.photofocus.com/zine7/

hyperfocal.html">this</a> go any way towards answering your question?

[steve_levine]

Not to argue but,the definition of hyperfocal point or distance is as follows:The nearest point to the camera which is considered acceptably sharp when the lens is focused at infinity.When a lens is focused on the hyperfocal point,DOF extends from a distance halfway between this point and the camera to infinity.Rack focusing a lens to gain more DOF when not including infinity,isnt the same as using the hyperfocal distance.

[conrad_hoffman]

With all these varied responses it's no wonder that beginners are completely confused by this term. So who do you trust to write the definitive definition? I usually go with the older Focal Encyclopedia, but this two part explanation may be no better than the rest:

 

"When a lens is focused on infinity, the depth of field extends from infinity to a point nearer the camera. The distance from the camera to this near limit of the sharp field is called the hyperfocal distance. If the lens is focused on the hyperfocal distance, the depth of field extends from half the hyperfocal distance to infinity."

 

It's in print, so it must be true? The usual method is to set the lens infinity mark on the far DOF mark for the aperture in use. The subject has to be at a distance somewhere between the two DOF marks.

[conrad_hoffman]

Er, wait a minute, that's what Steve said.. duh!

[andy_piper2]

Yeah - my bad.

 

THE official HYPERFOCAL DISTANCE definition does require that the 'far' distance in the range of DOF be infinity.

 

I guess for cases not involving infinity (street photography, etc.) you'd have to call the middle focusing distance a "hyperfocal-LIKE distance" or some such.

[pavelp]

See the next to last message in the following thread:

 

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=000jU0

[steve_levine]

Setting the focus to allow the maximum DOF without infinity,is called "zone" or "rack" focusing.This is commonly used as a poor man's auto focus.At weddings I often use a 35MM lens set to F8,this will have acceptable focus from 5-15 feet.(The "frame" of a 35MM lens is about 3-4 people wide at 10 feet.Armed with this info,it allows me to bang away without focusing.)

[peter_muller1]

Thank you all. By the way, Mr. Booth, the word I was researching was "hypofocal" not "hyperfocal", and I did try some of the electronic directories to no avail.

Regardless, thank you all for your comments.

[ronald_lee_klages]

Andy Piper has it right. Do your own tests.

Most DOF calculators use pretty loose COC numbers.

I shoot mainly ULF and 8X10 and make large prints.

My tests of the usefulness of the charts is in the mural viewing area. Most landscapes blown up to eight feet require a semblance of sharpness from the nearest desired object to infinity. Who said that animals who view a print form an improper distance should be cast out of the gene pool? Viewing large prints makes errors in focus and DOF calculations stand out.

The circle of confusion, COC, become evident even when viewed from the proper distance. An eight foot diagonal print from eight feet or so.

enlargement = viewing distance / focal length

viewing distance = focal length X enlargement

144" or 12" = 12" X 12

There are a number of usable DOF charts and calculators out there.

I like DUDAKS and use instead of the commonly employed .254 for a custom COC one half of that(.127). This is a more truthful number for closely examined prints. I have always been disappointed in the results of relying on calculations alone. Either infinity is fuzzy or the promised near range is unsharp. The view cameras movements greatly help this problem, but I try to stay within the optics best f stops and try not to push the outer coverage on the lens. Working on the edge of either produces inferior prints.