hyperfocal distance

It's the point of focus where the maximum objects are in focus from the front of the lens to infinity. For example if I am taking a landscape shot I focus 2/3 of the way into the shot then reframe. I'm sure someone will be along shortly with a more technical answer.
 
ksebruce said:
It's the point of focus where the maximum objects are in focus from the front of the lens to infinity. For example if I am taking a landscape shot I focus 2/3 of the way into the shot then reframe. I'm sure someone will be along shortly with a more technical answer.
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I'm sorry to have to break it to you, but the old 1/3 - 2/3 rule is an old wives' tale based on an inadequate understanding of the maths of DOF.

A while ago I had a slow day in the office so I did some calculations. (Well actually DOFMaster did.) Suppose you have a 55mm lens on a 350D at f/8. The hyperfocal distance is 20m. With the subject at various distances, the DOF is as follows:

* Subject at 1m: DOF from 0.95m to 1.05m (48% in front)
* Subject at 2m: DOF from 1.82m to 2.22m (45% in front)
* Subject at 3m: DOF from 2.61m to 3.52m (43% in front)
* Subject at 5m: DOF from 4m to 6.65m (38% in front)
* Subject at 6.67m: DOF from 5m to 10m (33% in front)
* Subject at 10m: DOF from 6.67m to 20m (25% in front)
* Subject at 15m: DOF from 8.57m to 60.2m (12% in front)
* Subject at 19m: DOF from 9.73m to 395.4m (2% in front)

Note that there is only one point at which the DOF is 1/3 in front of the subject and 2/3 behind the subject, and that is when the subject is at exactly 1/3 of the hyperfocal distance.

Note also that the maximum DOF is achieved when the subject is at the hyperfocal distance.

My recommendation for landscape photography: focus just beyond the hyperfocal distance. The trouble with hyperfocal focussing is that, by definition, objects at infinity are right on the limit of acceptable sharpness. However, "acceptable" is a somewhat flexible term and what's acceptably sharp on a computer monitor might not be acceptably sharp on a 36"x24" print. So if there are objects in the scene "at infinity" (i.e. a long way away), then it's probably safest to err on the side of caution by focussing on a point somewhat beyond the hyperfocal distance.
 
Adam, probably not. If your subject is at 5m you want to focus on your subject, do you not? If you want your subject to be in focus and also the background, way into the distance then you want to set up a focal length and aperture that keeps something at 5m within the DOF and also keeps the horizon sharp. You will actually want to set focus a little bit behind your subject, not in front....... unless there is something in front of the subject that you also want sharp.

It would be better if you explain what you wish to accomplish and then we can perhaps suggest a solution. You seem to have picked up on hyperfocal distance as an approach but I'm not sure whether that is what you are needing.

Here is an example from the DOF calculator. I've chosen values for focal length and aperture that will give you a subject at 5m that is sharp and also the background right to the far horizon and beyond. The hyperfocal distance is 8.09m but even something as close as 4.05m will be sharp, including your subject which is at 5m. You will want to focus at 8.09m, behind your subject, not in front of it.

MWSnap%202008-08-03%2C%2022_06_32.jpg


The real question to be answered is...... assuming you have a foreground, a subject and a background, how much of each do you want to be in focus?
 
The way I understand things

Hyperfocal distance is the point you focus on to ensure that the maximum amount of the scene is in focus. At this distance everything from 1/2 the distance to infintiy will be in "acceptable" sharpness.

This point changes with sensor size, focal length and aperture but can be calculated quite easily using online calculators. e.g. This one
 
Adamgilbert said:
so subject is 5meters away, i'm meant to focus 38% in front?
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No.

If you focus on a subject 5m away, the area which is in focus (using this lens, at this aperture, on this camera) extends from 4m away to 6.65m away. So 38% of the in-focus range is in front of the subject and 62% of it is behind the subject.
 
Basically shot a landscape and the pavement at the front of the image was abit fuzy and my tutor picked up on it, but never mentioned how to fix it but mentioned hyper focal distance, i just cant seem to get the hang of it.
 
When you focus on something at a particular distance there will be an area a bit closer than that distance which will also look sharp and an area beyond your focus point that will also look sharp. This area is called the Depth Of Field (DOF). The DOF varies depending upon a number of factors, and the online DOF calculator lets you play around with these factors to figure out how DOF works. As well as giving you some hard numbers it also generates a little diagram that shows you what is going on.

For any given camera body (sensor size) the DOF varies as follows....

- The greater the distance to your focus point (normally your subject) the greater your DOF;

- The smaller your aperture (larger f/ number) the greater your DOF;

- The shorter your focal length, the greater your DOF.

The hyperfocal distance is the focus distance that keeps things in focus as close as possible while also keeping the farthest points (horizon, sun, moon, stars etc) also sharp. If you want something very close to be in focus as well as the horizon then you will need a small aperture and also a wideish angle for your focal length.

Here's an example showing a large DOF. The lens was at 17mm, so pretty wide angle, and the aperture was f/8. I can't remember exactly where I set the focus but it was probably somewhere around the edge of the paving leading onto the beach.

20071202_153459_0616_LR.jpg


Plugging in those numbers into the DOF calculator I see the hyperfocal distance is 1.92m and I could actually have everything in focus from just 1m away all the way to the horizon. I probably focused a bit farther away than I needed to but it has not caused a problem.

Here's an even more extreme example, at 10mm and f/8. Hyperfocal distance with this combination is 67cm with a DOF extending from just 30cm to infinity. It is also worth noting that there is not a sudden drop off in sharpness beyond either end of the DOF, it's just that things gradually become increasingly soft. The only thing that is truly sharp is the bit you focus on, but the DOF is an area which is "acceptably sharp". There is no hard and fast rule on what is "acceptably sharp" and the smaller you display the image the larger your DOF will actually seem to be, because you are shrinking the image and concealing the softness.

20071128_160025_0373_LR.jpg


One final point to consider is the effect of post processing and sharpening on the final appearance of your image. I have long known that you should make sharpening your very final step after resizing, but have only recently started to apply that knowledge to my images. It makes a big difference.
 
Here's a link to create your own set of charts, I carry mine around with me...

http://www.dofmaster.com/charts.html


However,

I don't always use hyperfocal...I only use it if the foreground is very close, say within 2 feet, the rest of the time I use F11 - F16 & focus on the most important distant feature I want to appear sharp, works for me anyway :thumbs:


simon
 
However, "acceptable" is a somewhat flexible term
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Yes it should really say crap...soft...or rubbish

the pavement at the front of the image was abit fuzy and my tutor picked up on it, but never mentioned how to fix it
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Make a note and ask him how, thats his job.

Ive had more success focussing at infinity (furthest point in frame) possible and then retrieving near focus by reducing the aperture.

Using the hyperfocal focussing method...17mm at 9 or 12ft @ f8 resulted in a very soft infinity

See this LINK

and HERE
 
On the subject of DoF I've also heard the term depth of focus. Is this just another term for depth of field, or something different? If the latter, can anyone explain?
 
parish said:
On the subject of DoF I've also heard the term depth of focus. Is this just another term for depth of field, or something different? If the latter, can anyone explain?
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AFAIK they are the same thing.
 
There is only one sharp area when focussing a lens, that is the actual point of focus. From thereon in it is a matter of what we decide ourselves to be an acceptable level of sharpness. This 'band' of focus you can move nearer to the camera to incorporate a sharper foreground, or further away to make the background sharper. The 'hyperfocal distance' sharpens the foreground considerably (which is arguably where sharpness is most wanted), but I find leaves the background soft - unacceptably so for me personally.
My suggestion is to take several photos of perhaps cars in the street with the focus set at 20m; 15m; 10m; 5m and whatever the 'hyperfocal distance' shows. Use f11 or f16 as your aperture. Examine the results on the pc (maybe at 100% in Photoshop), look at the sharpness of the foreground; middle distance and background and select for future use that which is acceptable to you. The distance chosen will no doubt be different for everyone as what I deem an acceptable zone of sharpness, you may not.
This should at least resolve the issue of focussing 1/3 into the picture vs hyperfocal distance.
I personally do not like the 'hyperfocal distance.'
 
foodpoison said:
Take three shots at three different focus points.
Pick the best one and then have a beer.

A lot nicer than trying to understand this hyperfocus malarcky :p
Click to expand...

:clap: That's pretty much my style also! :D
 
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