About the Book
If you want to intelligently maximize depth of field, especially if you're doing landscape or reportage photography, you might be interested in the hyperfocal technique.
In landscape photography for example, it is quite important to include a foreground in the image to give it depth and increase its impact. However, by focusing to infinity, you will often obtain a blurred foreground, which is not the goal. Hyperfocal will allow you to change that.
What is the hyperfocal distance? Definition
- When the focus is on the hyperfocal distance, the depth of field extends from half that hyperfocal distance to infinity.
- In other words, it is the distance between the camera image and the start of the depth of field when the focus is made on the infinite.
So focusing on the hyperfocal (that is, at a place that is located at this hyperfocal distance) allows you to get the largest possible sharp area in the image.What is she influenced by? How to calculate it?
It is influenced by the focal length (50mm, 100mm, etc…), the aperture you have chosen (f / 2.8, f / 5.6, f / 22, etc…) and what is called the circle of confusion ( which we are not going to worry about for the moment because it is quite complex).
I will not give you the mathematical formula that stings the eyes, because it would be of no use to you. (if you are a mathematician, you can consult the Wikipedia page on hyperfocal)Why does it work like this?
Another thing you need to know to understand is that the depth of field is divided not so uniform in front and back to where you made the development (called "subject" in the continuation of this article). In reality, 1/3 of the area of focus is in front of your subject, and 2/3 behind. And you will see that it will help us a lot to use the hyperfocal.
How to use it concretely?
This is where we have a slight problem: as much on the old optics of the time of film, it was easy to adjust to the hyperfocal thanks to the depth of field markers. As much now, this good habit has been lost, and it therefore seems impossible to obtain it simply without doing a complex mathematical calculation.
This is why it is in my opinion a concept a little less useful in the age of fast autofocus and electronic viewfinders.
But good news, if you want to use it on a recent device, there is a trick.
When you focus at infinity, the hyperfocal distance is actually the sharp point closest to you. How to proceed simply:
- Take a snapshot with infinite focus.
- Look at the result: the sharp point closest to you is the hyperfocal.
- Take the same shot again, focusing on the hyperfocal rather than on the infinite.
- The image is always sharp up to infinity, but in addition you have gained 1/3 of the area of sharpness, between you and this hyperfocal point.
This technique allows you to get a sharp foreground in landscape photos. In practice, we are often content to focus at about 1/3 of the height of the image, which is slightly less efficient but much more intuitive.
Be careful, as the hyperfocal distance is only valid at a focal length and at a given aperture, you will have to repeat the exercise each time you change one of these two parameters, that is to say when you zoom in / out or when you change the aperture!
According to dzofilm.com, if you want to know the hyperfocal more precisely, you will need to calculate it. There are tables allowing to know this distance according to the focal length and the aperture, but it is a bit tedious.
There is also an excellent hyperfocal calculator: impossible to take in the field, but I strongly advise you to test it to better understand ! It's in English but it's very simple : just select your camera, focal length, aperture, and subject distance (don't forget to set in meters). You then get the distance to the start and end of the focus area, as well as the hyperfocal distance.
Personally, I use an app on my phone that lets me know it in a way similar to the calculation below, but it's optional: the simple technique of focusing at 1/3 the height of the l Most of the time, this image will allow you to get crisp shots from infinity to you.
What is quite astonishing is that thanks to this distance, one can obtain completely sharp images even at large aperture. For example, with a 50mm f / 1.8 set to its maximum aperture (f / 1.8 therefore), the hyperfocal is located at around 70m. So if I focus at a distance of 70m, the image will be sharp from infinity to me. Be careful, remember the definition above: everything will be clear provided that the element closest to me visible on the picture is at a distance of at least 35m ( half of the hyperfocal).
These distances seem enormous, but in a more classic case with a 20mm set at f/11, the hyperfocal will only be less than 2 meters ! In this case, it is therefore necessary to focus not on infinity, but at about 2 meters away, so that the image is sharp from infinity at a distance of one meter from you (half hyperfocal, always). Astonishing, no?
I am aware that this concept is slightly complex, but it is useful to know it because it is the theoretical principle which allows you to obtain an astonishing sharpness on the totality of your image, which is sometimes essential, in particular in photo of landscape.
But in the digital age, most optics do not have a distance scale that simply allows you to focus on the hyperfocal, so it's a little more complicated to calculate it precisely.
And quite frankly, I don't recommend that you bother doing that: the easiest way is to focus at 1/3 the height of the image, and that's enough.