Landscape photography & Hyperfocal Distances
An essential aspect of landscape photography is getting the whole of the frame acceptably sharp. However when we focus on a point, let’s say a tree or a rock or a blade of grass, it becomes a focusing plane parallel to the sensor with everything in the foreground and the background becoming out of focus. However there is a limited window of distance both in the foreground and the background where the frame remains acceptably sharp. This is the Depth of Field. As a landscape photographer it is imperative to know how to attain that sweet spot of perfect distance that allows you to maximize the Depth of Field for your shots. That sweet spot is called hyperfocal distance. When focus at the hyperfocal distance everything between halfway that distance and infinity will be sharp
Factors on which the Depth of Field depends
The Depth of Field is depended on a combination of a few factors such as aperture, focal length and the focal point (the distance between the subject of focus and the camera). Greater the focal length less is the extent of the frame that is in sharp focus. If you’re using a wide angle lens fully zoomed out, your Depth of Field will be bigger compared to if you’re using a telephoto lens fully zoomed in.
Additionally smaller the aperture, bigger is the Depth of Field and vice versa. When selecting the Aperture Value care should be taken as to what is the optimum aperture at which the image is the sharpest without necessarily getting affected by lens diffraction.
The final factor which affects hyperfocal distance is the focal point, which in turn depends on the combination of focal length and aperture that you’re using. More is the distance between focal point and the camera; more is the Depth of Field. Rule of thumb states that, you should focus roughly 1/3 of the way into your scene in order to achieve maximum DOF. Though, it is rarely optimal; but sometimes helpful.
There is one more aspect that controls the Depth of Field and this is something that once you buy a camera you cannot really do anything about and that is the size of the sensor. As a rule the Depth of Field is inversely proportional to the size of your digital camera’s sensor.
There is however one way in which it is possible to make the whole of the frame acceptably sharp and this is by focusing at the hyperfocal distance.
How to calculate Hyperfocal distance
Hyperfocal distance is always considered together with the given Aperture Value and the focal point. This DOF is usually from half the distance from the focusing point to infinity. There are charts available, ready to use, which gives the approximate hyperfocal distance for a lens of specific focal length set at a specific aperture.
In absolute formula terms Hyperfocal distance or ‘H’ in mm is equal to the square of ‘f’ or the Focal length in mm, divided by the product of ‘N’ which is the f-stop and ‘c’ which is the circle of confusion in mm plus ‘f’.
In real life when shooting out in the open it can be a difficult formula to calculate and then use. As such it is better to know in advance what is the hyperfocal distance and focusing just beyond that so that everything from half the focal point to infinity is acceptably sharp.