Have you ever came home after a great day of photography, only to upload your images and find that they had great photo compositions, but the focus was not quite right – making them unusable?
By applying the simple rules of Hyperfocal Distance you can be sure that you are shooting images which are sharp from foreground to background on almost every occasion.
I will be using an image that I took recently of Castlerigg Stone Circle to show you how you can put these simple rules into practice so that you can obtain maximum depth of field (DOF) in all your landscape photo compositions.
The hyperfocal distance is the point at which you should focus your lens to allow you to get maximum DOF. Once you’ve focused on this point, everything from half the hyperfocal distance to infinity will be sharp. This means that if you’re focused at a hyperfocal distance of 10 metres then, five metres to infinity will be sharp.If you simply focus on the subject itself, then only one-third of the area in front of that subject and two-thirds of the area behind it will be sharp.
A simple cheat that will work most of the time, is to focus one third of the way into the scene. Whilst this works up to a point, to obtain maximum depth of field, you will need to calculate the hyperfocal distance correctly!
So let’s imagine for a moment that I knew nothing about hyperfocal distance rules. I would set my camera to aperture priority (AV on most digital SLRs) and to f22 thinking that this f-stop would give me maximum depth of field. Because I would be using a tripod and shutter release, the shutter speed would not really be that relevant as there would be very little chance of camera shake. But I would choose a low ISO (160) to try to ensure that I got a good crisp image. With my chosen lens, I would set the focal length to 24mm to obtain the widest angle shot that I could to get in most of the stones in the circle. Because the stones are the main subject of the scene, I would focus on the stones in the foreground. The resulting image would appear sharp but diffraction would occur. This is caused when light passes sharp edges or goes through narrow slits deflecting the rays of light to produce fringes of light and dark bands which distort the image. Whilst this will not be noticeable on your LCD and you may think that it looks just fine, it will be more noticeable when the image is viewed at a larger size or printed.
The following images show the results that I would get using the same ISO and focal length but changing my f-stop to f11, which is the optimum f-stop to get maximum depth of field for landscape photography, but focusing on various parts of the scene.
In this image, I focused on the fells in the background. As you can see, the stones in the foreground are out of focus whilst the fells and a third of the distance from the fells backwards towards the camera are sharp and in focus.
In this image, I focused on the stones in the middle ground. Here the stones nearest to the camera are slightly out of focus, the stones in the middle ground and the fells in the background are sharp and in focus.
I will now let you into the simple secret which will correct all the above focusing problems and allow you to obtain the maximum depth of field in your landscape images. Let’s start with the formula for calculating hyperfocal distance. Don’t worry about it; it’s much less complicated than it looks!
Focal length – This will, of course, be different for every image that you take. For my shot of Castlerigg Stone Circle I used my 24 to 105mm lens at its widest focal length i.e. 24mm. This value can be read off from the top of your lens barrel once you are happy with your composition. For fixed length lenses just use the fixed focal length of your prime lens.
Circle of confusion – All you need to know here is that this constant differs depending on the type of camera that you are using and is based on what is considered to be acceptable sharpness in an 8″ x10″ print seen at normal viewing distance. The most popular values are as follows:-
Digital SLR = 0.02
35mm format and digital SLR full-frame = 0.03
6x6cm format = 0.06
4x5in format = 0.15
F-stop – The optimum f-number for landscape photography is considered to be either f11 or f13. My preferred f-stop is f11 as I find that this gives you the maximum depth of field without any diffraction occurring.
Using the above formula, the hyperfocal distance for my shot was calculated as follows:-
Therefore, the hyperfocal distance is approximately 1.8 metres.
Once you have calculated this figure, you now know the distance from your tripod that you need to focus on to obtain maximum depth of field. Without re-composing your photograph, you now need to identify an object which is that distance away from your tripod and set the focusing point on your camera on this object. Your camera will have a number of focusing points displayed on its LCD and you need to make active the focusing point that is covering this object. Again, you need to consult your camera’s manual if you are unsure how to make this focusing point active. Everything from this focusing point (i.e. the hyperfocal distance) to infinity and half way between this focusing point and the tripod will now be sharp and in focus. If you are unable to make a focusing point active on an object then switch your lens to manual focus and focus on the object manually.
In this image, I focused on the hyperfocal distance point of 1.8 metres which I estimated to be on the two stones in the left foreground. As you can see, the result is an image which is crisp and sharp from front to back. Also, half the distance between the hyperfocal point and the tripod (approx 0.9 of a metre) would also be pin sharp.
OK, so calculating the hyperfocal distance is a bit more effort and you may need to carry a calculator around when you first start to use this technique. But providing that you stick to either f11 or f13 for your landscapes, you will soon remember the different hyperfocal distances for the lenses and focal lengths that you normally shoot at. To help you, I have set out two tables below which show the hyperfocal distances at various focal lengths for the most commonly used cameras. All you need to know is the focal length multiplier i.e. crop factor of your camera and choose the appropriate table. Your manual will help you here. Cut out the appropriate table, laminate it and put it into your gear bag. Believe me; you will be truly amazed at the results that you will you get from making such a small effort.
Table 1 – Hyperfocal Distance Calculator for Digital SLR Cameras with a Focal Length Multiplier of 1.6
Table 2 – Hyperfocal Distance Calculator for 35mm and Full Frame Digital SLR Cameras with no Focal Length Multiplier