Simplifying Hyperfocal Distance

In landscape photography, the issue of focus and the related issue of depth of field lead inexorably towards trying to get to grips with hyperfocal distance. In this article I am simplifying hyperfocal distance so that the principle can be easily used by landscape photographers to get sharp focus front to back.

It’s not what you thought..

Hyperfocal Distance
/ˌhʌɪpəˈfəʊk(ə)l/
noun

the distance between a camera lens and the closest object which is in focus when the lens is focused at infinity.

Oxford English Dictionary

also

hyperfocal distance may refer to the closest distance that a lens can be focused for a given aperture while objects at a distance (infinity) will remain acceptably sharp.

Todd Vorenkamp B&H Photo

and

The hyperfocal distance is defined as the focus distance which places the furthest edge of a depth of field at infinity.

Cambridge in Colour

Simplifying Hyperfocal Distance

Simplifying hyperfocal distance? Confused? You’re not alone. I laboured for years with the simple belief that hyperfocal distance was the point to focus on, found roughly 1/3 of the way into a composition. The presence of Maths should have alerted me to the danger of such a broad definition. There are rules of thumb that will work some of the time but not all and I’ll go into a few of these later.

But first let’s get one thing straight with the intention of simplifying hyperfocal distance.

The hyperfocal distance varies according to what lens you are using, what sensor and something (appropriately) called the Circle of Confusion. You’ll be relieved to know that the Circle of Confusion for full frame cameras is the same. 0.03mm

Hyperfocal Distance is defined as the focal length squared, divided by Aperture x Circle of Confusion.

So that’s the maths. What does it mean in real life?

Well, you’ll already have noticed that wide angle lenses have greater depth of field than telephoto lenses. Think of that extended foreground. This makes a mockery of the “focus one third of the way into the picture” Rule.

What we know for certain is that all lenses have at any given aperture, a field of sharp focus in which objects will be rendered as acceptably sharp.

N.B. Acceptably sharp is not the same as pin sharp !

It is this that causes landscape photographers so much grief. We want to see everything pin sharp!

To achieve pin sharpness it is necessary to focus stack. On location, we don’t measure to the centimetre the distance of the point of focus from the camera. If it happens to coincide with the Hyperfocal Distance then happy days, we ‘should’ get sharpness front to back. If we get this wrong, we may lose sharpness at the back of the image or at the front.

Rules of Thumb

Using the PhotoPills app, I can get some precise readings for my lens/camera combinations. And this gives a flavour of why it is useful to know about these things.

Using my Canon EOS 5DS with a 50mm lens at f/11 with a subject 5 metres away gives me a total depth of field of 12.31m with a hyperfocal near limit of 3.7m and a far limit of 15.29m. Hyperfocal distance is 7.4m. I could, by focusing in front of the subject, bring the near point closer at the expense of something in the distance. But the relationship between the in front focus and the beyond focus is fixed according to the focal length,

Using the same camera with a 100mm lens at f/11 with a subject 30 metres away gives me a different set of figures. Total depth of field of infinity, hyperfocal near limit of 14.76m and a far limit of infinity. Hyperfocal distance is 29.52m Now this gets interesting because once we hit infinity, the near limit stays the same. So in theory you can focus anywhere between the back of the frame and 29.52m and get the same result. Acceptably sharp from 14.76m to infinity. To all intents and purposes, if I focus on the subject, I’ll get acceptable front to back focus.

Using the same camera with a 300mm lens at f/11 with a subject 300m away gives me another different set of figures. Near limit is still 132.53m and far limit is infinity. Hyperfocal distance is 265.06m. To all intents and purposes, if I focus on the subject, I’ll get acceptable front to back focus.

So where does this leave rules of thumb? They more or less work at typically sharp apertures f/8, f/11. Remember small apertures like f/22 create soft images because of diffusion. Always work in the range of sharpness, which will vary with every lens. Use DxOMark to look up the figures.

The Rule of 30%

If the scene does not extend to the horizon and has little or no foreground, then hyperfocal distance is irrelevant. Rule of 30% works in these circumstances.

You can see from the figures above though that the Rule of 30% is not accurate for landscape photography.

Double the Distance

This rule will deliver equal or acceptable sharpness front to back. The rule says that you focus at double the distance from the nearest thing in your image. Check the figures above, this is more or less hyperfocal distance. But remember, it will not deliver pin sharpness.

A few more helpful hints –

• For distant landscapes extending to the horizon, use f/8 eg. picking detail out of the scene.
• For landscapes with a wide lens and more of a foreground, use f/11 – classic wide angle portrait shot with flower or rock in the foreground
• For landscapes with a very nearby foreground, or when you’re using a telephoto lens, use up to f/16 no more. If this fails, read on…

How to get Pin Sharpness

I’ve written about this before, check out my guide – Ultimate Guide to Taking Sharp Landscape Photographs. Apart from the techniques there, which are mostly concerned with the camera, the only way to ensure pin sharpness in a landscape extending to the horizon, is focus stacking.

In principle, this is how it works. Use f/8 or f/11 Aperture.

Focus on infinity and then adjust focus closer until the point where the farthest thing that you want to be pin sharp in your picture is exactly in focus. Take a frame.

Focus on the nearest thing you want to be exactly in focus in your picture and take a frame.

In principle, the realm of sharp focus in these two images will overlap meaning you can blend the images in Lightroom or Photoshop to deliver a final, blended shot. You may want a third shot in the middle somewhere if you need it.

Simplifying Hyperfocal Distance – Conclusion

Hyperfocal distance is not simple, but it’s a great way to help move from a cloudy understanding that lenses are different and aperture moves the depth of field to something a little more scientific. It’s not essential to do the maths or even to use PhotoPills, (though that is the most useful app for landscape photography!)

Next week I will be doing an article and a video, about lens calibration – sharpness, hyperfocal distance and depth of field are joined at the hip, so it’s essential that your lenses are properly calibrated. I will go through the process of doing it manually and with software.