In last week’s post we talked about the factors that effect depth of field and how to use them to increase and decrease it (let’s face it, mostly decrease, everyone just loves to blur the background those days).
But some times you want to get everything in focus, a typical example is when you are taking a picture of a person in a nice landscape and want both the mountains in the background and the family member in the foreground to be in focus (and even if you don’t take vacation snapshots it’s still common to have some object close to the camera in landscape photos because it makes the photo more interesting).
When faced with such a challenge you can focus on the foreground subject and blur the background, you can focus on the background and blur the subject, you can use the techniques we discussed in the last post to increase depth of field (use a wider lens, stop down the aperture, get farther from the foreground subject) – or you can learn about a useful concept called “hyperfocal distance”.
What is hyperfocal distance and why should I care?
The diagram below shows what happens when you focus close to the camera, the red triangle is the point of focus and the yellow bar is the distance range that is in sharp focus – when you’re focusing close to the camera the in-focus are is small and relatively symmetric (the sharp area before the focus point is the same size as the sharp are after the focus point).
As you focus farther from the camera your in focus area grows, but the area behind the focus point grows more than the area in front of the focus point, in the next diagram you can see that focusing on the person leaves a wide (but not wide enough) are in focus behind the person.
As you focus even farther the are behind the focus point continues to grow until it reaches infinity – that is everything behind the focus point is in focus – that exact focusing distance is called hyperfocal distance.
When focusing to the hyperfocal distance (or behind) the area of sharp focus starts at exactly half the distance between the camera and the point of focus and never ends (everything from halfway to the focus point and farther will be in focus).
In the diagram below you can see that by focusing to the hyperfocal distance you can get both the person and background in focus – by focusing a bit behind the person.
How do I know what the hyperfocal distance is?
The hyperfocal distance is effected by all the factors that effect depth of field:
- Focal length – wider lenses (smaller focal length) makes the hyperfocal distance closer.
- Aperture – smaller aperture (larger f number) makes the hyperfocal distance closer.
- Distance – well, we are trying to calculate the distance.
- Circle of confusion – Smaller sensor makes the hyperfocal distance closer.
Like depth of field there are many on-line calculators as well as calculators for every smartphone platform (actually, most depth of field calculators also tell you the hyperfocal distance).
How can I focus to the hyperfocal distance?
If you have a lens with a distance scale you are in luck, after you get the distance from a calculator switch the lens to manual focus and turn the focus ring until you see you are focused just behind the hyper focal distance using the distance scale.
If you don’t have a distance scale you need to find something that is approximately at the correct distance from you and use that to focus.
Quick Tip: focus a little behind the hyperfocal distance because if you accidently focus a little closer the background will be blurred.
Real life example:
I wanted to take a picture where both the subject near the camera and the background are in focus, I started my depth of field calculator app and entered a focal length of 35mm (my favorite focal length) and an aperture of f/8 (for a nice middle of the road aperture) – The calculator tells me the hyper focal distance is 8.20 meter (or ~27 feet).
Armed with this information I went out to a park just across the street from where I live and took this picture I call “dog looking at path” (if you want to buy prints just e-mail me):
In this picture I used the lamp posts to focus, since the posts are more-or-less evenly spaced they give us a nice way to measure distance – I know the post behind the dog is more than 8.2 meter away so I focus on it, I know the post the dog is tied to is about half way between the post I’m focusing on and the post I’m standing next to (it’s out of frame) so by making sure the post near me is in front of me I know the dog is more than half way between me and the focus point.
If I focus on something that is farther than the hyperfocal distance than everything farther than halfway between me and the focus point will be in focus – so that means both the dog and the background.
To prove the point I took 3 pictures, one focused on the dog, one on the background and one on that second lamp post,
Here are 100% crops from those pictures:
The left part is from the picture focused on the dog, the dog ear is sharp but the background is blurred.
The center is focused on the background, the background is sharp but the dog is soft (look at the darker area of the ear that is so clear in the other pictures).
And finally on the right, the right picture is focused using hyperfocal distance and you can clearly see both the dog and the background are in focus.
That’s it for today, hope that helps the next time you want to photograph something close while keeping something far away in the distance sharp.