- March 13th, 2011
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Seems like a simple topic. But focus point and depth of field are the first questions that a landscape photographer will wrestle with while setting up for each and every shot. Since it’s something that is considered that often, maybe we should talk a little about it.
Most lenses are at their sharpest around f8.0-f11. There’s always some exception, but that is the normal ‘sweet spot’ that we try to stay close to. If everything that we wanted to shoot was at the same relative distance from the camera, then we could just set it to f8 and shoot away.
The most interesting shots, however, are probably going to have a foreground, a middle ground and a background. Some of my favorite shots have a foreground that is just inches away from the camera lens and a background that extends to infinity. How do you solve that problem? That’s the real question for this discussion.
I’m going to suggest 2 solutions:
1. Using the principles of Hyperfocal Distance, set the Aperture so that the whole scene is in focus.
Every Aperture/Focal Length setting on a lens has a specific ‘Hyperfocal Distance’ point. It sounds complicate but its just simple physics (remember that class?). Hyperfocal Distance is the point of focus at a specific Aperture/Focal Length setting that will maximise the depth of field. How do you find the Hyperfocal Distance? Use this handy calculator: Hyperfocal Calculator. Make changes to the Aperture and the Focal Length and see what happens to the Hyperfocal Distance point.
When looking at your scene through the view-finder, your point of focus will need to be twice the distance of your nearest object that you need in focus. In other words, if your near-field is at 5 feet and your background extends to infinity, determine your settings required with a focal point at 10 feet (twice the near-field). To be safe I normally add an additional one-third to a full stop of Aperture.
I also carry a little laminated card that I’ve printed up with a chart of various Hyperfocal Distances for various Aperture/Focal Length combinations. It’s a rather low-tech system, but a good reference when I don’t have a computer handy.
This chart is based on a full-frame camera. Feel free to print it for your own reference.
Most DSLR’s have an Aperture ‘preview’ button somewhere near where the lens attaches to the camera body. While looking through the viewfinder, push this button and you will see what the image will look like at the current Aperture setting. This will also darken what you are viewing (because you’re allowing less light through your lens), but will be an accurate view of what your depth of field will look like.
2. Focus Bracketing. Shoot 2 identical images, one focused on the near field, and one focused on the distant field. You can then merge these two images in Photoshop to create a single image that has great depth of field.
I still recommend getting it right in a single shot if possible. But if the tiny flowers in the foreground are 10 inches from your lens and the mountains are miles away, you cannot create the depth of fielded needed in a single shot – at least with a normal lens. This is the domain of the tilt/shift lenses. Great lenses, but expensive and not as versatile as a normal zoom. If you have lots of money, they are amazing though – and a topic for a future discussion.
Things to be careful of in this scenario; you should still use a rather small aperture – f11 or f16, in order to get as much in focus as possible. This will make your merge line less obvious.
For the near field shot, you should focus just beyond the nearest point that you want in focus. How far? Just a little less then twice as far as the nearest point. In other words, if your closest flower is 15 inches from your lens, set the focus at about 30 inches.
Most of the time, a landscape photographer wants everything in sharp focus – from front to back. Those crystal clear gorgeous images that we all love don’t just happen – they are well thought out. Things like time of day, position of the sun, clouds and sky, color temperature, and other factors all combine to make a great photograph.
If everything comes together perfectly, but you miss the focus, then your image will be one that you will always know could have been better. That’s not a good feeling. Nailing the focus is just one step in the process of creating beautiful images, but it’s an important one.