Landscape Photography Basics: Part Two – Depth Of Field

The last post about landscape photography basics explored a little about something frequently used: wide angle lenses. Another aspect of landscapes is that they often have a greater depth of field compared to portraits, macro, or wild life photographs.

Greater Depth of Field

What the heck does that mean? Usually you are trying to capture a larger scene; a beach, a canyon, a valley, a forest, etc. You are probably trying to capture the experience of being there. Consider what the human eye does in these experiences. You scan the scene. Your eyes will focus on a subject, move, focus on another subject, move, refocus, and so on. Not only that but your pupils dilate and contract to accommodate the different light in the same scene.

Bodega Head, northern California. Canon 5d Mk III, 17mm, f/16

To achieve this with your camera you select an aperture that will result in as much of the scene (front to back) in focus as you want. Usually this means an aperture ranging from f/8 to something less than the maximum (that’s usually around f/22).

Right about now you may be wrinkling up your nose thinking…

f slash a number? What the heck does that mean?

That’s a perfectly natural response. For a good beginner-level discussion on the topic read this article on The Exposure Triangle . I’ll summarize it like this:

    • A lower number is a wider opening in the lens
    • A higher number is a smaller opening
Wide open at f/2.8
A tiny aperture at f/22
Example wide aperture around f/4
Example middle aperture around f/8
Example small aperture around f/13

A larger aperture (wider opening: f/1.8 to 4.0):

  • Allows in more light
  • Allows for shorter exposure times

The depth of field is shallow (less in front of and beyond your subject will be in focus). This can be great for isolating your subject by making the background blurry while the subject is in sharp focus. Here is a series of examples shot with a Canon 50mm prime f/1.8 using a Canon 7d Mk II. Each image uses an increasingly small aperture. Notice that each takes a little longer to expose, starting at 1/40 of a second at f/1.8 and ending at 1.6 seconds at f/16

f/1.8. The candle is in focus but everything in front and behind is blurry. Exposure time was 1/40th second
f/2.5: the candle is in focus and the Frankenstein head is a little less blurry.
f/3.5. A little bit more of Frank is coming into focus

A smaller aperture (smaller opening: f/5.6 to f/22 or more):

    • Allows in less light
    • Needs longer exposure times
    • The depth of field is greater (more stuff in front of and behind your subject will be in focus)
f/5.0: the candle and Frank are in focus. The clock in background is taking shape.
f/7.1: the candle and Frank are in tight focus. The clock is still blurry.
f/10: Everything is in focus now. The exposure time was .8 seconds.
f/16: Everything is in focus, but there’s not a lot of value added beyond the clock. The exposure time was 1.6 seconds.

Practical limitations – Chromatic aberration

There are practical limitations that vary depending on lens quality.
Most consumer/hobbyist lenses are optimized for around f/8. Wide open apertures (f/1.4, 2.8, 3.2..) will result in green and purple fringing around edges especially in high contrast areas. This is “chromatic aberration” and drives me kind of bananas personally. Some software is great at compensating for this.

An example of chromatic aberration. Look for the green fringe in the high contrast areas.

Practical limitations -lens diffraction

Very small apertures (f/18, f/20, f/22…) often have the counterintuitive effect of photos that are less sharp. This is called lens diffraction. A complete discussion is outside the scope of my article … and honestly I struggle to describe it particularly well. Dan Mitchell does a great job of explaining what’s going on while debunking a common digital photography myth. I refer to photographer friends often especially when they’re right.

Below is an example of a photo where I made several mistakes. The focus is softer than I wanted for a couple of reasons. The first is probably because I left the image stabilization engaged on my lens. I’ll explain that later, but don’t do that when you’re using a tripod. The other is that I shot this at f/20 when it wasn’t remotely necessary. f/13 would have done fine and focus suffered because of it.

Is this an example of a photograph that’s “wrong?” Yes and here’s why; I didn’t achieve what I set out to do and the final image needed extensive editing. I liked the result at the time but years later not so much.

A barely edited photo from around Mirror Lake. f/20 at 17mm. Just about every problem described earlier is here and then some.

Take a closer look here too: chromatic aberration. You don’t need to be using a wide open aperture to find this in your photograph. It’ll be there in high contrast areas at just about any aperture, but it’ll be most obvious when wide open.

Detail of focus and chromatic aberration problems

Thanks again for reading. I hope it was helpful. Come back for more when I discuss ISO and qualities of light. If you liked what you read then please share with your friends. I love comments and try to respond.