How to Focus ⅓ Into a Photo for Deep Depth-of-Field

In Photo Basics by Frank Gallagher9 Comments

 

If you’re a landscape photographer, you’ve probably had someone tell you to focus 1/3 of the way into the scene.  It’s one of the many guidelines about photography that have sprung up over time.  Like most guidelines, it doesn’t cover every situation and it’s open to interpretation.  But, a lot of the time it works!

 

In this article, we’ll explore what it means, where it came from, when it works and when it doesn’t, and whether digital technologies have made this technique obsolete.

 

What does it mean?

If you focus your camera 1/3 of the way into the scene, does that mean using the rule of thirds, 1/3 of the distance to the farthest object in the frame, 1/3 of the way from the top or bottom of the image, or something else?  And does it involve math?

 

In landscape photography, you’re often using wide angel lenses at medium to small apertures, trying to get everything tack sharp, from the foreground element that draws you into the scene and provides depth and scale to the distant objects that may be miles away.

 

Ansel Adams and other well-known photographers recommended placing the focus point about 1/3 of the way between the nearest object that you want to have in focus and the farthest object you want in focus.  In practice, this often can be approximated by placing your focus 1/3 of the way up from the bottom of the image.  This guideline can be handy when you’re trying to get the foreground, middle ground and far distance to all be sharp, but don’t have a lot of time to get the shot.  Maybe you’re chasing some great, but fleeting, light.  Or you’re trying to get a moving animal in its natural surroundings and you want maximize the zone of sharpness in your image.  Focusing 1/3 of the way up the frame gives you the best chance to get a great image in a hurry.

 

 

This won’t work all the time, so use it thoughtfully.  You may want to emphasize a foreground object and don’t care as much about the distant surroundings.  You may want a very shallow range of focus to isolate your subject against a blurred background.  And there are photographers who argue that you should focus at infinity for maximum sharpness across the largest area of a shot.  But, if you’re out in the field and moving fast, it’s a great little trick to know!

 

Where does it come from?

You can only really achieve perfect focus at one spot, or on a plane in which each element will be very well focused.  Objects slightly in front of or slightly behind the plane of focus will be a tiny bit less sharp.  The farther an object is from the plane of focus, the more degraded the sharpness becomes.  At some distance from the plane of focus, objects cease being acceptably sharp and become noticeably blurry.  The physics of light and lenses dictate that this zone of acceptable sharpness extends farther behind the plane of focus than in front of it.

 

The “focus 1/3 of the way into the scene” guideline was developed decades ago to help photographers maximize the depth of field in any given shot.  There are many complicated and technical definitions of depth of field but, for our purposes, it is the zone in front of and behind the point on which you focus (the plane of focus) where details are rendered acceptably sharp.  It’s determined by your lens size, the aperture you select, and the distance your subject is from your camera.  You can learn more about depth of field here. We just need to know that, if you can figure out the right combination of lens, aperture and distance, you can get everything you want in reasonably sharp focus.

 

And that’s where the math comes in.  There are formulas to figure this all out but, you can put away those calculators: there’s no math involved in this article.  Whew!  I can hear the collective sigh of relief.  You can easily google enough depth of field equations to satisfy even the biggest photography math nerd.  We just don’t need it for this discussion.

 

Older lenses, and some new wide angles lenses, have these scales engraved in the barrel.

 

 

I typically use the data in the PhotoPills app on my phone when I need to check depth of field, but there are many other sources.  In this PhotoPills chart, for example, with my 20 mm lens, you can see that, if my main subject is 9 feet away from my camera and I want that to be in very sharp focus, but there’s a neat foreground feature 3 feet away, then by choosing an aperture of f10 or smaller, I can focus on my subject and get everything from the foreground object all the way to infinity in acceptable focus.

 

 

Another way to find the best spot to place your focus that will get you the maximum depth of field is to find the hyperfocal distance.  There’s a lot more math here that we can also ignore.  Yay!  You can learn more about hyperfocal distance here.  What matters is that, if you focus at the hyperfocal distance, everything from ½ that distance to infinity will be in acceptable focus.  So, if you come upon a beautiful scene with a fence that’s two feet away and it provides a great leading line to a lake in the middle ground and a mountain in the distance, the PhotoPills table says you could use an aperture of f/11 and set your focus point at 3’11.”  That will render acceptably sharp everything from about 2’ (1/2 the 3’11” hyperfocal distance) to infinity.

 

 

You’re probably not going to be out in the field with a tape measure or a laser rangefinder so be aware that a relatively small error that places your focus point closer to the camera than what’s in the tables can potentially have a significant blurring effect on objects at infinity.  If I focus my 20mm lens with an f/8 aperture at six feet, I get everything from three feet to infinity in acceptable focus.  If I mistakenly focus on an object that’s really five feet away, my depth of field goes from about 2 ½ feet to just over 50 feet—quite a dramatic change!  Focusing 1/3 of the way up from the bottom of the frame will often eliminate this underestimation of focus issue.  It’s better to focus a little farther in than to focus a little too close.

 

And, as it happens, using either depth of field or hyperfocal distance, you usually seem to wind up placing your focus point about 1/3 of the way up the frame anyway.  But it doesn’t always work.

 

When does it work and when doesn’t it?

As mentioned earlier, this technique works well for landscapes where you want to achieve maximum depth of field and are using a wide angle lens.  You will probably be using a medium to small aperture–f/8, f/11, f/16.  Large apertures like f/2.8 don’t offer enough depth of field, which is why they are typically used to get a subject in sharp focus while the surroundings are a soft blur or at night when you need the extra light-gathering capabilities of a wide-open lens.

 

Likewise, telephoto lenses don’t offer much depth of field until you are focusing way out in the distance.  My 70-200 lens at f/8 has a hyperfocal distance of almost 70 feet at 70 mm, meaning items from about 35 feet to infinity will be in focus.  At 200 mm, it’s almost 550 feet, meaning objects from 275 feet to infinity would be in focus.

 

And there will be situations where you can’t get the right combination of lens, aperture and shutter speed to achieve good depth of field.  The light could be fading and you can’t use a high enough ISO to compensate.  It might be windy and you need to use a really fast shutter speed to freeze movement.

 

 

In a situation like this waterfall, where do you focus?  The rock on the left, or the one on the right, or the small one in the center?  Each is a different distance from the camera but they're all 1/3 of the way up the frame.  Here, the more important thing is to get that foreground rock on the left tack sharp, so I'll focus there.  With scenes like this, I'll favor the foreground over the rest of the shot, knowing my wide angle lens has enough depth of field to get the rest acceptably sharp.

 

There will also be times when the most important object in the photo isn’t near or far and isn’t located 1/3 of the way up from the bottom of image.  In those cases, focus on the most important object!  You don’t want the eyes of the wolf in the middle of your image to be slightly blurry while the uninteresting blades of grass 1/3 of the way in are crisp and focused.

 

Then there could also be times when the far distant object is more important than the foreground object.  Perhaps there’s not much detail in the foreground item while there is important detail in the distant mountain.  The 1/3 into the frame method and the hyperfocal distance tables privilege a sharp foreground over a sharp background.  To the human eye, mountains in the distance look somewhat less sharp than a nearby object, so this makes sense.  But there may be times you want to really emphasize the distant object.

 

You might be shooting a scene with a big, tall foreground object where focusing 1/3 of the way up is still focusing on your closest foreground object.  There are lots of occasions where this won’t work, but many, many more where it will.

 

Focusing near or far?  Merklinger’s approach

Landscape photographer Thomas Heaton recently posted a You Tube video, “Where did I Focus,” in which he tried focusing at infinity and ended up preferring that to hyperfocal distance or focusing 1/3 of the way in.  That got me curious, which led to some research, which finally led me to Harold M. Merklinger.

 

Back in 1990, Merklinger published “The Ins and Outs of Focus: an Alternative Way to Estimate Depth of Field and Sharpness in the Photographic Image,” a different way to calculate where to focus to get maximum depth of field (and there’s tons of mathematics in it, for you math fans).  He felt that traditional depth of field tables and the idea of focusing 1/3 of the way into a scene left something to be desired.  First, the far background was often unacceptably (to him) blurry while the foreground was unnaturally sharp.  Second, those rules and calculations failed to take into consideration any of the characteristics of the foreground element.  How big was it?  How detailed was it?  How much detail did you need to record to keep it recognizable?

Instead, Merklinger advocated focusing at infinity and then dividing the focal length of the lens by the aperture to get the minimum object size (in mm) that could be acceptably resolved from infinity to right in front of the camera.  So, if my 20 mm lens is set at f/10 and focused at infinity, I divide 20 by 10 and get 2.  So any object greater than 2 mm should have adequate resolution from one inch away from my camera to one mile to infinity.  It may not be perfectly sharp, but it would be identifiable, and how much detail do you need in a 3 or 4 mm wide blade of grass in the foreground anyway?

 

With the traditional methods, you get a very sharp foreground and a background that’s at the limits of acceptable sharpness.  With Merklinger’s method, you get a very sharp middle ground and background and a foreground that may be at the limits of acceptable sharpness.

 

Is this still useful or are there digital alternatives

Using Live View on your camera can give you a very good sense of what’s in focus as you zoom in and move around, but you have to focus somewhere first.  And your screen has to have enough resolution for you to really see the sharpness.

 

Focus stacking is one of the modern alternatives for getting maximum depth of field.  In this technique, you take multiple shots of the exact same scene focusing progressively deeper into the scene with each shot.  Then the exposures are blended together in post processing using Photoshop, Helicon Focus or Zerene Stacker for example.  Rusty Parkhurst wrote a great description of focus stacking here and there’s a five-part video tutorial on Improve Photography Plus.

 

You run into problems with focus stacking when there is a lot of movement in the scene.  Crashing waves, blowing leaves, moving people, changing light and shadows—any of these will cause problems when blending exposures.  And there will be situations where you aren’t shooting from a tripod or just don’t have the time to carefully shoot a focus stack of images.

 

So, what do I do?

 

 

With an average landscape shot, I’ll get my composition, set my camera and tripod up and then focus 1/3 of the way up from the bottom of the screen.  I’ll turn on Live View and zoom in to check the foreground focus and then zoom to check the distant background focus.  If one is in sharp focus but the other isn’t, I’ll try tweaking the focus a bit.  If that doesn’t work, I’ll decrease the aperture and try again.  If that doesn’t work either, then I’ll pull out my phone and check PhotoPills tables for depth of field and hyperfocal distance.  If it seems I’m pushing the limits of sharpness and the situation is right, I’ll try focus stacking.

 

If, however, I’m hand holding and it’s windy or I’m shooting from the back of moving vehicle or only have one chance to get the shot, I’ll try to get a fast shutter speed, an aperture of f/11 or so, focus 1/3 or a little more of the way into the scene and press the shutter.  More often than not, it works!


About the Author

Frank Gallagher

Frank Gallagher is a full-time photographer who lives in the Washington, DC area, specializing in working with nonprofit organizations. In addition to writing about photography, he is one of the leaders of the DC-area NANPA Nature Photography Meetup group and manages the NANPA blog, as well as edits their annual Expressions magazine. He enjoys landscape and wildlife photography, travel and spending time with his wife exploring new places and rediscovering old ones.

Comments

  1. My Fuji X-T2 has a depth of field distance indicator at the bottom of the screen that is so good I have stopped using autofocus and use manual combined with the depth of field line and focus peaking for the last year. It’s a wonderful guide for getting exactly the shot I want to get.

    1. @Mark – All the info that mirrorless cameras can give in the viewfinder is REALLY useful. That’s why I believe the DSLR’s days are numbered now.

    2. @Mark Focus peaking is one of the things us Nikon and Canon shooters envy in the mirrorless crowd!

  2. Mark, many of us are envious of you Fuji users and other photographers with other camera systems that give in-camera feedback on focus and depth of field.

    For this reason, being a Canon guy, and thus able to use Magic Lantern, I wrote a script that provides a focus bar on EOS cameras that run Magic Lantern.

    The focus bar also gives you landscape focus stacking control.

    The focus bar is fully diffraction aware.

    If any Canon user wants to try out the focus bar, they can get it from here: http://photography.grayheron.net/2017/06/focus-bar-update.html

    Cheers

    Garry

      1. @Jim, as a photographer, rather than a video-guy, and a canon user (5D3, EOSM and IR-converted 50D) I’m so glad I have access to Magic Lantern’s capabilities.

        The features I use the most are RAW histograms, RAW-auto-ETTR, Dual-ISO and RAW auto bracketing. But the killer feature is the Lua scripting, that lets me really control the cameras I have, eg auto landscape bracketing with auto exposure bracketing.

        But the script I’m most proud of is the focus bar, especially how it allows me to focus bracket, with no guess work.

        I hope other IP readers try out ML and the focus bar. I’m always looking for feedback and will willingly try out new ideas/suggestions.

        BTW I lived in the US for 8 years, but have been back in the UK now for 2 years. I have religiously listened to IP podcasts from the beginning, and repeatedly. So keep up the good work!

        Cheers

        Garry
        photography.grayheron.net

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