Depth of Field in the Field

Gerry van der Walt All Authors, Gerry 6 Comments

Depth of field is without a doubt one of the most powerful tools you have to change the look and feel of your images but it is also one of the most misunderstood concepts in photography.

Last week we spent a morning in the Mara working on depth of field and how various factors will influence the results you out in the field.  Before I show you the experiment we did let’s quickly touch on the basics.

The depth of field in an image refers to the acceptable level of sharpness in an image.  A shallow depth of field will render a small part of the image in focus with the background being soft and out of focus while a large depth of field will render more of the image, from front to back, in focus.  In our courses and workshops I call this the red zone.  You’ll see why in the images below.

There are four factors that influence the depth of field in an image but before we get there let’s first look at a basic example.

The first thing you need to decide is what part of an image you want as your subject in the frame and place your focus point on that subject.  In the image below the photographer would be aiming at the lion from the right of frame.

Gerry van der Walt - Wildlife Photography

In the above example I locked my focus on the lioness’s eye.

By dialling in a large aperture – remember that this is done by selecting a small f-number – I will have a relatively small depth of field, a small red zone.

Gerry van der Walt - Wildlife Photography

Let’s now assume that everything stays the same and I want a larger red zone I can dial in a smaller aperture – a larger number – which will render more of the image, from front to back, sharp and in focus.

Gerry van der Walt - Wildlife Photography

Pretty simple so far right?

A nice and easy way to remember this is that a small f-number will render a small amount of your frame in focus and that a large f-number will result in a large amount of your frame being in focus.  So, everything inside your red zone will be sharp and in focus with everything outside your red zone being more and more out of focus the further it is away from the focal point.

As mentioned earlier there are four factors that influence your red zone in an image with aperture being one of them.  The other three are:

  • Focal length
  • Distance to subject
  • Distance from subject to background
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During our morning last week we did a practical exercise to show the different results of shooting various focal lengths at different apertures and it was a great way for some of our guests to wrap their head around the concept of depth of field and how they can control this in their image.

We chose a tree, as it would not run away while we were busy, and shot various sequences of images with different focal lengths and different aperture settings.  We did not change the distance to the tree so the only two factors that came into play was our focal length and aperture.  Also notice that since my focal point was always the trunk of the tree that it is rendered sharp and in focus regardless of what the settings were.

The first was a 70-200mm lens set to a focal length of 85mm.

85mm @ f/2.8

Gerry van der Walt - Aperture in Wildlife Photography

Not a bad look to the image with the mountain in the background being just a little soft and out of focus.  If anything the foreground in this image shows a little bit of softness.

85mm @ f/8

Gerry van der Walt - Aperture in Wildlife Photography

Very little if any difference don’t you think?  If you look really closely you might pick up a very tiny bit of extra detail in the back but nothing dramatic.

85mm @ f/18

Gerry van der Walt - Aperture in Wildlife Photography

Again, nothing dramatic when compared to the above two images.

Conclusion:  In this instance the aperture and focal length is not going to make a huge difference to the resulting depth of field.  If I wanted more blur in the background in these images I would have had to move closer to the subject and then take the image.

Next up we did the same exercise with a focal length of 400mm which means we should get more dramatic background blur due to the increased focal length.

400mm @ f/4

Gerry van der Walt - Aperture in Wildlife Photography

At f/4 you can definitely see the shallow depth of field which renders the tree, my focal point, sharp and in focus with the background getting progressively more and more out of focus.

400mm @ f/8

Gerry van der Walt - Aperture in Wildlife Photography

See how the detail in the mountain starts to pop a bit more?  This is the result of using a smaller aperture.

400mm @f/18

Gerry van der Walt - Aperture in Wildlife Photography

And again, with a smaller aperture the red zone, the acceptable zone of sharpness, has been increased and much more of the background is rendered sharp and in focus.

Conclusion:  With a longer focal length of 400mm the resulting depth of field becomes a lot more noticeable giving you more creative options.

For the last round of depth of field testing we did the same exercise with a focal length of 600mm.

600mm @ f/4

Gerry van der Walt - Aperture in Wildlife Photography

The shallow depth of field of the super telephoto renders the background detail very soft and out of focus.

600mm @ f/8

Gerry van der Walt - Aperture in Wildlife Photography

The smaller aperture at f/8 still leaves us with a very out of focus background but there is a subtle increase in the detail in the background.

600mm @ f/18

Gerry van der Walt - Aperture in Wildlife Photography

The background is now a little more in focus, albeit still quite soft, and you can see what is happening in the background.

Conclusion:  A super telephoto will give you the ability to render your background very soft and out of focus leaving your subject crisp and in focus.

So, which one is better you ask?  A shallow depth of field or a nice and large one to render everything in the frame in focus?

There is unfortunately no answer to that question and it is completely up to you as the photographer to decide what the story is that you want to convey in the frame.  If you want the focus purely on your subject then use the tools above to render the background silky smooth.  If you want more detail behind your subject because it adds to the story do what you have to do to create a large red zone.

Here are a few things to keep in mind when working on creating depth of field in your wildlife images:

  • It’s difficult to create a very soft background with a small focal length.  Use these to tell environmental stories.
  • Getting closer – everything else remaining the same – will render the background more out of focus.
  • Don’t forget that you can normally control at least 3 of the variables which allows you the creative freedom to capture any given scene.
  • You don’t always have to shoot at the largest aperture available.  Sometimes a bit more of a red zone will make for a stronger image.
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The best place to learn is out in the field so when you are next out there try this exercise with your own lenses so that you can see the results for yourself.  With a little bit of practise you will get a very good understanding of the variables that you have to play with and also get a feeling for the look and feel that your lenses will give to your images.   We do these kind of things on all of our safaris and workshops so if you are keen to learn with us you know what to do!

One final example of how understanding and applying the variable discussed above can help you create stronger images in the field.

Gerry van der Walt - Wildlife Photography

Shot at f/5.3 on a 300mm lens from about 25 meters.

Good luck, keep shooting and leave me a comment if you have any questions!

Until next time.

About the Author

Gerry van der Walt

I am a private and specialist photographic safari guide, public speaker, co founder of Wild Eye and wildlife photographer. Visit my website at www.gerryvanderwalt.com or follow my journey on Snapchat, Instagram, Twitter and Periscope.  I look forward to changing the way you see the world! Have you checked out The Wildlife Photography Podcast?

 

Comments 6

  1. Barry

    Hi Gerry,

    If you’re trying to get the maximum depth of field, in a landscape shot for example, how do you decide how smaller aperture to use? As you know, the image quality suffers at the smaller apertures so you don’t want to just go to the extremes, I do have a an app (f-stop calculator) that I could use but just wondering if you use something like that or have another technique for deciding?

    Cheers
    Barry

    1. Post
      Author
      Gerry

      Good question Barry. In the past I have used dofmaster.com, which is pretty mush the same thing as the app you mention. I have in time gotten used to what kind of apertures to shoot at for my different lens and camera combos. The apps are very useful for working it out initially but eventually you will start knowing, and feeling, what you should use. I agree totally that you should not necessarily close the aperture down all the way and seldomly go smaller than f/16. I wish I had a hard and fast answer but hope that helps a bit! 🙂

  2. Dee Roeofsz

    Hi Gerry,
    Great article & photo’s to demonstrate. Strangely enough I have been pondering exactly this over the last week. Although I did a battery of short courses with VEGA a few years ago to learn all these things, as an amateur/hobbyist photographer, one tends to quickly forget the principles when not out in the field all the time as you guys are fortunate enough to be.
    This article came at a perfect time as we are off to Kruger on Tuesday for the week, which will hopefully give me ample opportunity to practice & experiment!
    Thanks as always to you & all of your amazing team for such interesting & informative articles on an ongoing basis, I try to soak it all up……….well at least as much as what my old brain will allow 🙂
    Dee

    1. Post
      Author
      Gerry

      Thanks for the comment Dee. Always appreciate the feedback and glad the content we generate helps! Good luck in the Kruger and please feel free to drop us a comment of FB message if there is anything we can help with. 🙂 Travel safe.

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