Archivesdepth of field

Zooming in… Zooming out

Recently, I taught a one-to-one lesson in person with one of my Learning Journey students and we came across an interesting situation.

To note, I don’t ever use my zoom lens. I have one, but I don’t use it. But this student was using a 70-200mm f/2.8 lens – super common amongst pet photographers!

She had the lens zoomed in to 135-200mm which would also be my recommendation, and had the lens on a crop-factor body. So… suddenly, at 200mm, we have a huge amount of compression, and cropping of the scene.

Now, I’m a BIG fan of compression… but in these woods we’d found a couple of beautiful backlit areas with sparkly bokeh, and while we could get really cool rimlight around Journey, we were missing out on the charm of the location because of the compression of the scene! eg., We were only able to see a really tiny amount of the background because of how much it was ‘pulled toward us’.

But of course… we didn’t want to loose that narrow depth of field by simply zooming out to get more of the scene in in order to see the bokeh. If we did, all the leaves, grasses, and stuff in the foreground and background would be more in-focus, with more detail. Not what we necessarily want!

So I suggested to this student that she play with depth of field here. 


What we did:

I suggested my student zoom her lens OUT. Maybe all the way…. and then move HERSELF toward Journey. By zooming OUT, we have less compression, and more of the scene/background in the photo… but by moving CLOSE to Journey, we narrow up the depth of field again!

Below are the two different photos we got. Journey hasn’t moved, but the student has zoomed out and physically moved herself forward in the 2nd photo.

So this is just a reminder that if you are using a zoom lens, that although zooming all the way in gives you beautiful, soft backgrounds, and lovely compression, you can play with the zoom length and how close you are to the dog to include more of the scene in, if it’s beneficial to do so. 

Don’t feel like you always HAVE to be zoomed in – or you might be missing some pretty bokeh oportunities.

QU: I only have a “kit lens”! Does that mean I can’t get blurry backgrounds?

Do some experiments using the above guidance and see. Most likely, it will be more difficult, or the background blur effect won’t be as strong. You won’t be able to get photos with the soft backgrounds like I have with my 135mm on an iphone. It’s just not going to happen. Of course you can use portrait mode, but it does have some issues especially with the furry ears of long-haired dogs, because it’s an artificial blur and relies on the phone’s technology to recognise what is the subject, and what is the background. 

It’s also possible to blur the background in editing, but in my opinion and experience, this is VERY difficult to do in a way that appears believable and realistic, because of the way depth of field operates – it’s hard to mimic without some effort. There are probably apps out there which may be able to do it, again they will rely on being able to distinguish the subject from the background and blur only the background.

In my opinion, if you have a phone, your best bet is probably going to be using portrait mode. There is SOME depth of field if you get close enough to the dog, and some phones’ portrait modes and DOF will be better than others. 

If you have a camera, I would seriously recommend investing in a lens with a wide aperture (f/2.8 or smaller f/ number), and a mid to long length. Make sure you check out the “Choosing a Lens” lesson for more information. A good quality lens, with a wide aperture, can do wonders for your photography, as it can achieve effects that other cheaper lenses just can’t due to their construction. 


Distance from the subject to the background

The further the subject is from the background, the blurrier/softer it will be (relative to all the other factors discussed in this lesson). So, if you place your subject amongst the bushes, then a good amount of those bushes will be in focus. If you place the subject far away from the bushes, they will be blurry. Let’s have a look:

Distance from you to the subject

One big factor which affects depth of field (and therefore how blurry the background is) is how close you are to your subject. The closer you get, the narrower the depth of field will be. This is especially important with wider focal-length lenses, as you may need to have them in a very tight headshot in order for the background to be blurred.

This is a big reason that action photos can be especially difficult, as the dog closes the distance to us, the depth of field becomes narrower so the focus needs to be more precise, and the dog is quite a small creature so they are already especially close to the camera compared to other moving objects that we tend to capture with the camera like people, cars, horses, even birds in flight tend to be much, much further away. 



The closer you are to your subject, the narrower the depth of field, and… 

the further the subject is from the background, the blurrier it will be!

Try it yourself. Hold one finger up and close one eye, like you’re looking through a viewfinder. Start with your finger outstretched, far from your face.

Now move it very close to your face. The background should be much, much blurrier now than when you had the finger outstretched!

In each of the images below I have outlined the focal plane (the area which is in focus) between the two purple lines. Although the width between the lines looks the same, keep in mind the actual distance represented! In the first image, approximately 50-60cm of the image is in focus, taking in part of the grass in front of and behind Loki. In the second image, the area from just behind his snout to his ears is in focus, probably about 10cm. In the last image, only his single eye and a narrow strip of his face is in focus, probably about 2cm. 

These were all taken with the exact same lens at the same settings (f/1.8), with my 135mm lens. The only difference is how close I was to Loki. The closer I got, the narrower the depth of field became!

Consider these three images below, compared to the ones above.  These were taken with a 28-75mm, f/2.8  lens. You can see that it takes until the very close headshot to get a very blurry background. The middle photo is slightly soft, but definitely not blurry. 

Mountain examples

Below, you will see photos taken in more or less the same location. The settings for each are the same: f/3.2 with a 35mm lens. The only real thing that changes is the distance from me, to my subject. Note the difference in the background in each photo.

Again, same location, same settings. The difference? Distance from me to the dog. Note the difference in the blur of the mountains behind.

Multiple lens examples

Here, I took a series of photos for this lesson, to show you how varying my distance from the dog would affect the DOF and background of the image. You will see these again in the “Lens length” topic.

They have all only been very lightly edited. 

Each time I moved back slightly, but how far I was from the dog was relative to the lens. Eg., the closest photo with the 135mm was likely the furthest distance I got with the 35mm. 





Go out and take a series of photos as shown in the last examples in this lesson.

Take some photos as close as possible without chopping off the dog’s ears.

Now move back a little, take a photo. Back a little more, take a photo, etc, until you have 70% scenery, 30% dog in the scene.

Note what happens to the background each time you move back.