SO WHAT IS DEPTH OF FIELD?

“Aargh! Stop! No more please…”

this was my typical response whenever someone tried, for the umpteenth time, to explain depth of field to me.  I don’t think I’m particularly stupid but I just could not for the life of me get my head around what aperture to use for shallow depth of field, what deep depth of field looked like or what the heck focal length had to do with anything anyway.

Understanding fstops and depth of field was one of the things I had the most trouble with as a fledgling photographer.  If this is ringing a bell for you and sounds familiar, don’t feel bad, it will all click into place eventually but let’s see if I can help get you a little closer to that mental click and aha! moment.

For any experienced photographers who’ve happened to land on this page, this blog post is probably not for you, it’s a beginner photography post, not an in depth digital photography tutorial on all the in and outs of depth of field.  Merely what my friend Pete Frielinghaus would call, “‘n tong tippie”, a tiny taste on the tip of your tongue, just enough to whet your appetite.

What is depth of field?

Depth of field describes how much of any given image is in focus from front to back.  For example, in the first image below, it’s really only the goose’s eye, part of it’s beak and head that’s in sharp focus, the rest of the image is out of focus.  We would say then that this image has shallow depth of field.

With the landscape photograph below however, quite a lot of the image is in focus and therefore we would say that that image has deep depth of field.

How can using depth of field enhance my photography?

Manipulating depth of field in a photograph is a handy tool to have for practical and creative purposes.

The poor goose in the above image was sharing a very dark and dirty pigsty with two pigs, naturally I didn’t want any of the pigsty to show up in my photograph.  By using a shallow depth of field I was able to isolate my subject and keep the messy background blurred and out of focus.  This in turn encourages you, the viewer, to ignore the background and pay attention only to the subject of the image which in this case is the beautiful blue-eyed goose and that is exactly what I wanted to achieve.

This landscape photograph is a sweet little scene, with cows calmly grazing on the rolling hills at the foot of the mountain blanketed in cloud and so I wanted the viewer to be able to see everything in the image and by using deep depth of field the viewer’s eye is encouraged by my use of elements like colour, shapes and leading lines to travel all around the image.  Most of the image is acceptably sharp and every element is recognisable for what it is, trees, mountain, clouds and cows.

Controlling depth of field in photography

Now that you know what depth of field is how the heck do you control or manipulate it?  Listen up photography peeps!  Aperture is not the only thing that affects depth of field and here’s the secret sauce recipe coming right up:

Depth of field and the illusion thereof is determined by 3 things : Aperture, shooting distance and lens focal length.

Aperture

This is the opening or hole in your camera’s lens.  Every camera lens has an adjustable opening that controls the amount of light coming through the lens, similar to the way the pupil in your eye works.  When we need more light to come through the lens we make the opening bigger, when less light is needed we make it smaller.

Besides controlling how much light comes into the lens, the size of the aperture has a huge affect on depth of field and this my darlings is where a lot of the magic happens:

Big aperture/opening = less depth of field.

Small aperture/opening =more depth of field.

Shooting distance

(a) Closeness to the subject – the closer you are to your subject the less depth of field you will achieve.

(b) Subject’s distance from the background – to blur the background we need to separate the subject from the background by at least 10 feet if not further.

Lens focal length

Using lenses of different focal lengths can change the way the background appears in relation to the subject.

Longer lens (telephoto)e.g. 85mm = Gives the illusion of less depth of field and appears to compress or bring the background closer.

Shorter lens (wide angle) e.g. 24mm = Gives the illusion of more depth of field and appears to magnify the foreground and push the background further away.

There are of course also “normal” lenses that give an angle of view similar to the way we see things naturally with the human eye and they too produce very pleasing images.  There are of course endless nit-picking arguments about which lenses are considered “normal” but the consensus seems to be anything between a 35mm to 50mm focal length.  Don’t bother about all the arguments and in-fighting, decide for yourself what looks normal to you.

EXPERIMENT TIME

Because you are all my peeps and I love you so, I did a little comparison experiment between the Canon 85mm lens and the 24mm lens, just to give you an idea of what we’ve been talking about.  For easy comparison, the exif metadata is posted below each set of images.

• Please note that the field of view (how much of the scene is visible) is much narrower with the 85mm lens (you see less of the kitchen) but with the 24mm lens the field of view is much wider (you’ll see more of the kitchen); don’t let that distract you from noticing what happens when we experiment with the various distances and apertures.

• In every single image the distance between the Yashica camera and the utensil bottle in the background was 1 metre but do you notice in the images taken with the 85mm lens the background bottle appears to be compressed and pulled closer but with the 24mm it appears to be pushed further away?

• Another thing to notice in each collage, is that the closer the photographer is to the Yashica camera, the shallower the depth of field appears to be.

• Lastly, pay attention to the fact that the bigger the opening in the lens (f/2.0 or f/2.8) the shallower the depth of field and the vice versa when we use a small opening like f/22.

OOPS! SORRY…

With the first 2 collages I intended to use the same aperture when comparing the lenses but only realised my error after the fact when I’d packed the tripod away and put my kitchen back into order, isn’t that always the flippin’ case?   I should’ve used an fstop of  f/2.8 on both but seriously folks, the aperture difference is minimal and doesn’t affect the experiment negatively, so don’t worry about it.

 

For the following 2 collages I used a smaller aperture of f/22 and it’s obvious that the depth of field (how much of the image is in focus) is deeper than in the previous 2 sets of photos.

 

 

That’s it peeps, I know it can be a bit much to take in all at once but if you read over the post a couple of times you should be able to hear the penny drop eventually.  Better still, take out your camera and do some test shots yourself, it’s the best way to learn.

If your appetite for photography has been well and truly whetted and you’re excited to learn more, now is the perfect time to take my online course.  It covers all the digital photography basics including learning how to photograph in manual mode and lots more.  I keep the classes small so that I’m able to give individual attention to each student’s work, the course is mentored personally by me from beginning to end and nobody is fobbed off onto a “teaching assistant”.  Personalised video feedback is given for all the image assignments and I’m available to assist and answer any photography related questions for the entire 5 weeks.

The next course begins on Monday, 7 March, 2016 – seats are limited, oh! and gift vouchers are available.

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Have a beautilicious day