DOF - Sharp portraits and blurry backgrounds
You have probably seen striking portraits on Instagram or pinterest where the model is razor sharp and the background seems to melt into a pleasant combination of soft shapes and lights, enhancing even more the primary subject, creating a sense of depth to the image.
By the way the fancy name for this creamy background effect is Bokeh, I’ll make a post with photography terminology soon enough so don’t bother with it for the time being.
Then you look at the pictures taken with your phone during a holiday trip and it looks flatter than an ironing board. Everything is in focus and they just don’t look “professional”.
You can blame this on a little thing called depth of field. In simple terms it means how much of the image is in focus. to give you an idea do the following experiment. point towards the ceiling with your finger and bring it close to your face, in between your eyes like you’re trying to measure your nose.
You will notice how your finger looks sharp and everything else begins to blur. Cameras work in a similar way, their sensor being an eye which chooses where to focus.
Most mobile phone cameras are unable to create this effect because they have been built to try and keep everything in focus to make it easy for non photographers to capture in focus images (although some phones like the iPhone 7 plus fix this with a dual camera setup).
How is this useful?
Depth of field is one of the pillars of photography, it is used in everything from landscape to portraiture and wildlife photography, each with its own focus and techniques.
The key here is that each one needs something different from Depth of field.
Landscape artists might want to have a crisp image all across the frame, wildlife photographers would vary depending on the situation, and portrait photographers most of the time want what I like to call “The Crème brûlée effect”; sharp foreground subject and a creamy soft background so as to not compete for attention.
The depth of field is governed by 2 main factors: aperture and focal length or distance
Let’s begin with aperture.
Aperture is how much the lens opens and closes on every shot, the smaller the number the larger the aperture (so f1.8 is wide open f32 is very small).
a wide aperture will give you a very shallow depth of field, meaning that very little of your photograph will be in focus, ideal for portrait because you can keep just your subject in focus and everything else is blurred out.
A small aperture (f11-f32) for instance will have the opposite effect, more things will be in focus so landscape photographers would find this useful.
Here is a comparison of 2 pictures, one with a wide aperture and the other with a narrow aperture.
Wide Aperture (F 1.8)
Small Aperture (f16)
Here is very clear how depth of field affects an image. on the one on the left, the depth of field is very shallow, this creates an isolation of the subject, in this case the kiteboard, while the background doesn’t compete for the attention but rather frames the subject.
The one on the right is the opposite, I wanted to have everything in focus to provide a visual cue from which to drift into the distance.
This is the power of aperture in depth of field.
Focal distance is another important factor when talking about depth of field. In general you can think of it this way, the longer the focal distance the more the subject is isolated from the background. Again I will do a post with the different effects of focal lengths on subjects but for now that’s all you need to know for now.
If you are doing portraits, you want a longer focal length (above 50mm lens ideally) and if you’re doing landscape usually a wider length is best (smaller than a 35mm lens)
there are many nuances regarding focal length which I will cover in detail later on so if you’re interested check back soon, or join the newsletter for news on when it’s up.
Here's a picture of a Zebra because I think they're cool and it shows a good DoF as well
That’s everything! honestly depth of field is super useful because it takes your pictures, particularly portraits from police mugshots to actual works of art. Mastering this very simple concept will yield a tremendous improvement in your photographs so remember
Portraits – Shallow DoF -> Long Lens with wide open aperture
Landscape -> everything in focus -> Wide lens with narrow aperture
I would love to see your pictures so if like post them here and share them with the whole community!