Understanding Depth of Field and Focus

 

Focus is EVERYTHING when you want to take a beautiful photo.

 

I am going to try to teach you how to focus using

FOCUS POINTS on your DSLR camera plus

explain DEPTH-OF-FIELD and how it is controlled with aperture.

 

I know it sounds scary, so I'm not going to include lots of

confusing math....just the very basics that you will need to

 FINALLY get the correct focus all the time!

 

This tutorial is only for DSLR cameras because they allow

you to take control of your focus.

 

Let's start with that comfortable AUTOMATIC mode you are probably

using, and wondering why your subject's face isn't in focus all the time.

 

I shot this in AUTOMATIC:

 

 

In Automatic, you allow your camera to select where to focus.

 

This did a pretty good job.  You would probably post this on Facebook,

 but lets go in closer and see that...

her eyes are not sharp:

 

 

Now, let's zoom in on the bowl of gourds she is holding...

TACK SHARP.

This is where the automatic mode chose to focus.

 

 

Time to go into the manual modes and take control of focus.

 

To make it easy...we'll go semi-automatic and use the AV mode or Aperture Priority

mode on a Canon.  "A" mode on a Nikon.

 

 

 

Read your camera manual to learn how to set this on your specific camera.

 

In this mode, you get to choose your aperture and the camera will automatically set the

shutter speed to give you a good exposure.

 

If you find that your camera is setting your shutter speed below 1/125, (In a darker situation.)

you will need to raise your ISO until you get at least a 1/ 125 shutter speed to avoid

hand shake blur.

 

Next, read your manual and learn how to use FOCUS POINTS.

This takes practice to learn how to use them, but it will

change your photography forever.  You will no longer have

blurry eyes! 

 

DSLR cameras have a grid of focus points that you can move around

and place one directly over an eye or whatever you want in tack sharp focus.

 

In this next photo, I want to focus on the fried eggs, so I set my red dot

focus point directly on the eggs.

 

 

 

By using focus points, you will finally be able to create those

artistic photos where the exact item like these fried eggs is in perfect focus

while the surroundings are blurred.

 

 

Once you learn how to use focus points, you are

ready to understand depth-of-field and how to

control it with aperture.

 

Depth-of-field is the distance between the nearest and farthest

object in a photo that appears acceptably sharp.

 

When photographing a person, you should set your focus point

on the eye closest to the camera...unless you're creating some kind of artistic

statement and want to focus on the tip of the nose.

 

So let's say your focus point is on the closest eye.

That focus point on the eye becomes the center of your

depth-of-field and will be in tack sharp focus.

 

By showing the side view, we can see this

depth in front and in back of the focus point.

 

With this depth-of-field, we can see that her entire face and hat will

be in focus, but the front of the bowl of gourds and her mittens will blur.

 

 

Aperture determines how much in front and in back of your

focus point will be in focus.

 

Aperture is how much your lens opens up to let in light.

 

 

The BIG hole is a big aperture, but to make it very confusing...the

lower the aperture number the bigger the hole/aperture!

 

So, an f 1.4 is a BIG hole/aperture

and an f  22 is a SMALL hole/aperture

 

I know...totally confusing...but once you wrap your brain around it,

it becomes second nature.

 

REMEMBER THIS:  The bigger the aperture the smaller the depth-of-field!

 

So, it makes sense that if we want the eyes in focus, but lots of pretty

artistic blur, we will want a bigger aperture.

 

Let's start with a BIG aperture with the small number... f 1.4.

This is the biggest aperture on my 50mm lens.

 

Since the bigger the aperture, the narrower the depth-of-field,

you can see in this next photo that when you set your focus point

on the eye....not much else is in focus.   Even the tip of the nose is not in

focus!  Most of the hat is not in focus, her ears are out of focus.

 

 

If my subject is facing me square on with both eyes on the same plane,

the f 1.4 will create a lovely photo with both eyes in focus.

It's okay to have facial features out of focus as long as your eyes ARE in focus.

 

But, if her face is angled even a tad...

the eye furthest from the camera leaves the narrow depth-of-field

and is no longer in focus!

 

Notice the gorgeous bokeh (artistic blur) in the background!

This is why portrait photographers want to use the biggest

aperture possible and still get those eyes in focus.

But the f 1.4 is too narrow to get the angled back eye in focus.

 

 

You need to be very aware of aperture and depth-of-field while shooting

in bigger apertures.

 

Let's keep her angled face and close down the aperture a bit to f 2.8

creating a tad larger depth-of-field to include the eye that's a bit farther back.

 

 

 

Let's go in closer to see that both her eyes are in focus,

but the aperture is still big enough to create the gorgeous bokeh in the background. 

 

 

Let's close down the aperture to f 5.6 and see that more is in focus,

plus the bokeh is  smaller. (But still pretty.)  

 

YOU get to choose

the look you want in your photo and YOU get to create it by choosing

the aperture and thus your depth-of-field!

 

 

A quick summary:

 

Select your aperture based on what you want in focus

 

Smaller number aperture means wider open hole in lens.

 

Larger hole in lens means narrower depth-of-field and less in focus.

 

Focus on the eye closest to the camera!

 

 

You may have to read this over and over...but once it clicks in your mind...

you'll be clicking your camera like crazy

and nailing focus EVERY TIME!