Understanding depth of field and how aperture and shutter speed settings affect your product photos

Written by Jo Bradford of Green Island Art Studios. A fortnightly series to improve your product photography and help you make a success of selling online. Great product shots will give buyers increased confidence in your handmade items and supplies.

Today’s topics sound pretty technical, but don’t be put off! It is easy to get your head around it all, and it will make a big difference to your photos if you understand these basics.

Don’t forget, if you need to find out something specific about your camera and its modes, check your manual (if you can’t find your manual download a copy from your camera manufacturer’s website).

Camera Aperture and shooting in Aperture Priority (AV) mode

I told you last time that “Aperture priority mode allows you to make creative decisions about the range of focus in you picture. You will be able to focus just on your product and have everything else fade into beautiful blur. This is one of the most creative effects available to you”

Today I am going to teach you how to get that beautiful blur. Aperture Priority is a semi-manual mode on your camera. In this mode you are not ‘copping out’ and using automatic mode, instead you are shooting like a pro! In aperture priority mode, you, the photographer, set the desired aperture size; the camera does some maths for you, and sets the best shutter speed for the shooting conditions. So when would and how do you use Aperture Priority mode?

Aperture priority mode is usually set by the dial on your camera; it is commonly signified by the letters AV or A. To help you locate it, the AV mode is usually next to the Manual mode (M) on the dial.

by aquamizuko on flickr

In this illustration you can see that Aperture Priority mode is denoted by the letter A. (There it is in the picture above, tucked in between the S and the M)

People without an AV feature on the cameras don’t despair – I will explain shortly how you can achieve the same effect using your compact cameras too!

I am sure you already know that the shutter is the little ‘curtain’ that opens briefly when you press the button to take a photo (technically the button is called a ’shutter release’). The shutter lets the light (and thus the picture) into your camera. Shutter speeds can be long or short depending on the conditions, but more about that later.

Before I explain about using your camera’s Aperture Priority feature, let me explain what the aperture is.

Aperture

Think of the aperture as the eye of the camera, it’s the hole in the lens that lets light into the camera. Just as the iris aperture in our eye opens up in low light to let more light in and narrows in bright light to let less in – camera apertures work the same way.

The aperture size is usually expressed as something called an f-stop or

f-number. To keep you on your toes, there is a strange thing to learn about

f-stops……a large aperture is expressed as a low number e.g. f2.8. I know it is nonsensical but that’s the way it is.

A small aperture is therefore expressed as a big number e.g. f16. Check out the diagram below to help you understand.

The aperture size affects the amount of light let in, and it also affects the depth of field.

The what? OK, so now we need to take a little detour to find out what Depth of Field is.

Depth of Field

Depth of field (DoF) might sound rather technical but it is a very simple idea to grasp, so stick with me……..

The depth of field is the zone in which objects from near to far are in focus in your photograph. You can set a shallow DoF or you can set a wide DoF, or you can set anything that falls between those two extremes.

A wide depth of field is where everything in the picture is in focus, so objects in the foreground, the middle ground and the background are all equally sharp.

A shallow depth of field is when only a specific area is in focus and everything else in front and behind it is artfully out of focus.

by JoBradford on flickr

So how do you achieve these different depths of field? Well this is where the aperture comes in!! (See, we got there in the end!) Basically, by opening or closing the aperture, you control the DoF, thereby controlling how much of your image is in focus. It’s as simple as that.

For product photography, you will usually want to focus solely on your creation, so using a shallow depth of field will be perfect, it will throw everything else out of focus, this way nothing distracts from your product. Setting a large aperture of anything from f1.4 up to f5.6 will achieve this shallow depth of field perfectly. So go on – turn your dial to AV and set your aperture to a nice low number, and get snapping!

Shutter Speed

A point to bear in mind here is that sometimes the camera will set a shutter speed that is too slow. When shutter speeds are too slow, you cannot handhold the camera. It is simply impossible to hold the camera still for the length of time that the shutter is open, the rhythms of your heart beat and breathing will make the camera shake and you will get blurry photos. When you set your aperture in AV mode and your camera sets the shutter speed for you, make sure that the shutter speed is not slower than 1/60 to prevent this.

Ideally a shutter speed of 1/125 will be fast enough to avoid camera shake. If your desired aperture requires that your shutter speed is slower than 1/60 then you will need to put your camera on a tripod. If you don’t own a tripod I strongly suggest that you invest in one, it’s an essential tool for every product photographer. If you can’t stretch to buying one straight away then you can make do with resting you camera on a steady surface such as a table or a stack of sturdy books.

Cameras without aperture priority shooting mode

Now, for those of you that have a little compact camera that does not have the AV feature, don’t worry, you can still achieve the same results.

On your camera simply use the portrait (picture of a head) setting for a shallow depth of field that just has the subject in focus and blur in front and behind. Simply use the landscape (picture of a mountain) setting to get a wide depth of field with everything in focus.

Try it yourself

Ok, so here’s your assignment, the best way to get your head around the Aperture Priority mode is to get your camera out and have a play. Set up an object like a flower or a tin of beans (whatever comes to hand!!) on a table or a windowsill; somewhere that has good light. Set your camera to aperture priority mode and take lots of pictures. Start at the largest aperture you can (lowest f-number) and see how the background blurs. Work your way through the available apertures that your camera has. Go all the way to the smallest aperture (highest f-number) look at how everything is in focus in this photo. As you work, watch how the camera changes shutter speed to compensate for the changes you make in aperture size.

Now look at your pictures and see how the focus changes as you move through the range. Notice the point where handholding is no longer stable enough for the shutter speed. Try using a tripod for the slower shutter speeds and see what a difference it makes to your photos.

You should now understand the relationship between the aperture and the shutter, you will be able to see how having a large aperture hole means that the light gets in quickly so you only need the shutter to be open for a brief time, whereas when you set a small aperture of say f.16 the shutter has to be open for a lot longer to get all the light through the tiny hole.

Don’t expect to be a master after one session, but if you practice shooting in this mode and making your own creative decisions about the amount of focus and light you want in your pictures before long you will be turning out some great shots and you will know exactly how you achieved them, and then you’ll know it was worth the effort you took to learn this cool new skill!

Okay my budding folksy photographers, that’s all for this week, I will see you in a fortnight for the next instalment!

Happy shooting,

Jo

Useful Links

Depth of field – www.cambridgeincolour.com/tutorials/depth-of-field.htm

Jo Bradford is currently the Photographer in residence at Plymouth College of Art and Design – find out more about her work at www.jobradford.com or visit her Folksy shop at Green Island Art Studios