Ok. How much we can blur the background will depend on a number of factors. Your aperture affects the Depth of Field (DoF). DoF is the amount of the scene that is in focus. So, we want to get the smallest DoF that we can. What we call a shallow depth of field.
Let’s see how we can do this
1. The Aperture
We know that a larger aperture/opening (smaller F number) will blur the background out more. So, to get this blur, it’s best to shoot at the largest aperture our lens can go to. For a kit lens – the lens that came with your camera when you bought it, the largest aperture you can get is usually F3.5. To help blur the background, set the aperture to this. If your lens can get to a larger aperture – F2.8, use that.
2. The distance the subject is from the background
Moving your subject as far away from the background as possible will help to further blur that background.
3. The distance you are from the subject
If you stand back and zoom in, this will appear to blur the background even more. With some kit lenses, zooming in like this will automatically change the aperture to F5.6 – a smaller opening. We may think this will give us a larger depth of field – more of the scene in focus – less blur in the background. But, in reality, it doesn’t.
Let’s put all of these together and see what happens.
Here are a few photos that will help you to understand how to get that blurred background. I have tried to keep the bottle much the same size in all photos so that we can see the difference that aperture and distance have made. I used a single focus point in all photos and it was focused on the bottle.
Photo 1:
This is shot at F8. I was zoomed out wide at 24mm. At this focal length (24mm) we can still see quite a lot of the room.
The bottle is about 18 inches from the book in the background. You can read the authors name on the book and the name of the book. You can make out some details of what is on the shelves in the background and the picture on the wall. F8 gives quite a large depth of field.
Photo 2:
This photo is shot at F4. This will give a shallower depth of field, helping to blur the background a little more. I am still at 24mm. We can still see quite a lot of the room. The aperture is larger and this gives a shallower depth of field – the slice of the scene that is in full focus is smaller.
So in this shot, the background is more blurred. It is more difficult to read the name of the book. The books and stuff on the shelves are less detailed. The newspaper on the right is less detailed.
In this photo, F4 gives a shallower depth of field and makes the bottle stand out more.
Photo 3:
In this shot, I have moved the bottle further from the background. My aperture is F8. I have also stepped back and zoomed in to 70mm. The bottle is still pretty much the same size as it is in the other photos.
Because we are zoomed in, there is less of the room visible and the bottle takes more prominence in the shot. The background is partly blurred out.
By moving the bottle away from the background and zooming in, we have created more background blur in comparison to the first photo that was also shot at F8 but at 24mm.
Photo 4:
The only difference between this photo and the previous photo is the aperture. I changed it to F4. The bottle is still in the same position on the edge of the table. I am still zoomed in to 70mm. But you can see that the background is blurred out even more in this shot. An aperture of F4 has created a more shallow depth of field.
So, what we have learned here is, in order to blur the background, we need to select;
- The largest aperture (smallest F Number)
- Move the subject further away from the background, and
- Step back from the subject and zoom in.
You can blur the background even further if you have a lens that goes to a larger aperture. The 50mm, F1.8 lens is probably one of the nicest lenses you can buy and at F1.8 will blur the background a lot.
Photo 4:
This last photo was shot while zoomed in and at F1.4. See how much more blurred the background is? Using aperture and distance is something that you will have to practice at but once you understand how it works, your photography will never be the same again. Using the above techniques, great blurry backgrounds are also entirely possible with the standard F3.5 kit lens.
Getting your head around aperture and how it relates to depth of field is one of the trickiest things you will learn about when taking photographs. It will take a little time and a practice to understand, but the day will come when all the pieces of this jigsaw will pop into place.
In the real world, you will use these techniques to shoot photos like these. This brings the subject to the fore and allows the viewer to connect and engage with them.
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