DigitalCamFan
Depth of Field
Circles of Confusion
This past week we did an aperture assignment to see what would happen if we set up our camera on a tripod and took a few picture on aperture priority. The only setting we changed was our aperture by 1 stop each time. Result - The wider the aperture the more shallow depth of field you end up with.
After reading up this week as to why this happens I came across many posts that talked about the circle of confusion. This circle confused me even more. What I did learn… there are three factors that influence depth of field:
- The focal length of your lens
- The distance between you and the subject
- The aperture you select
This week we’re working with aperture settings. The best example I came across was actually in a book – Understanding Exposure by Bryan Peterson – Quoted from the book:
“Imagine using a funnel with a very small opening and pouring a one-gallon can of paint through it in to an empty bucket. Compare this process to pouring a one-gallon can of paint in to the same empty bucket without the aid of the funnel. Without the funnel, the paint gets into the bucket quicker, but it also splatters up on the bucket sides, as well. With a funnel, the transfer of paint to the bucket is cleaner and more contained.”
What a great visual! When you use a smaller aperture like f/22 your pictures will come out neat and sharp, but if you want to add a dash of blur to your image open wide and go for that splash with a f/2.8 or f/5.6.
Of course that is only one piece to the puzzle when it comes to depth of field we still have focal length and distance between you and the subject, but it’s a start!
For a great technical resource check out Cambridgeincolour I thought they did a great job explaining Depth of Field!
Understanding DOF (Depth of Field)
I currently have one example on shallow DOF. I am currently working on getting some more tests done with different focal length. This example is only about 1 foot away from my subject – Shallow DOF
What affects depth of field?
- Aperture (F-Stop)
- Focal Length
- Distance from the subject
Aperture (F-Stop)
Smaller aperture (higher number) will give us more depth of field
Larger aperture (lower number) will give us less depth of field
You will hear the term larger aperture or smaller aperture a lot. A larger aperture is going to let more light in (like an f/1.4) and smaller aperture is going to be a smaller hole and will let less light in (like an f/32)
- F/1 – less depth of field
- F/32 – more depth of field
Focal Length
Distance between the sensor and the optical center of the lens.
16mm shorter distance means greater depth of field
Zoom – longer distance means lesser depth of field
Distance from the subject
As distance between the sensor and the subject changes so does the depth of field. If we are close to our subject we will get less depth of field. If we are further away we will get more depth of field. When you are very close to your subject the amount of depth of field will be almost nothing.
Further from subject – more depth of field (more of frame in focus)
Times you want more DOF (Depth of field)
- Architecture
- Landscape
- Macro (sometimes)
Closer to subject – less depth of field (smaller amount in focus)
Times you want less DOF (Depth of field)
- Portrait
- Wildlife
- Macro (sometimes)
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