Btec Art&Design: Aperture

Aperture.

What is aperture?

Aperture refers to the lens diaphragm opening inside the lens, this regulates the amount of light passing through onto the recording medium at the time of exposure.

What is aperture Priority?

Aperture priority is a system inside a camera where the aperture is set by the user and the appropriate shutter speed is controlled automatically

F numbers

the list of f numbers goes from f/1.8 f/2.0 f/2.8 f/4.0 f/5.6 f/8.0 f/11 f/16 f/22 f/22 f/32 f/64.
This picture shows the different aperture opening size according to f numbers.

What is depth of field?

Depth of field (DOF) represents the distance between the furthest and nearest objects in a scene that appear clear or sharp in the image. Its basically shows how one object nearer to the lens can be in focus and that fades out to create a fuzzy background or visa versa
A large aperture equals a small depth of field f/2 etc. It shows a smaller range of focus.
A smaller aperture equals a larger depth of field f/16 etc. There will be a bigger range of focus. More objects in the image will be clearer.

The aperture on this photo I would say would be f/2.8, as the ball in the background is very hazy and blurred, suggesting the focal point to be much closer to the lens. So I'd say the focal point was centred to the number on the ball.

2. As for this photo the depth is much larger, as you can see a further variety of detail which would suggest the aperture is be much larger so maybe for the particular shot I'd estimate the f/number to be at f/22. The focal point for this image is much more centred as the f/number is larger so I'd say the focal point is probably in the middle of the road where the aperture blurs out.

3. For this image the aperture seems to be a lot smaller then the last as the photo itself is much closer compared to the landscape one, but it also seems much more blurred compared to the first image so I'd say the aperture is around f/2 and the focal point is on the second light bulb. As that has the most sharp and defining edges.

My own photos of aperture and depth of field.

For this experiment I played around with dof and aperture taking a series of shots to see how they both effected each other. For this experiment I used a Nikon D3000.

This photo has a aperture of f/3.5 where the flower is the focal point of the image. Where the aperture is larger the focused area is smaller so the surrounding background is blurred out. Only the objects on the same plane as the focus point remain in focus.

This photo has a aperture of f/22 as more detail is in focus. This shows that the depth of field (dof) is much larger, for this I also played around with the focus point, I zoomed out on this particular photo so the range of focus is more centred instead of just on the yellow flowers.

For this photo I changed aperture to f/8 and the dof. Basically by using this aperture I changed the focal point of the image from the yellow flowers to the grass and leafs in the background. Its kind of a reverse of my first photo.

For this image the aperture was set at f/22 and much like my other set of photos I was playing around with the dof but for these I wanted to have more going on within my photo so the dof would be more obvious. Where this was shot at f/22 the focal point is much more central meaning the central area of the flowers was more in focus then the otter edges. More detail can be seen using this aperture.

This photo has an aperture of f/3.5 with the focus lens zoomed out to give a clearer shot of the purple flowers. Where the focal point is on the purple flowers that are slightly off centre everything in line with them also comes into semi focus and the background just fades away. The dof is much smaller compared to the previous photo.

This photo was the last in the sequence of photos I shot while playing around with aperture and dof. I used a f/8 for this but changed the focal lens by zooming it back in so the area of focus becomes more unclear and un-centred because there is so much going on within this photo. The focal point is definitely still on the front row of flowers but more depth and detail can now be seen behind that because the aperture has gotten smaller whereas the dof has gotten larger.

This set of my own photos shows aperture using a Nikon D3000