Monday 2 April 2012

Focus at different apertures

Exercise: Focus at different apertures (3 Photographs)

This exercise is similar to the previous one, the difference being, instead of remaining with a fixed aperture, the aperture is varied on each image to demonstrate the how a change in aperture will change the area of focus. In the previous exercise only a small area of the image was in focus at any one time. In this exercise I will demonstrate by changing the aperture, you can vary the area of focus of a small area of the image to the entire image being in focus.

The camera was mounted on a tripod so that the frame remained the same for all of the images.


Image 1 

Image 1, was taken at a shutter speed of 1/640sec at an aperture of f2.8, if you remember this was the same aperture that was used on all the images of the previous exercise. The red dot on the centre of this image signifies the point of focus.

The arrows in the background and foreground point to the areas where focus has been lost, signifying that this image has a shallow depth of field. This is not a surprise as the previous exercise demonstrated. 


Image 2 

Image 2, was taken at a shutter speed of 1/60sec at f9. The point of focus remains the same, however the area of focus has increased. The rock indicated by the arrow in the foreground is now almost in focus, and the arrow in the background indicates where the area of focus ends. As you can see by reducing the aperture from f2.8 to f9 has had a marked affect on the area of focus. 


Image 3 

Image 3, was taken at a shutter speed of 1/10sec at f22. As you can see by the arrows the area of focus is now from the very front of the image to the back, if it wasn't for the Devon haze!, it would be in focus to the horizon. 

In conclusion this exercise demonstrates, that the aperture used has a marked effect on the amount of the image that remains in focus. Thereby having a huge creative effect on the final image. A landscape photographer may well use an aperture of say f16/f22 to give back to back focus in the image, whereby and portrait photographer may well use an aperture of f2.8/f4 to isolate the model from the background. 

    


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