Exercise: Focus at different apertures

In this exercise I saw the impact of varying the aperture whilst leaving the camera in the same position, framing the same shot and using the same point of focus. I actually took 19 photos stepping through apertures from f1.8 through to f22.0 taking avantage of the range available on a 50mm prime lens. The three shots below are at the extremes plus one in the middle (f9). The camera was set to ‘aperture priority’ meaning whilst I took manual control of aperture, the camera was adjusting the shutter speed to ensure the best exposure for each shot.

Whilst aperture is not the only way depth of field can be altered, this is a good learning exercise of what it can offer in terms of control.

This is the photo with an aperture of f1.8, the point of focus is the first post, the depth of focus looks to be about 2-3 squares of fence to the left of the post and no more than 3-4 squares to the right. The next fence post is very much outside that depth.


This is the photo at aperture f9, the same point of focus (the first post) but this time all the fence to the left of the post seems to be in focus and the right, the second post is now also in focus, the depth of field (to my eye) extend around 3/4 of the way along the fence to the third post before trailing off.


The final photo, with an aperture of f22, this time the posts seem to be in focus as far as the eye can see.

Exercise: Focus with a set aperture

Three photographs this time to illustrate moving the point of focus at a set aperture, an aperture of F2.8 and at a focal length of 100mm. The eye is drawn in each case to the element (the duck!!!) that is sharpest in focus.

My preference is the middle image, I like being drawn into the photo by the piece sharply in focus being at neither extreme of the row of ducks. I like the soft focus on the first duck and don’t find it off putting. In the first and third image I find my eye trying to discard the ducks not in focus.

Last duck in focus.

Second duck in focus, my favourite.

First duck in focus.

Exercise: Focal length and angle of view


So the first exercise, three pictures taken at extremes of focal length. The first picture is taken with both eyes open looking to match what I could see in the viewfinder with what my other eye saw. After printing this up to A4 size by holding the photo up in my eyeline I had to hold it approximately 60cm away to make the actual plant and photo appear the same size. In th second photo focal length was increased considerably to 130mm. Again holding the printed version (A4) at full arms length the photo was still larger than the actual plant. The third phto was taken at the other extreme, a focal length of 10mm. The A4 print was brought as close to the eye as possible to focus and make the print the same size as reality. 10mm focal length

Why the blog?

This blog will be the learning log for my studies with the Open College of Arts, a journey I hope will eventually lead to a degree in photography. Until earlier this year I had studied little since A levels (more years ago than I care to remember). Earlier this year I took the excellent Open University T189 Digital Photography 12 week course. This proved to me that I was ready for learning (if I picked the right subject) and that I could manage the distance learning approach. The first course, The Art of Photography begins here….