Exercise 2: Exercise: Focus with a set aperture – cameras with a manual option
2 – 3 photographs
Find a scene which has depth — a wood full of trees, for example, a row of cars seen from an acute angle, or a crowded
market. From the same place take two or three pictures, each focused on something at a different distance. (For this to work, the
lens aperture must be wide – at its lowest f-stop number.) When the photographs are processed, compare them. Notice first how the sharp
focus draws the attention, and also how a sharp subject stands out very clearly against the out-of-focus surroundings. Which version do you prefer? Enter in your learning log, as clearly as possible, why you prefer one photograph over another.
For this exercise we were asked to find a subject where a number of elements moved away diagonally from the viewfinder. I decided to take these shots of a row of toy soldiers.
For the fist image I focused on the front soldier.
The next image focused on the second soldier but the depth of field from a fully open aperture bought some of the front and third soldier into focus
The third image moved the focal plane back to the third soldier loosing focus on the first but gaining some focus on parts of the fourth soldier
The fourth predictably took the focus back one soldier and as we can see the depth of field was about one soldier plus or minus about half a soldier meaning if I focused on the space between two they may both be in focus.
Due to the uniform size of the soldiers the results have become quite predictable we can see from the sequence so far that we have about two soldiers in-depth of field at f5.6 the widest aperture at this focal length. As the bases of these soldiers are 20mm square It suggests that at this aperture and focal length the depth of field is about 40 mm.
We have reached the back soldier the focus is actually on the one before last but the depth of field has started to bring parts of the last soldier into focus
The Final image leaves the last soldier in focus with the depth of field bringing parts of the second to last soldier into focus
If I had to select an image I think it would be the second one because it has a nice group of soldiers in focus in the foreground and compositionally I want to see the first soldier in sharp focus. This unfortunately has not really happened here and I would probably re shot this to capture a sharp focal plane that concentrated on the first soldier but allowed some of the second soldier to come into focus.
I do not really like the images that have the focal plane in the centre or the rear as the subject demands that with soldiers seemingly marching toward you it should be the front rank in focus and the rear ones gradually dissolving focus.
If I had taken a different subject like a fence etc the story may have been different depending on the motivation of the subject. I do not think there is a right or wrong answer to this and the answer would depend on the purpose of the image and the artistic taste of the viewer.
When I set this up I stuck all of the soldiers to a line of masking tape so that they would stay in place and not move and spoil the composition, I decided to set them up at about 45 degrees to the camera so that there was a clear movement away from the camera that would allow this exercise to demonstrate its point.
I set the soldiers up in a light tent with a black background and two fixed lights with daylight bulbs, the typical sort used for product type shots, because of the white nylon of the tent the bulbs cast a very even soft light on the subject. I have found that the closer you place a light the bigger a source it is and the softer it is on the image, this was a revalation I picked up taking a short course in photographic studio lighting, I also learned that putting a difuser in front of the light made the whole difuser the source and hence made it a softer light, the effect of the tent is to give a very soft difuse light which works well in showing the effect of this exercise. The toy soldiers are made from grey plastic and have not been painted, the effect this gives on the black backround is that the images look like they were shot in black and white even though there is clearly other coloured light at work in these images.
Over all I am pleased with the results of this execise which clearly show that the lens has a small depth of field at the widest aperture and demonstrates that there are important decisions to be made about the positioning of the focal plane when composing an image. I have discovered in the time since taking these images how important this lesson is in the development of a workflow and in getting a composition that works. Misplacing the focal plane can give the impression that the image is out of focus or not sharp. It leads the eye to a specific place in the image which if set incorrectly can unbalance or even alter the intent of the original image.
This idea of getting the origin of the focus is a really important part of my developing workflow for taking images, one that constantly catches me out when balancing it against everything else that needs consideration in the construction of an image. for more of my thoughts on focus and the problems I had see my post called Focus aVoyage of Discovery