Exercise 3: Focus at different apertures - cameras with a manual option
(3 photographs - Prints needed to note results)
For this exercise, find a similar subject to the previous exercise. One that will show the results very clearly is a row of thinks seen from the angle: railings, parked cars, terraced houses, for example. Stand at the angle to this row and, if you have a tripod, set the camera on it so that each photograph will be framed identically. Focus on an obvious point somewhere near the middle, and make a not in your field notebook of this focus point.
Take the first picture with the lens at its widest aperture (lowest f-stop). Take the second with the lens stopped down to the mid-point of its scale of numbers. Take the third with the lens at it smallest aperture. You will, naturally, need to adjust the shutter speed so that the exposure stays the same, or have the camera set so that automatically adjust the shutter speed for a constant exposure (AV). Remember that there is a reciprocal relation ship between shutter speed and aperture. Just as shutter speeds are graduated in steps that double or halve the time (and so the exposure), the main steps in the aperture control are separated by the same amount. Each stop down from the widest aperture halves the area of the circular opening. This means that, in practice, one stop down to a slower speed accompanied by one stop down to a smaller aperture makes no change to the exposure.
In the aperture diaphragm a set of curved blades close and open in synchronisation to give different sizes of an approximately circular aperture. Each mean step halves or doubles this opening, so halving or doubling the exposure. These steps are f-stops and are calculated by dividing the lens´focal lenght by the effective aperture. The standard numbering sequence of f-stops proceeds in steps which half the illumination and is as follows:
f1, f1.4, f2, f2.8, f4, f5.6, f8, f11, f16, f22, f32 and so on.
For this exercise, find a similar subject to the previous exercise. One that will show the results very clearly is a row of thinks seen from the angle: railings, parked cars, terraced houses, for example. Stand at the angle to this row and, if you have a tripod, set the camera on it so that each photograph will be framed identically. Focus on an obvious point somewhere near the middle, and make a not in your field notebook of this focus point.
Take the first picture with the lens at its widest aperture (lowest f-stop). Take the second with the lens stopped down to the mid-point of its scale of numbers. Take the third with the lens at it smallest aperture. You will, naturally, need to adjust the shutter speed so that the exposure stays the same, or have the camera set so that automatically adjust the shutter speed for a constant exposure (AV). Remember that there is a reciprocal relation ship between shutter speed and aperture. Just as shutter speeds are graduated in steps that double or halve the time (and so the exposure), the main steps in the aperture control are separated by the same amount. Each stop down from the widest aperture halves the area of the circular opening. This means that, in practice, one stop down to a slower speed accompanied by one stop down to a smaller aperture makes no change to the exposure.
In the aperture diaphragm a set of curved blades close and open in synchronisation to give different sizes of an approximately circular aperture. Each mean step halves or doubles this opening, so halving or doubling the exposure. These steps are f-stops and are calculated by dividing the lens´focal lenght by the effective aperture. The standard numbering sequence of f-stops proceeds in steps which half the illumination and is as follows:
f1, f1.4, f2, f2.8, f4, f5.6, f8, f11, f16, f22, f32 and so on.
__Please click on the photographs to see camera settings.
My feedback
It was for me very difficult to find a good subject. First I wanted to do this exercise in the park with flowers, but as it is winter and I not live near a park I decide to try it out on any object in the city centre of Paris. I shoot 4 photographs to see better the difference between the widest aperture and the smallest aperture.
I diffidently going to practice more with this in the park, although I had some previous experience with this exercise.
My feedback
It was for me very difficult to find a good subject. First I wanted to do this exercise in the park with flowers, but as it is winter and I not live near a park I decide to try it out on any object in the city centre of Paris. I shoot 4 photographs to see better the difference between the widest aperture and the smallest aperture.
I diffidently going to practice more with this in the park, although I had some previous experience with this exercise.