Saturday, 12 February 2011

Project:Focus - Different Apertures

The aim of this exercise is to determine the effect of different apertures on the same scene.

I have tried several images for this exercise, but so far due to the flat overcast February light it has been hard to get the modelling required to clear define the areas of focus. These so far are the best set with a good clearly delinated areas of focus.

I tried to keep the same exposure, by using aperture priority, for each shot but once again was cursed by the changeable weather and light levels. Even using a tripod I wasn't quick enough as the clouds kept drifting across the sun... again and again...

I used the 50mm lens for this due to it's very wide range of f/stops from 1.4 to 22.

Image 1 clearly shows the small area of focus (marked within the yellow lines) with the fall off towards the lens clear in the lack of sharpness in the grass at the foot of the picture.

Project:Focus - Different Apertures
Image 1:
Focal Length: 50mm
Aperture: f/1.4

Image 2 shows how by moving to the middle of the available f/stop range that the area of focus has increased. Focus is improved towards the edges and corners but it is still clear that there are still areas where sharpness starts to degrade and makes it difficult to define separate blades of grass on the lower limit of the image.

Project:Focus - Different Apertures 2
Image 2:
Focal Length: 50mm
Aperture: f/5.6

Image 3. was taken using the limit of the range, in this case f/22. It can be clearly seen that even towards the edge of the image all details can be clearly seen and separate blades of grass are evident on the bottom edge of the image.

Project:Focus - Different Apertures 3
Image 3:
Focal Length: 50mm
Aperture: f/22

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