Exercise 2: Higher and Lower Sensitivity

In this next exercise of the Light section of the course I am looking at sensitivity in digital photography and how ISO, formally ASA settings effect noise within an image at different values. The ISO settings determines the sensitivity to light of the sensor. Taking image at two significantly different settings, the very lowest of 100 ISO and again at 800 ISO. I choose to photograph my local market, giving me a varied amount of movement, people and areas of light and dark.

100 ISO:

Each of these first images show to various degree the effects of using a low ISO however the need to then photograph at a slower speed to allow enough light to the sensor reduced significantly the sharpness of images, be that when viewing the whole image or a cropped section like we have here.

In the images directly above and below we have a more subtle difference in sharpness, the differences between the full view and the cropped are significant in terms of sharpness and clarity however overall the full size images are of a acceptable finished quality, perhaps not pin sharp but for the style of photography I would use them within they have an interest to them that makes up for the lack of sharpness in areas.

In these images taken at 100 ISO noise isn’t that obvious unless we look at the darker areas of the cropped images, however the overall sharpness of the images is hampered by the lack of shutter speed due to the low ISO settings.

ISO 800:

In these images the noise is extremely obvious in both versions, the light difference on the shop doorway and within the store add to the darkness and more obvious noise, while the areas in natural light are more acceptable in the full version the areas of shade and darkness are still obviously compact with noise.

This image shows a wide variation in colour and fine details, by using the high ISO I was able to shoot in placed around 1/1000 of a second however in this instance it was at a still effective 1/500th of a second, this enabled me to get a sharper image on not only the balls of wall and the colours but also the people in the background of the image.

Throughout this exercise and the course in general it has been a subject of how individual adaptations to exposure, via the aperture, shutter speed and ISO requires a reaction in the others, this is just as important when looking at ISO due to its large variation and effects on the overall exposure something which is explained visually with a exposure triangle.ExposureTriangle._V391966108_

Overall I found this exercise to positively reaffirm my understanding of ISO, its effects on the photograph and how its by product of noise can be a problem but also an artistic tool. The exercise illustrates the technical ability of my camera while also the choice of settings I used to produce the final image, the images are generally well rid of noise under a low ISO however it can be a real problem higher up even in an overcast to bright day situation, although a number of these images includes areas of shade. Previous to this exercise I very rarely used an ISO above 800 and would always try everything possible before I was to use that or anything higher in the future, I tend to use 100 or 200 in everyday shooting especially with street photography.



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