HIGHER AND LOWER SENSITVITY

Exercise

• Use a busy scene to demonstrate the effects
• of taking a image at different iso speeds
• Compare and record the image results.

I used Borough Market as location the take the multiple
images at different speeds. The market was dark and at
iso 200 the reading at f3.5 was 1/20 sec so was difficult
to achieve a sharp hand held image.

The first images shows that at the highest image quality rating
of iso 200 the movement is blurred and depth of field is low
as the speed was slow at 1/20 sec. This means that no
movement could be captured sharp.

  

At iso 400 the speed is a little faster at 1/30 sec but movement

is still not sharp. The image quality is not compromised

too much as grain is less visible

At iso 800 the shutter speed is faster at 1/80 sec so

movement is sharper.Exposure levels also look more

balanced as more light captured in the foreground. Grain

is more visible but dose not compromise the final

image

At iso 1000 grain is now very visible/ Movement is

sharp I could have now chosen a smaller aperture to

increase depth of field. Exposure is also good.

At iso 1200 the grain is now very visible and is effecting

the final quality of the final image.

At the fastest speed iso 1600 grain is now compromising

the final image Movement is now frozen in time, but the final

image quality is impaired but the level of noise from the

graininess of the image.

My choice of image would be iso 800 where some of the

movement is captured sharp but the final quality of the image

is not too grainy.

This sequenced of cropped images demonstrate

the change in noise/grain levels at different iso

levels. The higher the iso the more noise levels

This is reflected in the same way film speeds

have higher grain levels the faster the speed

of film. This is because the film has more

light sensitivity grains at higher speeds.

 

Noise can be corrected in photoshop, which can help

reduce the level of pixilation/noise to improve the quality

of the final image

Below is an example of a grainy image before and after

correction in photoshop.

The following image was taken at night at iso 1600

hand held. In the first image you can see clearly

the grain/noise levels especially in the smoky

areas of the image.

In the second image the grain/noise levels have been

corrected and smoothed out by photoshop reprocessing

Grain can be a useful artistic tool and add to your final

image.All the below images have been shot at iso 1600

andI think the grain levels have added to the images

final level of atmosphere and composition.

Comments- When light is limited or compromised you can

increase film speed/iso levels on the camera to allow

for better aperture levels which increase depth

of field and can also freeze movement. The

compromise is that the faster speed the more noise

or grain you will get in the final image.

Grain can often add to your final image.

If you do not want the grain you can often correct

in photoshop