After some serious searching to no avail on the OCA website (which I was getting somewhat frustrated with) I realised that the 'grey texture' image that was apparently on the website under key resources was actually the picture printed on the opposite page - Doh! - However, I do believe that this could perhaps be better labelled!
Turkish Dance images.
In both grey texture image and turkish dance image - we are talking about detail verus noise.
Exercise: Your tolerance for noise
Find a situation that fulfills the following:
- Daylight indoors (outdoor sunlight would be too harsh to allow high ISO settings - while darker would involve long time exposures)
- A Combination of sharp detail and textureless areas (such as white walls) with some textureless areas in shadow.
Using a tripod take a series of indentical photos changing the ISO each time.
My camera covers the ISO range from 100, 200, 400, 800, 1600, 3200, 6400
I set my camera to AV and used my tripod for this exercise.
.JPG)
ISO 100
ISO 200
ISO 400
Slight noise appears, but does not detract from the image
ISO 800
Here noise is more evident
ISO 1600
I find that ISO 1600 is where the noise really becomes evident in the image, and becomes more so in the other 2 images ISO 3200 and 6400, where it is very apparent in the image.
ISO 3200
ISO 6400
The first two images taken at ISO 100 and ISO 200 used slower shutter speeds, so I am not going to use these images to compare. I have choosen images taken at ISO 400 and ISO 6400 to compare here are the results.
It is hard to see here, but extemely noticable on my larger screen the levels of noise from the left image taken at ISO 400 to the image on the right taken at ISO 6400.
Noise is probably the most common artifact in digital image capture (artifact being any part of the image that was processed and not from the original scene). Noise looks similar to graininess and both increase with the ISO sensitivity.
Freeman
M, Mastering Digital Photography, Dec 2010 Ilex
Press Limited, Pg 568
However they are not the same. There are 2 ways to deal with noise during shooting and also post production.
Noise can be surpressed during shooting images and can also be reduced afterwards in post production using suitable editing software.
100% ISO 400
100% ISO 6400
You can clearly see the noise from the 2 screen shots.
In house camera noise reduction facility would help reduce the noise, but this facility can vary between camera makes with some cameras not having the facility at all.
Post production software will also help eliminate the noise, although some require a series of different processes.