Exercise: Your Tolerance for Noise
Find a picture situation which fulfils the following criteria: –
- Daylight indoors (for the amount of light – outdoor sunlight would be too bright to allow high ISO settings, while much darker would involve long exposures).
- A combination of sharp detail and textureless areas (such as a white wall), with some textureless area in shadow.
Set the camera on a tripod; start by making a series of identical images, changing the ISO setting from one to the next between each image. Cover the whole ISO setting range of your camera and make notes about the results.
My setting for this exercise was in the communal lounge of the residential complex I live in. The walls are painted a creamy magnolia sort of colour and the wall opposite the French windows fits the requirements of the brief.
The following are the results both full-sized and detail images to show the effects that are being tested in this exercise.
When these images are viewed at a much greater magnification than standard size, the noise starts to become apparent, when viewed closely, at ISO 400. It becomes noticeable, with just a short viewing, at ISO 800 and is extremely apparent from ISO 1600 onward. In darker areas noise become more apparent at even ISO 200 and by ISO 800, edge detail is beginning to be lost.
To differentiate noise from detail, as in the ‘Grey Texture’ image on the OCA Core Resources site, the photographer needs to make sure that they’ve had a very good look at things like clothes and the detail of intricate objects to ensure that they can reduce noise in post-processing without reducing it so much they lose detail.
I was already reasonably au fait with the concepts behind this learning beforehand, what I have gained is a sure knowledge that whatever the circumstances I will always use the lowest ISO setting possible to obtain the results I want to keep noise at the lowest level. This will make post-processing decisions about noise versus detail less subjective.