DSLR Training ISO (new speak for film speed).
This DSLR Training is on the subject of ISO. The following images are the same scene taken at different ISO’s
Image captured at ISO100, no noise in the picture
At ISO500, noise not noticeable
Taken at ISO25600, noise or grain is very noticeable in this picture
Taken at ISO4000, slight noise or grain in the dark areas of the picture
Film originally was rated as American Standards Association (ASA) this indicated the rating of speed the film recorded the image. To use film correctly, the camera had to be set at the rating of the film, i.e. ISO400 (ASA400). The disadvantage of film is that you couldn’t plan to shoot different locations in different lighting conditions. You could change the film speed but you had to note where you did in order to inform the printer when the film was printed. Unlike today this had limitations on what you could photograph.
Simply put ISO is the level of sensitivity of your camera to available light. A lower number the sensor is less sensitive than at higher numbers. With increased sensitivity you can capture images in low light levels.
ISO today
ISO has been in use since 1974 and stands for International Organization for Standardization. It is used for film and digital cameras with the same limitations for film being current today.
With modern digital cameras the ISO range is tremendous. They range from at the low end at ISO100 -ISO32000 or higher at the high end of the range. The big advantage is that you don’t have to change film to capture images in low light. The disadvantage is that as the ISO setting moves higher, you introduce noise (grain) into the picture. To help reduce noise and grain, software can be purchased to help keep this to a minimum. Not a problem at the lower end, but it is more noticeable at the higher end of the scale.
The video below made for DSLR Training shows the differences that the ISO makes on different settings.
Conclusion
The video demonstrates that noise is more noticeable the higher you have the ISO set. It is best to take your photo in the lowest ISO setting that you can achieve.
Assignment
Using the aperture setting, set your camera to ISO100 and use f8.0. Find a bottle of dark liquid (red wine) and photograph this is on your kitchen worktop near a window.
Repeat at ISO500 AND ISO4000. Download your images onto a PC. Look at your images at 100%, can you see the noise in the images?
When you have tried this, now go ahead and try different ISO’s up to 1000. Note where the grain noise becomes visible.
What to do next
If you would like to receive more of this series contact Martin here. Let him know if there is a subject you would like covered.
