Sorry for the gap between posts. I’ve been away with work and I never seem to have the time offshore to sit and blog. Anyway I digress. Between my first SLR and my first DSLR I had a variety of compact cameras as thats what fitted my needs best. I do recall getting a Minolta Super Zoom (well super for the time) which was quite sophisticated. This was of course still in the film era (it hasn’t actually ended) so would require rolls of 35mm film. It was then that I started playing around with different ASA values or ISO as its also known as. Its so easy these days to just switch the ISO setting to something else or leave the camera to set it automatically to a pre set threshold that we seem to forget that in the film days once you had loaded your film and set the ASA on your camera accordingly that was that.
So as I say I started using different ASA values of film depending upon what I was shooting. For the beginners out there ASA was defined by the American Standards Association and based on a lot of work by Kodak. this was way back in the 40’s so its been around a long time. The number relates to the sensitivity of the film to the available light. The higher the number the more sensitive the film to the available light. Relatively insensitive film, with a correspondingly lower speed index, requires more exposure to light to produce the same image density as a more sensitive film, and is thus commonly termed a slow film. Highly sensitive films are correspondingly termed fast films. In both digital and film photography, the reduction of exposure corresponding to use of higher sensitivities generally leads to reduced image quality (via coarser film grain or higher image noise of other types).
The ability of modern DSLR to take fairly clean images at low light levels is astonishing and when you get to the Pro end these cameras can as I often quote to people “See in the Dark”! I can push my D4 to very high ISO levels before encountering any serious noise issues.
Obviously the ability to push your “film speed” up on the fly is very useful as it can allow you to keep shutter speeds up and use a more user friendly aperture.
More on that tomorrow