What are ISO settings, and how do they affect focusing? Which should I use?
ISO settings allow you to vary the sensitivity of the camera to light, in exactly the same way that you can use slow (low ISO) or fast (high ISO) film with film cameras. The great thing about digital cameras is that you can vary the ISO setting from shot-to-shot, or leave the camera to decide the setting itself depending upon light levels. ISO settings are a subject of constant debate on the various forums. At the heart of the matter is the fact that at higher ISO levels, especially 400, pics can appear noisy/grainy, just as they can with film cameras using fast film. Broadly, there are two schools of thought. The “perfectionists” insist on using ISO 50 or 100 at all times, as indeed do some of the reviewers when taking sample images. The downside is that forcing low ISO settings can open the aperture and create focusing problems, as well as possibly underexposing pics, and even (with the FZ1) making the EVF or LCD viewfinders difficult to use in very low light. The pragmatists, on the
