ISO in Digital Photography amplifies the light signal received from the sensor, unfortunately also the noise in that it is normally present gets amplified. We wrote the theoretical part about ISO in Digital Photography and Noise in Digital Photography. But considering from a practical point, it can not happen that; it is virtually a wrong technique to increase the ISO by compromising the quality. For composition purpose we have to increase the ISO in Digital Photography. And also actually we do increase ISO in Digital Photography specially with DSLRs. Then, there must be some arbitrary Acceptable values ??of ISO which will possibly not add any visible Noise.
ISO in Digital Photography : Understanding the Build Quality of the Sensor
A Full-frame DSLR, usually have a better noise tolerability level than a DSLR with APS-C Format Sensor. It is not because of the size or cost of the sensor but due to increase in spatial resolution. In easy words, the build quality actually contributes to this Noise factor. The minimum value of ISO can nowadays is 50 and the scale of the ISO is as follows: 50 100 200 400 800 1600 3200 6400. Those are listed beside, are the full-stop, digital cameras allow you to set ISO even at every third stop.
The situations in which we have more need to act on ISO are those in which the available light is poor. Take, for example indoor or outdoor evening photo. Because of the interdependence between the elements of the triangle of exposure, keeping fixed the ISO for correct exposure in these situations, we should:
- Increase the exposure time with the risk of getting a blurred picture or wake by moving objects
- Increase the opening, reducing the depth of field, which could not lead to the result that we want.
To avoid these two solutions, we can then raise the ISO, until the values ??of openness and exposure time are similar to those that we desire. But then, how you can always make good photograph in a low light shooting condition at the maximum ISO?
ISO in Digital Photography : Noise and Acceptable Values ??of ISO
The noise manifests itself in photographs primarily as a loss of sharpness and the appearance of colored spots, visible mainly on the dark areas. High noise levels can make a picture totally unusable. Fortunately, in some cases the noise can be exploited to our advantage. In fact, especially in black and white noise can sound like a old photos or as if it was taken on film.
The relationship between noise and ISO varies depending on the camera model. Nowadays there cameras are on the market that allows to get acceptable noise levels with very high ISO values ??(3200 for the Nikon D3s, one of the most advanced models). But this are extremely expensive cameras. The digital SLR of low-level easily produce excessive noise if they are already above the ISO value of 800. So if you do not own a camera of semi-professional or professional level, you should be careful to avoid the high values ??of ISO.
In any case, accumulating experience with our camera, we will become able to identify the correct values ??of ISO applicable to the situation in which we find ourselves. To do this, a useful exercise may be just what you take pictures of objects of different colors gradually trying to increase the ISO. Looking at these pictures on the computer screen we realize how much noise will be added to each photo by a particular value of ISO.