The Nikon D80, a 10-megapixel digital SLR introduced in 2006, was a popular "prosumer" (professional/consumer) model in the Nikon line. It was replaced in 2008 by the D90, a camera that borrowed much of the technology of the professional level D300, and added HD video capability as well. The D90's 12-megapixel sensor was a definite upgrade over the D80. The D90 also borrowed the D300's ISO performance, significantly upgrading the D80.
What is ISO
ISO refers to the sensitivity of the sensor in the camera to light. The term is a holdover from the film days, when different speeds of film were used depending on the available light. Lower speed films (64, 100, 200) are used for daylight, and higher speed films (400, 800, 1600) are used indoors.
ISO on a digital camera
ISO on a digital camera works by boosting the sensors receptivity to light. However, as the sensitivity is increased, the image can get significantly noisier and grainier.
D80
The Nikon D80 has ISO settings from 100 to 1,600, plus additional settings up to 1 exposure value over 1,600 in steps of 1/3. Settings on the D80 include prime ISOs of 100, 200, 400, 800, and 1600. The values over 1,600 are H 0.3 (ISO 2000), H 0.7 (ISO 2500), and H 1.0 (ISO 3200). In addition, the main ISO has steps of 1/3 value in ISO, so there are ISOs of 125, 160, 250, 320, 500, 640, 1,000 and 1,250. the H ISOs are generally considered "emergency only" settings due to the high levels of noise.
D90
The D90 has the same ISO settings as the D80, except above 1,600, instead of a boost, it uses the technology of the D300 to get clean ISO values of 2,000, 2,500, and 3,200, and a boost setting to get values of 4,000, 5,000, and 6,400.
In practice
Because the D90 can shoot noise free images up to ISO 3,200, and have noisy but usable boosted ISOs up to 6400, it is a significantly more powerful and flexible low light camera than the D80. Boosting ISO up to 1,600 or even 3,200 can allow a photographer to select far faster shutter speeds in normal indoor lighting for shooting sports and freezing the action, or shoot concerts at slower shutter speeds.
Tags: digital camera, shutter speeds, speed films