Introduced in fall of 2008 as an update to Nikon's D80, the D90 high-end digital SLR captures 12.3 effective megapixels, and comes with various automated image optimization trappings. It uses a CMOS sensor to reduce noise in the image and maximize the gradation range, which is intended to provide as many visible subtle shades possible for objects in high light or dark shadow. Face Recognition and a 3D tracking mode enable automatic adjustments for exposure and white balance should subjects move to different backgrounds of lighting and color. Live View allows the user to shoot without looking through the SLR viewfinder with three contrast-detection settings (face priority, wide area, and normal area) to assist auto-focus on a chosen object in the frame. Nikon claims the camera's EXPEED processor allow the camera to record 4.5 fps continuously at its highest resolution.

The 3 inch LCD is 920,000 pixels, which is comparatively very high resolution for a viewfinder. The most notable new feature for the D90 is its ability to capture fully HD 720p video with sound – a rarity for digital SLR cameras – and video recording can operate with any of its light and exposure settings. SD cards account for storage, and connectivity includes a USB port and a mini HDMI port to connect with HDTVs.