The Nikon D5100 DSLR camera is a slightly newer model than the D90, and is better for professional video recording because it has a higher resolution (4928x3264 pixels) compared with the Nikon D90 (4288x2848 pixels), records stereo sound and allows for in-camera video editing. However, the D90 has a longer battery life and faster response time. While the D5100 is for professionals, the Nikon D90 is aimed at the "prosumer" market.
Other than that, the two cameras are fairly similar.
|Nikon D5100||Nikon D90|
|Video Recording||Supports full HD movies of 1920 x 1080 at standard rates of 30 frames for second (fps).||Yes|
|Maximum Resolution||4,928 x 3,264 pixels (16.2 effective megapixels).||4288x2848 pixels|
|File Formats||RAW, JPEG, RAW+JPEG.||JPEG, RAW, RAW - JPEG|
|Resolution||16.2 Megapixel||12.3 Megapixel|
|Storage||Secure Digital, SDHC, SDXC compatible.||Secure digital, SDHC compatible|
|USB port||USB 2.0 Hi-Speed||USB 2.0 Hi-Speed|
|Weight||Approximately 510 g (1 lb. 2 oz.), camera body only.||1.5 lb|
|Continuous Shooting||Up to 4 frames per second.||4.5 fps|
|Minimum resolution||640x480 pixels||2144x1424 pixels|
|Sensor size||23.6x15.6 mm||23.6x15.8mm|
|Sensor type||DX-format RGB CMOS||DX-format CMOS sensor|
|Battery Life||Up to 660 shots with the Nikon EN-EL14 Lithium-Ion battery.||Approx. 850 shots|
|LCD Monitor||3-inch flip-out, variable angle monitor that can be tilted and swiveled.||Yes|
|Dimensions||128x97x79 mm||132x103x77 mm|
|Battery||Nikon EN-EL14 Lithium-Ion battery||Nikon EN-EL3e Lithium-Ion battery|
|Bluetooth||Optional addition||Optional addition|
|Size||5.0 x 3.8 x 3.1 in||5.2 x 4.1 x 3.0 in|
|LCD size||3-inch 920, 000 pixel||3-inch 920,000 pixel|
|White balance||14 modes, including auto and 12 presets and manual i.e. Auto, Cloudy, Flash, Fluorescent, Incandescent, Manual, Shadow, Sunny, Tungsten||Auto, Cloudy, Daylight, Flash, Fluorescent, Incandescent, Manual, Shade, Sunny, Tungsten|
|ISO ratings (light sensitivity)||auto, 100 - 25600||auto, 200 - 3200|
|Minimum shutter speed||Bulb+30 sec||30 sec|
|Maximum shutter speed||1/4000 sec||1/4000 sec|
|Exposure compensation||-5EV - +5EV with 1/2 or 1/3EV steps||-5EV - +5EV with 1/2 or 1/3EV steps|
|Maximum video resolution||1920x1080 pixels||1280x720 pixels|
|Minimum video resolution||640x480 pixels||320x216 pixels|
|Frames per second (fps)||25-30||25|
|Metering modes||Center weighted, Matrix, Spot||3D Matrix metering II, Center weighted, Spot|
|Focal length multiplier||1.5||1.5|
|Video sound||Stereo sound||Mono sound|
|Flash modes||anti red-eye, auto, fill in, off, rear curtin, slow flash||anti red-eye, auto, fill in, front curtin, off, rear curtin, slow flash|
|External flash type||Hot-shoe||Hot-shoe|
|Startup delay (seconds)||0.5||0.15 sec|
|Exposure modes||Auto, advanced scene, shutter-priority auto, aperture-priority auto, manual, quiet mode||Auto, advanced scene, aperture-priority auto, manual|
|Shutter lag (seconds)||0.114||0.065 sec|
The Nikon D90 features a 12.3 megapixel resolution, extended light sensitivity capabilities, live view and automatic correction of chromatic abberation. It is also the first DSLR to offer video recording. It has a built in autofocus motor.
The Nikon D5100 has a Nikon EXPEED 2 image/video processor and an in cameras High Dynamic Range mode. It has active D-Lighting, a D-Movie mode with autofocus, auto scene recognition, and a quiet shooting mode. It also has a stereo microphone input, and enhanced built-in RAW processing. It has no inbody autofocus motor, and so fully automatic autofocus requires the addition of another lens.
The D90 has fast startup and shutdown times, with about 0.3 seconds from turn on to capturing a picture, and 0.4 seconds to turn off. The buffer clearing time is 4 seconds after 20 large JPEGs or 1 second after 20 small JPEGs. It switches between play to record and to displaying images in 0.3-0.6 seconds, and the shutter response is under 0.2 seconds.
The D5100 has slightly slowly startup and shutdown times, with about 0.5 seconds from turning on to capturing a picture, and 0.1 seconds to turn off. The buffer takes 4 seconds to clear after 50 L/F JPEGs or 8 seconds after 13 RAW frames. When switching modes, it takes 0.4 seconds from play to record, 1 second from record to play, and 0.1 second to display a recorded image. The shutter response time is under 0.4 seconds for autofocus, 0.248 for manual focus, and 1.276 seconds for autofocus with live view.
The D90 is 5.3 x 4.1 x 3.0 inches and weighs 703g (1.6 lb) with battery.
The D5100 is 5.0 x 3.8 x 3.1 inches and weighs 829g (29.2 oz) including battery and lens.
Sensor and Image Quality
The Nikon D90 features a 12.3 megapixel sensor with ISO ranging from 100 to 6400.
The D1500 has a 16.2 megapixel sensor with a total pixel count of 16.9 megapixels. Its ISO ranges from 100 – 25600.
The D90 has a 3-inch LCD screen with 920,000 pixel display and a 170-degree viewing angle.
The D5100 also has a 3-inch LCD screen with 920,000 pixel display. It has a mounted tilt/swivel screen.
The D90 was the first DSLR to record video. It records 720p high-definition video with monosound. However, it cannot autofocus. Videos are limits to 2 GB file size and between 5 to 20 minutes for each continuous clip.
The D5100 also captures video. It can record HD video up to 19200 x 1080 pixels, with full-time auto focus and face detection. Videos have a maximum length of 20 minutes.
Nikon estimates that the D90 costs $899.95 for the body alone or $1199.99 with zoom lens.
The D5100 costs approximately $800 for the body only or $900 in a bundle with the AF-S DX Zoom-NIKKOR 18-55mm f/3.4-4.6G ED VR Lens.