I am far from a professional photographer, but I take it as seriously as possible while still referring to it as a hobby. I take mostly pictures of people at events and many of my baby son without flash in low light situations.
I had been using a Nikon D40x for 1 year and very early reached my limitation with that camera. The Nikon D40x has very nice image quality, but the camera's interface is not suited for a more serious shooter who wants quick single button or dial access to such shooting parameters such as white balance, shooting mode, metering mode, etc. I also felt very limited by the D40x not having an in-body focus motor that would allow me to use non AF-I/AF-S lenses (which are lenses without the focus motor built-in).
The Nikon D40x limitations were severe enough that I was about to consider purchasing a Canon 40D until the Nikon D90 appeared just in time.
PROS:
1. Fantastic set of separate buttons on the camera to control parameters like ISO, white balance, metering, autofocus, image quality, shooting mode, etc.
2. Two command dials
3. High resolution 920K pixel LCD screen (like the one on the Nikon D300)
4. 12.3 megapixel CMOS sensor
5. Low noise high ISO capability (for low light shooting) I can shoot ISO 1600 with good image quality with this camera, while on my D40x I could only shoot with ISO 400 and obtain acceptable IQ. I will even use ISO 3200 frequently with very usable results!
6. Separate top-viewing LCD screen in addition to the rear high res screen, to show shooting parameters constantly
7. In-body focus motor which allows the use of Nikon's non AF-I/S lenses, including wonderful and CHEAP prime lenses such as the Nikkor 50mm 1.8 (~$100 lens!)
8. Continuous shooting of 4.5 frames per second
9. Small size, although larger than the D40/D40x/D60, it is still substantially smaller in the hand than the D300/D3
10. 720p 24fps MPEG video shooting capability with incredible ability to use depth of field that I cannot achieve with my Sony High-Def camcorder.
11. Eleven auto-focus points (not as nice as the 51 points on the D300, but substantially better than my D40x with its 3 points)
12. GPS option
13. HDMI output
14. Enormous number of options to customize camera and shooting settings to fit your style of shooting
15. Fantastic image quality right out-of-box if you don't want to do any post processing
16. Terrific build quality
17. Top notch camera ergonomics (but this will be a very personal opinion that differs for each shooter)
CONS:
1. "Rolling shutter" phenomenon while recording video: The D90 CMOS sensor has the same problem that other CMOS video recorders have when recording video. If you move the camera, especially horizontally, you get a "jelly" or "rubberbanding" effect where the image wobbles significantly. It is nice to have the video features, which looks very sharp at 720p, but it is NOT a substitute for a video camera. If you use a tripod, and do not do quick zooms/pans, the video quality is excellent. Without a tripod, however, you may get nauseas watching a wobbly video. The sound is also in monoaural.
2. 1/200 flash synch: Not a problem for me, but it might be for you.
3. No weather sealing: This is found on the Nikon D300/D3 and even on similarly priced models from other camera companies
4. The buffer will fill up after about 8 continuous RAW + JPG (FINE) shots. This number differs depending on the shooting parameters that you will choose. If you shoot primarily JPG, the buffer seems to allow a very large number of continuous shots, but I have not quantified this for JPG only.
TIPS:
1. Get the FREE Nikon ViewNX software from Nikon's site as your 1st step in your workflow. This will let you examine your RAW images that you can process for either Nikon CaptureNX2 to do further RAW processing or just export to JPG for a JPG editor such as PhotoShop.
2. Recommend buying the Nikon CaptureNX2. It is a RAW converter (if you shoot in RAW) that will read the camera settings properly for export to JPG. Capture NX2, however, is not as slick as the Adobe products and Capture NX2 requires a fairly powerful computer, otherwise it can run pretty slowly on a PC > 3 years old.
3. If you use JPEGs out-of-camera, consider increasing the sharpness above the default 3 or 4. Nikon uses a very conservative sharpening default setting. Nikon has decided to change the default JPEG images to match the higher end D3/D700/D300 cameras which produce more neutral images. Consequently, the D90 images that are less punchy than the D40/D40x/D60/D80, so you may also want to turn up the in-camera saturation and contrast.
The Nikon D90 has all of the interface features that serious and even professional photographers need with wonderful image quality.Buy Nikon D90 Digital SLR Camera with 18-105mm AF-S DX VR Nikkor Lens [Outfit] + Nikon 70-300mm Lens + 4GB Card + EN-EL3e Battery + Case + Cameta Bonus Accessory Kit!
