Camera producers keep overflowing market with new models, and DSLR cameras are increasingly popular. One advantage with a DSLR compared to point and shoot cameras is a large and bright viewer for accurate focus control. Interchangeable high quality lenses is the key to high quality pictures.
Although digital cameras are easy to handle, composition rules has not changed. A search for photography composition rules list several links.
Most cameras produced today (2010) are capable of producing high quality pictures, user error and low quality lenses might be the cause for low quality pictures. High quality lenses does not need to be expensive, an example from Nikon: Nikkor 50mm f/1.8Af-D (Approx 135 US Dollar) is a very sharp and perfect lens for portraits and landscape photo on a Nikon DX camerabody. Camera bodys without internal focus motor must use a AF-G or AF-S type lens for autofocus and metering. More information at bythom. On a FX body this lens is perfect as a normal lens. Nikon Dx camera sensor dimensions are about 2/3 those of the 35mm film format (29mm vs 43mm diagonal, approx.). Read more her: http://en.wikipedia.org/wiki/Nikon_DX_format. Nikon FX has same sensor size as 35 mm film. : http://en.wikipedia.org/wiki/Nikon_FX_format. DX camera bodys and lenses are generally lighter and less expensive than FX. A crop factor of 1.5 gives a 300mm lens the same view angle as a 450mm lens.
Nikon D70, Nikon 300mm f/4 AF-S. From a 6Mp D70 .nef file. 1/2000 at f4.
Image in Adobe Camera Raw with Rule of Thirds Crop Grid Overlay.
Further crop shows noise and artifacts. This is close to the limit for a 6Mp camera.
Buying a used Nikon D90 and used lenses will give you a very capable camera to start with. Combine this with a standard lens or with a zoom lens. Lenses with large aperture equal to f/2.8 or larger are suitable for low light and shallow DOF. Canon, Olympus and other have similar equipment.
Zoom lenses have a complicated internal focusing mechanism to obtain the variable zoom lengths; zoom lenses with a wide-ranging zoom area, generally have a lower optical quality than a zoom lens with a short zoom length. 18-200mm vs 24-70mm. Long lenses may need to be used with a small aperture to obtain good quality. Compare Nikon AF-S DX 17-55mm f/2.8 G IF-ED at above 1500US $ to the AF-S DX 16-85mm f/3.5-5.6G VR at 700US$ at www.nikonusa.com. The 17-55 f/2.8 is a heavy high-performance lens at premium price suitable for low light conditions, the 16-85 f/3.5-5.6 G is a consumer lens probably adequate for the new DSLR user. I have never considered buying one of these ,I prefer to use a lighter prime lens like 35mm f/2 and 50mm f/1.8 plus 12-24mm AF-S DX f/4 for wide angel scenes. These have been my preferred equipment for my previous Nikon D70 and D200.
About VR: Vibration Reduction extends usable range in low light condition. It is possible to have sharp images in low light condition with stationary objects. A short shutter delay in VR mode might be taken into consideration. VR does not have any effect on moving objects.
About filters: I prefer to have a high quality filter installed to protect my lenses from scratches and dust. Multi-coating helps reduce most surface reflections. B+W filters about MRC. I have not been able to detect any reduction in quality with filter on.
Nikon Best and Worst Lenses:
Rendering the print: Technical Paper, By Karl Lang