so, a 18 - 200mm DX lens is truly 18 - 200mm in a dSLR.

but, when i look on the nikon website, it says the 18 - 200mm DX lens is equivalent to 37 - 300mm in 35mm SLR format.

am i mistaken? i thought you didn't need to apply the crop factor to a dx lens?

The DX certification is more about optimizing the optics to avoid CA on glass smooth sensor as opposed to the somewhat textured film surface.

The sensors are actually little cup shapped things, and it's harder to get light to collect into the bottom of the cups at the extremes corners of the sensor, so there is often some fall-off.. The optical coatings help disperse the light correctly on the sensor.

The since the sensor is still smaller than a 35mm's imaging area, the crop factor still applies..Exception to the new D3.

They're saying that an 18mm lens on a DX body will give the same field of view as a 27 on a full frame body. Focal length is always focal length. However, the DX lens won't work (or won't work well) on a full frame body because it doesn't have a big enough image circle. The corners will be dark to black.