It won't give u the 504mm range but don't forget, 504mm is the 35mm equivilant, if u use a D40, you need a 300mm lens on a slr plus superzooms quality of lenses tend to reduce significantly, if you want something similar for a slr try the tamron 17-250mm (correct me if im wrong). The main thing lacking about the fz 18 is that the max apperture is f/8. I know it should be smaller in slr comparison but it is not small enough for a good landscape shot. The noise on the D40 is also significantly better than the noise control on the fz 18. Live view is only used when yur in a difficult angle to to take a picture but majority of the pictures can be taken through the viewfinder. Plus the dynamic range of the sensor is equivilant to that of a compact. Unless yur doing bird photography I don't see the need for such a long zoom. Ive seen professionals taken insect photography using a 200mm on a slr and the pictures come out great. Im not a nikon user nor am I against Panasonic as I even used to own a fz-20 before but for the price gap, i seriously suggest u go for the slr instead.