I posted last week in an effort to make up my mind on a 18-200 lens - Nikon or Sigma. Since that time I've had an unexpected bonus (cash) come my way and am thinking about something faster to stick on the D40X... or even perhaps a D300 with an 18-200 and then get some fast glass next year. I'm still thinking that I want something that will stay on the camera for 90% of the time. If I'm travelling and running around with my 1yr old girl I don't want to think about packing lot's of gear (on top of nappies, bottles etc.!). So, if someone were to come to your house/business today and take away all of your lenses and leave you with just one (whether you currently own it or not) for twelve months, what lens would you have? An unrelated questions. Essentially what is the difference on DX lenses? I'm aware that the sensor on DX cameras is smaller effectively giving you a 1.x crop and am aware that a DX lens won't work on a full format (D3/D700) camera but what happens if I put a 24-70 non DX lens on a DX camera? I'm guessing nothing, which makes me wonder why DX lenses exist at all...? What am I missing here? Darryl.