Trying to Pick a Lens

[flow]

I'm planning on renting a lens to use with our D40 for our upcoming vacation. I'm considering something along the lines of [h=1]Tamron AF 18-270mm f/3.5-6.3 Di II VC LD Aspherical DX for Nikon[/h]
I've never used one though ... is it a decent lens? It would be nice to have the full range and not have any switching out to worry about, but it would also be nice to not have problems with the images. Any experience with this one, or a recommendation otherwise?
What say you?

Also - Thinking it would be worth it to have it show up a few days ahead of time to give it a test run ahead of departure, or is that not worth the expense (since I won't have time to send it back & swap it anyway)?

 

[texkam]

Lenses with this wide of focal range do not produce sharp images.

 

[flow]

that's what I was afraid of ... back to the options I go.

 

[SeanE]

It may work well on your D40. The higher the pixel count the more lens flaws will show up. Can you get one locally so it can be returned? Or order it online from a reputable dealer that accepts returns.

I have a Nikon 18-200 VRII I'll sell ya.
It worked well on my D90 but not quite as good on my D7100.

So the D90 at 6mp may not have an issue with the 18-270.