By coincidence, I just got mine in the mail today for my W1 (I didn't order the 1.7x one though). Here's some comparison shots I quickly took with the W1 set to 5MP and Program. (Note I wasn't trying to be astetic, just did a quick shot from my backyard off a tripod)...
Here's how things looked with no lens attached. (5MP - f/5.6 - 1/400)...
Here's the Wide 0.7x lens. (5MP - f/5.6 - 1/400)...
Here's the Super Telephoto 2.6x, when I also zoomed my W1 to it's maximum 3x optical zoom (not digital). This madean actual zoom of 7.8x and is really impressive to me. (5MP - f/5.2 - 1/200)...
Note that the Super Telephoto 2.6x lens is kind of on the long side. As a result,you will see a circleif you do not zoom in your W1 to at least 2.4x. The subject matter isslightly overexposed as well because of this. (5MP - f/5.6 - 1/125)...
Since you have to zoom in so much on your W1,there really isn't much of a zoom range at all with the Super Telephoto 2.6x lens. I took a couple more shots to test the zoom range and found that it is only 6.24x to 7.8x without any trace of the circle you saw above, (at 5.46x thoughit's barely noticeable and on another cybershot like the P-100 may not be noticeable at all). Still, I'm impressed by the quality. Looks like this is the reason that Sony offer the 1.7x lens.
Because it's not as long a lens, I bet the Telephoto 1.7x offersthe range of zoom that is lacking from the 2.6x, (I'm guessing in the 3x to 5x range). I think having that range could come in handy. A local store has this lens. Maybe I'll buy it and try to duplicate what I did above.