Originally posted by k100d except the 60-250 extends to double the length
That seems unlikely!
The picture of the DA* 200, 300 and 60-250 show that the later sits between the size of the first two but is narrower. It probably needs to be that long for the 250 mm end.
DA*s are weather-sealed.
All the ones I've seen don't change length at all (except DA*16-50). This is necessary or there would be a big pressure change inside the camera/lens every time it is zoomed or close focused. The result would be seals being blown out or sucked in and sucking dust or moisture, thus defeating the purpose.
The down side of weather-seals is that the focus and zoom capabilities of the lens require more complicated movements of lens groups, rather than just being able to move all elements together as most primes can for focusing. As a result the characteristics of the lens can change dramatically through its focal range and zoom range.
Even the DA*300 which is a relatively simple design has very different focal length when close focusing than when at full stretch.