Originally posted by stanislav Most (not to say "all") APS-C zooms are usable on FF. The rule of thumb is that the it is usable from 1.5x the lowest focal length (since the FF is 1.5X bigger than APS-C, and zooms are made so that when you zoom in the projection circle is "inflated".
I have just three DA-type zooms with me (I left the DA18-55 at my home base) and here's what happens when I mount them on my ZX-M:
* DA18-250: Vignetting throughout its range; *least* vignetting at 18mm and 250mm
* Tamron 10-24: Vignetting from 10-14; clear from 15-24mm, as per your formula
* DA10-17: Similar to the Tamron -- vignetting from 10-15mm, clear at 15-17mm
I seem to recall a lens compatibility chart around here somewhere, indicating which DA lenses do and don't vignette on FF.