Originally posted by sterretje In this case, OP comes from another system (Canon P&S) and therefore can't ignore the crop factor in my opinion.
You're joking, right? Translating the (obscured) focal length of a zoom on a 1/1.7" P&S sensor into APS-C terms is about meaningless. I'll argue that
formatfaktor misunderstandings lead many who are new to dSLRs to think that a 100mm lens mounted onto their Kx magically transforms into a 150mm lens. It sure fooled me the first time I put a 400mm lens on a half-frame SLR. Oh wow, a 600mm lens! I quickly learned my error; it's still a 400mm lens, but the image ends are sliced off.
I'll repeat: Crop factor is only significant to someone familiar with one format, who wants to mentally translate a lens's AOV between formats. And maybe not even then. In my film days I worked simultaneously with 135 half- and full-frame, 6x6cm medium format, and 9x12cm large (ha!) format. Not to mention 16mm spy cams. My peers and I didn't apply a
formatfaktor calculation to lenses; we just learned what each focal length would do with each format.