Thank you for your great explanation on this topic.

So in essence, they mark the protcut as 18-55mm in accordance to 35mm frame. Need a constant to compare against, since there if no real standard size for CCD.

I now understand.

Thank you
Derrick.

Hello,

I'm new to the digital slr world. I recently purchased a *ist ds kit. It included the Pentax smc 18-55mm F3.5-5.6 da lens. Since this lens is made for digital slr use, is it really 18-55mm focal length when used with the *ist ds camera? Or is that focal length multiplied by a factor of 1.5 to make it an 27-83mm ? Becasue of the image sensor (CCD).

Thanks,
Derrick.