When I first looked at this I thought it was pretty self explanatory. I thought this was the distance you need to be away from the target to get a full frame shot at the specified dimensions (47.25"x31.5")---This made perfect sense when I looked at the 10-22, But when I looked at the 135 F2L, this is what I got:



<table align="center" width="625" cellpadding="3" cellspacing="0" class="SpecsTable"]
<tbody>
<tr>
<td valign="top" class="SpecsTableCell"]<span style="font-size: 8pt;"]47.25" x 31.5" Subject Framing Distance</td>
<td valign="top" class="SpecsTableCell"]


135mm = 15.42'
189mm = 20.82'
270mm = 30.17'
</td>
</tr>
</tbody>
</table>



I first thought that the 3 different values were for different crop factors, FF, 1.3 and 1.6, but the math didn't work---So I am confused---I would really appreciate it if someonecould shed some light on this Spec:


Thanks,


Bob