Here are some comparison shots using a 1Dmk2 with 1.3x crop factor.  <hr><br><Br>

<TABLE WIDTH="90%"  CELLSPACING="1" CELLPADDING="4" BORDER="1">

<h1>Lens test @ 20mm Center Crop</h1> 
<TR>
<TD>Simga 12-24mm f/4.5 - 5.6 @ 20mm</tD>
<TD>Sigma 20mm f/1.8 </td>
<TD>Canon 17-40mm f/4L @ 20mm</TD>
</TR>



<TR>
<TD><img src =  "http://etischer.com/1dmk2/lenstests/20mm/full.jpg">
<br>full image </TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/doover/cen/HP8F0542.JPG">
<br>Sigma f/1.8</TD>

<TD></TD>
</TR>




<TR>
<TD></TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/doover/cen/HP8F0543.JPG">
<br>Sigma f/2.5</TD>

<TD></TD>
</TR>






<TR>
<TD></TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/doover/cen/HP8F0544.JPG">
<br>Sigma f/3.5</TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/cen/HP8F0516.JPG">
<br>Canon f/4</TD>
</TR>




<TR>
<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/cen/HP8F0511.JPG">
<br>Sigma f/5.6</TD>


<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/doover/cen/HP8F0545.JPG">
<br>Sigma f/5</TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/cen/HP8F0517.JPG">
<br>Canon f/5.6</TD>
</TR>







<TR>
<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/cen/HP8F0512.JPG">
<br>Sigma f/8</TD>


<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/doover/cen/HP8F0546.JPG">
<br>Sigma f/7.1</TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/cen/HP8F0518.JPG">
<br>Canon f/8</TD>
</TR>




<TR>
<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/cen/HP8F0513.JPG">
<br>Sigma f/11</TD>


<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/doover/cen/HP8F0547.JPG">
<br>Sigma f/10</TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/cen/HP8F0519.JPG">
<br>Canon f/11</TD>
</TR>



<TR>
<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/cen/HP8F0514.JPG">
<br>Sigma f/16</TD>


<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/doover/cen/HP8F0548.JPG">
<br>Sigma f/14</TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/cen/HP8F0520.JPG">
<br>Canon f/16</TD>
</TR>


</table><br><br><hr>









<TABLE WIDTH="90%"  CELLSPACING="1" CELLPADDING="4" BORDER="1">

<h1>Lens test @ 20mm Edge Crop</h1> 
<TR>
<TD>Simga 12-24mm f/4.5 - 5.6 @ 20mm</tD>
<TD>Sigma 20mm f/1.8 </td>
<TD>Canon 17-40mm f/4L @ 20mm</TD>
</TR>





<TR>
<TD><img src =  "http://etischer.com/1dmk2/lenstests/20mm/full.jpg">
<br>full image </TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/doover/edge/HP8F0542.JPG">
<br>Sigma f/1.8</TD>

<TD></TD>
</TR>




<TR>
<TD></TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/doover/edge/HP8F0543.JPG">
<br>Sigma f/2.5</TD>

<TD></TD>
</TR>






<TR>
<TD></TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/doover/edge/HP8F0544.JPG">
<br>Sigma f/3.5</TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/edge/HP8F0516.JPG">
<br>Canon f/4</TD>
</TR>




<TR>
<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/edge/HP8F0511.JPG">
<br>Sigma f/5.6</TD>


<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/doover/edge/HP8F0544.JPG">
<br>Sigma f/5</TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/edge/HP8F0517.JPG">
<br>Canon f/5.6</TD>
</TR>





<TR>
<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/edge/HP8F0512.JPG">
<br>Sigma f/8</TD>


<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/doover/edge/HP8F0545.JPG">
<br>Sigma f/7.1</TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/edge/HP8F0518.JPG">
<br>Canon f/8</TD>
</TR>



<TR>
<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/edge/HP8F0513.JPG">
<br>Sigma f/11</TD>


<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/doover/edge/HP8F0546.JPG">
<br>Sigma f/10</TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/edge/HP8F0519.JPG">
<br>Canon f/11</TD>
</TR>




<TR>
<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/edge/HP8F0514.JPG">
<br>Sigma f/16</TD>


<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/doover/edge/HP8F0547.JPG">
<br>Sigma f/14</TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/edge/HP8F0520.JPG">
<br>Canon f/16</TD>
</TR>



<TR>
<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/edge/HP8F0515.JPG">
<br>Sigma f/22</TD>


<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/doover/edge/HP8F0548.JPG">
<br>Sigma f/20</TD>

<TD><img src = "http://etischer.com/1dmk2/lenstests/20mm/edge/HP8F0521.JPG">
<br>Canon f/22</TD>
</TR>


</table><br><br>