I built a small Excel (TM) spreadsheet to calculate bellows compensation. It displays the compensation factor, compensation in stops, and the extension at which the compensation should be applied. I set the compensation increments in 1/3 stops. I can send you the spreadsheet if you wish.
However, because spreadsheets are such an easy way to spread viruses, you can build the spreadsheet yourself (with apologies for my marginal HTML skills): <table cellpadding="3" border="1"> <tr> <th> <th>A <th>B <th>C <th>D </tr> <tr> <td>1 <td>135 <td> <td> <td> </tr> <tr> <td>2 <td>135 <td>=A2/25.4 <td>=10^(D2/LOG(2)) <td>0.0 </tr> </table> Now, copy the second row and initialize cell D3, D4, and so on to 1/3 stop values. For example, 0, 0.3, 0.6, 1.0, 1.3, 1.6, etc. For a 135mm lens, for example, this is the table I get: <table cellpadding="3" border="1"> <tr> <th> <th>A <th>B <th>C <th>D </tr> <tr> <td>1 <td>135 <td> <td> <td> </tr> <tr> <td>2 <td>135 <td>5 3/8 <td>1.0 <td>0.0 </tr> <tr> <td>3 <td>150 <td>5 7/8 <td>1.2 <td>0.3 </tr> <tr> <td>4 <td>166 <td>6 4/8 <td>1.5 <td>0.6 </tr> <tr> <td>5 <td>191 <td>7 4/8 <td>2.0 <td>1.0 </tr> <tr> <td colspan=5>And so on... </tr> </table>
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