Hi Jason,

For tolerancing focal length, you can use either the Merit Function or User Script criterion. First, build your Merit Function with your focal length criterion. If this is the only operand in the Merit Function, then add your Target and Weight, and run the tolerance with Merit Function criterion selected. Now, the tolerance will optimize towards and report the value of the focal length only. 

If the Merit Function has multiple targets (such as focal length + MTF) then it may be more useful to set the focal length as a reported value instead of setting it as the image quality definition. This can be done by setting the criterion to User Script. Follow the steps in the Knowledgebase article “How to get any optimization operand value in the tolerance report” for more information.