This is a listing of changes in the design form or the design approach that may significantly improve or change a lens design. Many changes can be incorporated without a major change in the system’s power or magnification. They can be introduced blindly because they are expected to be beneficial.* Note that most of these changes require additional intervention, i.e., complementary changes to the balance of the system to restore (and hopefully improve) the design. In no particular order, the suggestions are:
1. Bend an element. Change its shape but maintain its power.
2. Add a field flattener or a concave surface close to the image.
3. Remove a weak element ...