Many discussions on Cloudy Nights focus on "Which is better?." An occasional topic is how fluor-crown glass, FPL53, compares to synthetic crystal fluorite, CaF2. Fortunately, Vladimir Sacek offers examples at http://www.telescope...po_examples.htm - nicely answering the question.
Design #15 is for a FPL53 doublet (ZKN7 and FPL53) and design #16 is for a CaF2 doublet (K5 and CaF2), allowing for an easy comparison. Both are 100mm f/10 instruments.
Designs #18 and #19 allow comparisons of triplets, with the first featuring a ZKN7/FPL53/ZKN7 triplet and the second a K7/CaF2/K7 version. Both are 140mm f/7 telescopes.
Note, especially, the polychromatic Strehl in the last column for each design.
Clear skies, Alan