Made to the same aperture and focal ratio, and the same level of quality, FPL-53 and FCD 100, used with the best mating glasses available for each, should have about the same color correction.
Made to the same aperture, but one being with a slower focal ratio than the other, regardless of whether they are FPL-53 or FCD100, the slower scope would have better color correction than the faster one
The Scientific Explorer 127 FCD100s are f/7.5. Most FPL-53 telescopes are in this size range are f/7 or faster. Now even at 130mm, an f/7 FPL-53 telescope will have virtually color free performance with a polychromatic Strehl of .973, but an f/7.5 FPL-53 or FCD100 instrument would have closer to .99, so while both would be virtually color free, on paper, and in very sensitive tests, the slower scope would have the advantage.
So, the advantage in this case, with the assumption being that the the ES is f/7.5, and the other scopes were f/7, the answer is simply that the focal ratio is slower. If the FPL-53 scope was made to the same speed, the color correction would be about the same.
Edited by Eddgie, 16 April 2025 - 07:22 AM.