Tri-Bahtinov Focus Mask for Meade 8″ SCT, FP411T

Says it's for 8" Meade SCT, doesn't specify f/10 or later f/6.3. As a LX3 owner (Multi-Coated Silvered Optics Group owners unite!) I can assure you the outer diameter is too small and the inner diameter too large. When I centered it with spacers around the outer edge enough light made it through the inner gap to make the central star brightness overwhelm the diffraction spikes used to focus. I eventually used 1/4 in foam tape around the outside and inside hole to block the stray light and did achieve the best focus yet with my camera.