Can anyone tell me the distance from the optical axis to the nearest edge of the filter housing (see pictures)? I am considering mounting my STT-3200 + FW8G-STT + AO-8T on an ONAG-XM on a OS RH-250. Yes, I realize the ONAG-XM provides on-axis guiding and the latest MaximDL has multi-star guiding and NIR guiding is likely less affected by seeing, since the Fried parameter r0 varies as lambda^(6/5). Thanks! Jason