What implication does intrusion of the Spacer Tube Assembly have for images?
In our opinion, intrusion into the light path has little if any visual consequences. Intrusion occurs in the low power mode so the diffraction created by the obstruction of the Newtonian Spacer Tube assembly has no noticeable effect. In higher power modes where planet and Lunar high resolution viewing is undertaken, the spacer tube assembly should withdraw from the light path as focus is obtained since the mid and high power modes require the focuser to be racked outward. A 1.4X cell is available ($149) and a 3.2X cell is also available ($149). Use of these cells makes intrusion absolutely unnecessary in mid and higher power modes and the 1.4X cell creates a non-intrusive situation when using the low power 1.4X mode in the majority of Newtonian telescopes available today. A Newtonian is an obstructed optical system and the desire to downsize this obstruction as much as possible can create difficulties for our lowest power systems. Yet, almost any Newtonian will operate at our lowest po
