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Message: <blockquote data-quote="etudiant" data-source="post: 3160719" data-attributes="member: 48052">Those big light buckets have to be fast, else the secondary sticks out into the stratosphere. Even so, just putting up their surrounding dome is an engineering challenge, especially as they are usually sited far from any industrial base.I might add that pretty much all of the 8 meter plus telescopes now use active optics, many even on the primary, which does improve their performance, but at a considerable cost.Seen that the binocular community is too conservative even to embrace Image Stabilization, despite its obvious huge benefit, it seems silly to be floating alternative optical schemes that offer little except added expense.I will now retreat to my foxhole.</blockquote>