I've been asked why
giant binoculars are so prone to
collimation problems. First, let me say that misaligned binocular prisms and the resultant loss of image quality or, in worst case examples, double images, are rarely an issue with high grade
astronomy binoculars. You are much more likely to have alignment (collimation) issues with inexpensive
giant binoculars. Why? Less expensive binoculars have lighter weight housings, which tend to flex under the load of big objectives. This flexing eventually works the prisms loose. Inexpensive giant binoculars also cut corners when it comes to securing the prisms in the housings. Sure, some inexpensive astronomy binoculars feature collimation adjustment screws as a solution, but a better answer is to buy a higher grade of astronomy binocular, not just for the sake optics, but for the sake of reliability.