Upside Down Telescope: Measure & Mark Points of Distance

Video Transcript

"The next thing we're going to do is put markings on the telescope to show us where each distance comes into focus. The way we do that is we put objects in front of the telescope and we focus on them by sliding the tube, the inner tube out and in until the object comes into focus. Now first we measure the distance of how far the object is from the telescope. So let?s say we're talking about the scissors which is about a foot away from the telescope. Once we see that it comes into focus we go ahead and we make a marking around the tube where it meets the outside tube and we know that that marking is let?s say one foot. When an object is one foot away it comes into focus. So that will be our one foot mark. And then we go ahead and take another object which is maybe three feet away and we go ahead and focus on that and then when it comes into focus we make a line where we've extended the tube and we make another line and we write on that the distance that we've focused on. In our case it would be three feet. So now we have markings going along the inner tube measuring different points of distance and this will help us know exactly where to hold the tube. How far to extend it or how far to insert it when we're trying to focus on a particular object at a set distance from the upside down telescope. And of course that if you're at a distance in between then you can always go in between the measurements. So now we've shown you how to make markings on the inner tube of our upside down telescope which will help us in knowing exactly how to focus our telescope on different objects at different distances."