Hi guys. any help with this would be greatly appreciated. I am trying to make a device like a periscope which is 100MM in length but has a diameter of 5mm. the viewing end of the periscope can be much wider to accomodate an eye optic, but the other end does need to retain the diameter of 5mm as it will be inserted into a cavity. This will be used to inspect an area of around 250mm square, but id like to see this clearly I am trying to work out which lenses would be needed for this, as it would be safe to assume that a convex lens would be needed for magnification, then perhaps a 45 degree angled mirror before then passing through another convex lens, unless concave would give a better field of view (dont think so?) As you can tell i dont know alot about lenses, other than a basic understanding of focal lengths with regards to CCTV lenses - presuming the same would be applied with the first lense being placed from the view finder. I am doing alot of guess work here trying to figure this out, and if there are any white papers, articles or your two cents worth you wouldnt mind sharing with me to help me figure this out, it would be gretly appreciated.