Formula for lens periscope I want to build a periscope. 
To my great surprise even after intense googling I could find little relevant information about periscopes anywhere on the internet.
Let's say I want to build a periscope with height h, apparent height h1, diameter d and viewing angle v. What other variables should I define for a periscope? 

Source: Wikipedia.
I am looking for a formula/manual/recipe for calculating the lenses and distances as well as any practical advice on building a DIY periscope. 
Thanks.
 A: What you are trying to do is build the combination is a terrestrial refracting telescope and a periscope.
As the design of the periscope is straight forward so you need to look up terrestrial refracting telescope to get some idea of the linear dimensions between lenses and the focal length of the lenses. 
There is some simple theory given at this website.
A search of the internet will give you construction details and suggestions for dimensions.
A: Assuming the two prisms are planar reflectors, there's no significant effect from them. If you do your refractor-telescope calculations by measuring the distances along the center of the light path, including the right angle bends, it should all work out. Then you put in the right-angle, planar reflectors (prisms or mirrors) and get the direction you want as an effect independent from magnification and focus.  The only other issue of the reflectors is their width relative to the angle of view you want to get.  But again, this is independent of the right angles - it's still just distance and width of the tube.
