Here is my 4.25" f/4.5 Newtonian being used as a finder scope for my 8" f/7 Newtonian. It is fitted with a Baader AstroSolar Film filter for solar observing. 

    I purchased my little 4.25" Rich Field Telescope (f/4.5 Newtonian) as a teenager from Coulter Optical for under $30 (back in the late 1970's). The kit came with the optics, a phenolic tube, and a simple eyepiece drawtube. It's small, lightweight, and fun to use. I've added a small plate to the bottom so that it can be fastened to a camera tripod. I also use it as a finder for my 8". In its finder scope mode, I use a 40 mm eyepiece giving it a whopping 3.3 degree field of view at 12 x (but with a 9 mm exit pupil!).