Review on Ajax Scientific Double Convex Bi Convex Spherical Science Education in Optics by Harley Franchetti

I bought this lens when the first one arrived (a different FL) and its focal length was less than half the advertised. Even though the focal length of this lens is only 22cm and not 25cm, I can get it to work. I would give this 4 stars as it is sharp and there is little to no edge to edge distortion. In terms of quality control, the second of these lenses I've ordered is exactly the same. The focal length is 220mm, so manufacturing in India is tedious, not quality control. So 3 stars. Great for frivolous stuff. Pretty good for a construction hobbyist with limitations. Not suitable for anything that requires any type of permit.