Bests & Worsts Reviews from Amazon

I have a 10X mag glass that I bought from Amazon that I'm very happy with. However, the 30X glass, even though it has a 4 or 5 inch glass only allowed me to view about an area about the size of a U.S. quarter. VERY disappointed with this glass and am returning it. Perhaps it is a defective glass, I don't know, I just know it is unusable for me as I have impaired vision. I expected the magnification area size to be 4 to 5 inches in size, i.e. the same size as the glass.