1. 
   Varifocal
   A lens type that the focal length can be infinitely varied to give the exact image desired. It is similar to a manual zoom lens, except that a varifocal lens cannot be zoom tracked.
   Found op http://www.zoo.co.uk/~z0001325/Glossary.html
   
   
2. 
   Varifocal
   a spectacle lens which has graduated focusing strength from top to bottom
   Found op http://www.trayner.co.uk/Info/Glossary.html
   
   

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