See the Difference
All lenses are not the same; different lenses will not deliver the same image quality. Ensure you get the highest quality lenses to deliver the highest resolution, distortionfree imaging. The image below represents an actual side by side comparison of a Volk 20D lens compared with a non-Volk lens over a 2mm grid. The photo is not retouched.
Volk is known worldwide as the premier designer and manufacturer of the highest quality ophthalmic lenses. The first aspheric indirect ophthalmoscopy lens was developed by Dr. David Volk 50 years ago. This led to the patented, double aspheric designs of the 20D, 78D and 90D lenses, the leading standards in the ophthalmic industry.