The first step is to choose the correct magnification and working distance to ensure that that you will work in ergonomically with your new loupe. Only with the correct working posture can you reduce eye strain, back / shoulder / neck tension, and stress-induced headaches. Furthermore, good ergonomics have shown to improve information processing and decision-making.
Low resolution, color distortion and flatness of the image should be avoided. Resolution is defined as the optical system’s ability to form distinguishable images of objects separated by small distances, or to recognize fine detail.
Looking with loupes at the testing objects and selecting an area of tiny details that can only be seen with magnification, is an excellent way to test loupes.
Chromatic aberration is an often-used term, referring to color distortion. Each color has a different wavelength and the first color that generally comes out of focus is blue. Quality loupes such as AdmetecVision’s do not show any blue haze just to the side of black lines on white paper.
Spherical aberration is another term that is often used. It refers to the flatness of the image. When viewed through quality loupes, an object will not exhibit any spherical aberrations as curved or spherical.
To evaluate loupes for their true optical performance, one must be trained to see the differences on such complex images. For most users, a simple piece of graph paper with black lines will suffice to reveal the difference between mediocre and high quality loupes.
The level of magnification used is mainly based on personal preferences. However, there are a few guidelines that are helpful for choosing the best magnification. The lowest comfortable magnification level must be selected, since this will provide the widest field of view. There is some commonly used and recommended magnification for loupes:
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