Many people evaluate the lens, either do not care or look at the price. But actually, there are a lot of lens parameters for us to evaluate the purchase.

First, the parameters of the lens can be divided into three categories: materials, face, film. Material constituting the lens substrate, and the substrate made of shape face, then to the lens coatings to enhance performance.

The materials, including: Abbe number, specific gravity, refractive index, UV protection, impact resistance, etc., which, when lens foreigners who choose the most attention, "Abbe number", this parameter is an indicator of the clarity of the lens, the Abbe the higher the number, the sharper. Refractive index of the lens thickness and the price, the higher the refractive index, the thinner the lens looks, the price is higher, but we need to note that the price does not represent the quality of the refractive index of the lens imaging, because the higher the refractive index Abbe number of this parameter will be reduced. That short, lens choice, choose a low refractive index and low power, highly select number of high refractive index.