There’s a lot of talk about cameras and, consequently, lenses get overlooked. With competing priorities when you buy a lens, here are some things that could affect your decision on which lens to buy. In photography, there is always a payoff.
Whatever advantage a particular choice brings, there will be a disadvantage. Also, any rule in photography should be treated as if we mean “as a rule,” and not a hard fact. There are always exceptions.
So, as a rule, if we consider we want it to help us get the best quality photo possible. So, we’ll start by thinking about what we want to avoid. An aberration is a lens defect that prevents the lens from forming a perfect image.
Often, this will mean that some of the light entering the lens will be focused too near or too far from the focal plane. Sometimes this may be light of a particular wavelength, so light is split, causing colored fringing most visible around high-contrast edges. That effect is called chromatic aberration.
Visible lens flare is an aberration where light enters the lens and bounces off internal surfaces. This is usually unwanted. However, it can be used as a creative effect.
Think of JJ Abrams’ films and the horizontal lines of lens flare resulting from the anamorphic lenses used in cinema. Good quality lenses have coatings on the internal lens elements that prevent light from being reflected from their surface. There’s a second kind of lens flare where the image's contrast is reduced by the light falling .