There are pros & cons to choosing prime over zoom lens. Generally primes can be sharper edge to edge, faster and provide better resolution.  These differences have narrowed over the years.  Current zoom lenses are pretty close in image quality (remember it depends what specific two lens you’re comparing…a very good zoom beats a lower quality prime).

A lesser known advantage of primes however is the ability to render great images when shooting into the sun (either directly or when partially obscured by an object).  The image above was taken with a Canon L Series Zoom (17-40mm @ F16).  Great lens…however you’ll notice that there is considerable flaring around the sun.  That’s detracting from an otherwise good image.

Compare the image below taken on the same Canon Full Frame back and a Zeiss Prime 16mm (also at 16mm). Very little lens flair and much better defined sun.

This time using a Zeiss 16mm prime

This time using a Zeiss 16mm prime

Why the difference? When shooting into the sun: light bounces around inside the lens, off of the various elements inside. To dumb it down…prime lenses have fewer elements…and offer fewer ops for light to be reflected inside your lens. The advent of new lens coatings has help reduced flair additionally.

Bottom line: Shooting into the sun…grab a prime.