What are lens flares? It usually shows up as yellow-orange-blue streaks or geometrically shaped spots, or could even be an overall haze in a portion of the photo that actually reduces contrast, saturation, and masks details in the subject.
What causes flares? Bright light reflecting inside the lens… either from lens surfaces or from internal components in the lens pointing directly toward a brighter light source (usually sun, or bright light).
First choice, use multi-coated glass (higher quality lenses & filters) WILL help reduce flares, but no stock lens (that I’ve seen yet) is completely immune to it.
There are things a photographer can do to help control (and eliminate) ‘lens flare’
(whether still photos or video):
1) Use the Lens Hood… The wider the better… it help block the ‘top or side light’ which is a common cause of flares.
2) Use a CP (Circular Polarizer) OR ND (Neutral Density) Filter(s)… like sun glasses, the great ones can usually eliminate it with proper adjustment (turn the CP to enhance or detract from reflections & flares).
3) Use a ‘flag’ (or ‘barn doors’) – which is nothing more than a cover, usually rectangular in shape, that is above and out of the edge of the visible area of the lens… that blocks the ‘unwanted light’ (usually top or side light). In the photography world, these ‘flags’ are often referred to as ‘barn doors’ – which can help direct light when on a strobe, but also helps reduce flares when used on a lens.
4) ‘Close down’ you aperture (raise to a larger number which makes a smaller opening, such as f/16 or greater) and balance the exposure with either a slower shutter speed or higher ISO.
In many video cameras – including video through a still camera – aperture is often automatically set in video mode, and not user controlled… except in the higher end video cameras… so, other than a hood or filter, there is nothing you can do IN CAMERA. It must be ON camera, OR you’ll be forced to:
5) Change the physical angle of the lens to the flare.
Often, just a slight change in the direction you are pointing the lens is all that is needed. Shooting with the SUN or bright lights IN THE FRAME is often a really tough and challenging shot (one I really like doing, because it’s not an easy shot).
Bellows hoods are common place on outdoor video cameras. Like ‘barn doors’ they are usually much bigger, wider, and allow better blockage of a super bright top or side light.
Quite often, when I’m outdoors shooting into or toward the sun you’ll see my camera in my right hand, with my left hand totally off the camera, with my hand (or holding a note pad translucent reflector, car window shade, or a variety of other objects) a couple feet higher and to the left shading the lens from the flare… which merely reduces ambient lights bouncing around in the lens barrel.
Anyhow, hope that helps answer some questions about some ways I deal with lens flares.
If not, let me know.