Camera Lens Flare and Ghosting: What You Need to Know for Better Photography | Round Glass Review

Flare and ghosting are undesirable elements of lens performance caused when stray light passes through the lens and to the image media in ways that aren’t preferential from a technical standpoint. That means that light gets where it shouldn’t and it messes up your image.

Flare – According to reference A in the video’s description, flare occurs “when a lens is directed at a strong light source like the sun.” This results in unneeded light – the light rays that enter the lens but are not focused on the image area – to reflect “from the lens surface and the camera mirror's frame” which has an effect like covering the image in a blanket made of haze. This results in contrast loss and, as you likely know already, contrast and sharpness are interconnected like the tentacles of a dizzy octopus. Basically, flare causes a white, or lighter-toned area over some or all of the image and that area reduces contrast and sharpness.

According to reference B in the description, "veiling flare" occurs when light reflects off the lens, or other elements such as the lens barrel and mirror box, making part or all of an image appear soft or hazy.
So flare has many places where it can start – The elements’ optical surfaces, the elements’ ground edges, the lens housing, the aperture, the lens mount, the shutter box, the underside of the mirror, the bellows in a large-format camera, and especially your SLR to mirrorless adapters, etc. Basically, any surface between the image media and the lens’ front surface can cause flare under the right circumstances.

Ghosting – This is what happens when that hot date last weekend leaves you on read. It’s also the presence of colored shapes and rainbows in your images. Ghosting is a type of flare in that it has the same cause, but it manifests in a different way. According to reference A in the video’s description: “…the phenomenon known as ghosting occurs when light repeatedly reflects off the surface of the lens and is seen in the image. Reflections occurring in front of and behind the lens' aperture give the ghost the same shape as the aperture,” which means that when the ghost has the aperture’s shape or is a circle (generally because the lens was wide open) that the ghost is caused by stray, unneeded light passing through and interacting with the aperture.

Reference B adds this: “…also known as ‘ghosting flare’, [this] is caused by a strong light source being reflected repeatedly. It appears as a clear artifact that is usually located symmetrically opposite to the light source.” So we can infer from this that the number of reflections in the ghost corresponds to the number of optical surfaces interfering with the stray light. Coated lenses and different element shapes can reduce ghosting by reflecting stray light away.

Tips that can help you reduce or eliminate flare and ghosts:
1- Keep bright lights out of the peripheries of your images and also from resting just outside the frame.
2- Use a lens hood. With primes, a petal hood designed for the specific focal length is just as good as a tube. A generic petal or one not designed for the focal length is worse than a tube.
3- With a zoom (or if you have multiple primes) try a longer focal length as a tighter focal length can eliminate the problematic light source.
4- Keep your lens clean! Dust, dirt, smears, and grease can exacerbate flare and ghosting.
5- Buy multi-coated lenses (all lenses made today are multi-coated.) But if you’re looking at vintage lenses to use, uncoated and single-coated lenses do result in more flare than newer lenses.
6- Buy lenses with fewer elements (fewer elements mean fewer surfaces for internal reflections – this is one reason that I always include the lens diagram in my Round Glass Review videos, by the way.)
7- Embrace it! Sometimes flare’s washout and softness and ghosts’ rainbows and shapes can add an artistic element, especially in portraits.

Join this channel to get access to perks:
   / @davidhancock  

David Hancock's Amazon Author Page with Links to Select Camera Manual eBooks:
https://www.amazon.com/David-Hancock/...

My Instagram:
  / davidhancock  

Reference A:
https://av.jpn.support.panasonic.com/...
Reference B:
https://snapshot.canon-asia.com/id/ar...

"Suffer City Blues" by Suffer City used under active license from Epidemic Sound at the time of this video's upload.