Mastering the Art of Lens Testing – 3. Flare and Glare

Welcome to lesson 3, devoted to shiny ufo and ghosts that invite themselves in your photographs when a bright light is around the corner: Ghosting, Flare & Glare.


What it is

At every air-glass surface, some light is bounced back rather than transmitted along its intended path. Modern coatings help reduce the effect significantly (up to 10 stops of reduction) but never completely. As a consequence, some scatter of incoming light can occur and lower the contrast or produce unwanted parasite reflections.

The sun in the frame produces strong flaring with the Leica Elmarit R 19mm

Solar flare in a 19mm lens



What it does to the image

Flare is plainly visible, particularly in older lens designs, as a series of colourful geometrical patters (circles, ellipses, hexagons) aligned along a line originating at the sun or a bright source of light.

Leica R Macro Elmarit 60mm f/2.8 worst case flare at f/2.8

Flare at f/2.8 on a 60mm lens


Glare, on the other hand is simply a lessening of contrast due to the presence of unwanted light in shadow areas. It can kill off the impression of clarity you expect with the best lenses. The photograph above shows both glare (the trees should be darker) and flare (the UFO patterns at lower right).



How to test for it

Since this problem is due to scattering and parasite reflexions, you can make it appear easily in the following situation: point your camera towards the sun or a very bright light and, if possible include a large portion of dark areas (shadows, trees) where the artefacts will become very obvious, as above. Move the bright light source around the frame and slightly outside the frame (sometimes, the worse cases of flaring occur when the sun is just out of sight).

A very good lens will show no lessening of contrast and no weird shapes floating about in the image, as below.

No flare, no contrast reduction

No flare, no contrast reduction


How to fix it

Glare (lowered contrast) can be partially cured by increasing contrast. There is no escape from the effects or flare, though. Although some dig the look created by flare, it’s nearly impossible to remove when you try to.



F/5.6 – slight glare and a small flare pattern below the 3 dark-green bushes, on the right (small green streak)


In both cases, it is best to prevent than to cure. Avoiding very bright lights around the edges of the frame (using your hand, a tree trunk or a good lens shade for protection). Remember the effects of glare occur when the sun is just outside the frame, as below (in the second photograph, I blocked the sun with my hand).



Inefficient Lens shade


Sun blocked with my my hand


When you cannot avoid a bright light shining on your lens, closing the aperture helps reduce the effects of both. The image above is at f/8. Compare with the same lighting and (old) lens at f/2.8, above.


Leica R 60mm f/2.8 Macro Elmarit worst case flare at f/8

Flare at f/8 still present, glare greatly reduced



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  • Yeahhh says:

    Glare can add a nice mood to backlit images. But flare is normally a pain and needs to be avoided (unless you’re J.J. Abrams). The worst flare from my lens selection comes from the Voigtlander Heliar II 15mm f/4.5. It produces deep blue dots if the sun is right off the frame. And they’re very difficult to see in the viewfinder but ruin the whole picture. Hand-blocking never worked for me because my hand is then in the frame. Luckily, most lenses have great coatings and prevent flare and glare effectively.

  • Ricardo says:

    Thanks for this interesting publication.
    Unfortunately I have not received the lesson nº 2. Might you publish a link?
    Thank you

  • jean pierre (pete) guaron says:

    Oh dear – was I supposed to be running off at the mouth, again? I’ve gone backwards, Pascal, and added a comment on part 2 – chromatic aberration, which covers both that and part 1 – vignetting.

    On this one, I have a couple of observations.

    Sometimes a lens hood helps, sometimes it stops just short of killing off the source of the unwanted glare or whatever. Sometimes (like you, Pascal) I get there by holding a hand in front of the cam, so the shadow from the hand shields the front of the lens. But as Yeahhh says, you have to watch out in case the subtraction of glare comes at the expense of finding part of your hand in the field of view.

    I don’t normally have these issues, with the sun. I have a quaint old fashioned fear of peering at it, through a camera lens, and finding I’ve blinded myself – and someone once told me that it doesn’t do the innards of the camera any good, either. If “they” get to you early enough, it’s very hard to escape the residue of brainwashing – some adults even believe in Santa Claus and the Easter Bunny!

    But you do have to watch out for it, when you take shots with artificial lights in them. Glare or halos from them can enhance or ruin shots like street scenes at night.

    • pascaljappy says:

      Yes, fingers can be an issue. Think about what it’s like with a rangefinder 😉

      Most often, direct sun is less a problem than sidelighting, though. See recent review of Loxia 35 (but most lenses suffer in those conditions, including the mighty Otus).

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