Lens flare

While looking at some pictures I took a year or so ago with the unlovely 28-90mm kit lens on my Rebel Ti, I noticed several prints that were hazy with low contrast and a blue-purple tinge. I think this is referred to as 'veiling flare'. Most of these pictures have a significant ammount of sky in the background but the sun doesn't seem to be anywhere near the frame. I was under the (possibly mistaken) impression that lens flare is usually caused by a point source of bright light in or near the frame. Is it equally likely with a diffuse light source (sky light)?

Yes: Lens Flare can present without the point source tell-tales.

 

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Without an example to look at, I will take a stab and suggest there might be two issues:

 

1. Lens Flare (hazy, low contrast)

 

2. Atmospheric Haze (Blue Purple tinge)

 

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Sometimes referred to as ``veiling flare`` (to differentiate from the little pentagons, hexagons, heptagons and octagons), but I have never separated the two: I just refer to both as ``Lens Flare`` and it having two different presentations.

 

The ``veiling flare`` I understand, is presentation caused by the light bouncing inside the lens and subsequently filling the shadow area, denuding shadow detail of dynamic range and thus flattening contrast, and, obviously reducing the overall brightness RANGE of the image.

 

This can happen on a bright day and also an overcast day: and if it is ``Veiling Flare`` in your case, it is possible, the intense brightness from the large mass of sky, just bounced into your lens . . . and bounced around.

 

This ``veiling flare`` can actually be REDUCED in directional lighting, by not allowing the directional light hitting the front element of the lens.

 

Because ``veiling flare`` tends to be uniform across the image, it has a more effect on the dynamic range of the shadow and mid-tones than, the highlights, which I have seen misinterpreted as underexposure.

 

Obviously, flare is reduced by using a lens hood and not shooting into the sun, but it is fact that some lenses are less susceptible to flare than others.

 

In regard to the lens itself, flare is reduced by better coatings; by good blacking and baffling; and by simpler lens designs with fewer glass / air surfaces.

 

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An example, from you, would assist in a correct diagnosis.

 

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As an example of extreme lens flare (including veiling flare) see below.

 

The image was taken with an EOS20D using the 18 to 55 kit lens: set at FL = 18mm and shot at 1/200 @ F13 @ ISO200, HandHeld, Manual Mode. There was no adequate lens hood used, and even if it were, it would have been useless.

 

The original had correct exposure on the skin tones, but overall extremely low contrast, (trust me not much contrast at all) because of all the stray light, substantially nuking all the shadow and mid detail. And there is a perfectly placed Flare Hexagon, which sears the main subject.

 

This image has been Post Produced to the point of Decay, to get some contrast from the original (bright), but low contrast image: not the best solution IMO.

 

Also, although good for many purposes, if used within its limitations, the 18 to 55 kit lens is not the most Flare Resistant lens, though, in all fairness, its use in this mage was quite severe. I think perhaps the lens you used, is not one of the most Flare Resistant lenses, either.

 

WW<div></div>

Lens flare are present in the pictures only when frontal surface of your lens see (is exposed to) a strong light source. A diffuse of diffuse will be in photography... did you see ever, in cinema making off, how they protect the frontal lens from any kind of direct light source (we talk about 'countre-jour', like in your photo)

William, thank you for the clear and detailed explanation. Unfortunately, I am unable to post a sample picture at the moment as I don't usually ask for the negatives to be scanned (the 1800x1200 scans provided by most labs being of limited use for post-processing). I will however get some scans done so that I can post some examples in a few days.

 

In the meantime, I will be taking my new 28-105/3.5-4.5 to Bali next week. Being only half-way through my first test roll of film with the new lens, I'm slightly apprehensive about flare in view of my previous experience with the 28-90 kit zoom (I've been using the 50/1.8 for the last few months without any significant issues). I am waiting for my EW-63 hood to arrive but am not sure whether it would work any better than the rather shallow EW-60C (on the kit zoom). I would certainly appreciate your advice.

> I am unable to post a sample picture at the moment <

 

Yes I anticipated that, and that is why I posted an example, (a very extreme example), for your information.

 

> I would certainly appreciate your advice. <

 

I think you need to carefully look through the viewfinder for any flare: which is difficult when you are in bright light. Also, on the smaller sensor cameras, the viewfinder is not that great in bight ambient light: but push your eye hard against the eyepiece or get an eyecup or shield your eye / viewfinder from light coming in from the side.

 

When composing the scene, without an adequate lens hood, often you can use the free hand (usually the left hand) to shade or to hold a piece of black card, as a shade.

 

It is always handy to have an A4 piece of black card and A4 white card, a few elastic bands some GAF tape and a few large garbage bags . . . they all have multiple uses, cost next to nothing, are light weight and easy to carry.

 

Also, be very aware of where the light source(s) are in relation to your lens: once you have a good accurate clear image in the viewfinder move the camera around and note any flare points as the image changes contrast: maybe difficult to do, but with practice certainly possible to minimize your losses.

 

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I was looking for the Photonet thread where this photo (below) was given as an example.

 

If I recall accurately, the question was very similar to yours. I cannot find the thread but the image is a typical example of what you refer to as `` veiling flare ``: note the extreme low contrast, even after, (I think), the photographer has attempted to lift the contrast in post production.

 

If this is similar to what you are getting, then yes: it is lens flare.

 

Good luck, enjoy Bali.

 

WW<div></div>