One Photographer's Take on Flare

By William Schneider

Most photographers have a sense of what flare is, especially specular flare. Specular flare is distinct enough that even non-photographer recognize it. This kind of flare is so prevalent that some software programs have a filter to add it in varying degrees to any picture as a special effect.

Depending upon the individual lens used and the position of light sources in the frame, specular flare can range from enchanting to downright ugly. The common cross-star filter attached to the front of an otherwise good lens produces rays from each light in the scene, and it's considered a pleasing form of flare. However flare can get ugly too. Below is an slide made using an older 35mm ƒ/1.8 Minolta lens. Look in the lower left of this photo to see a grotesque flare shape that detracts from the quiet scene.

The odd-shaped specular flare in the lower left detracts from this photo.

More insidious is veiling glare. With it, there are no obvious specular shapes in photos, just a lowering of overall picture contrast. It often goes unnoticed. Shadow contrast is especially hit hard. Dark tones are swamped with unwanted light from flare, artificially lightening them and reducing contrast.

Look in the dark tones for the effects of veiling glare.

In the old film days, using UV filters on the front of the lens for protection was hotly debated. Some said that it made no difference in picture quality, others swore that filters hurt the picture. What was often missing in these arguments is whether the filters were optically coated or not, and what kind of films were being used. B&W films have a tremendous ability to record information deep in the shadows where veiling glare lurks, but slide films can't reach down as far, and that matters. In short, if the sum of veiling glare and shadow exposure is below the film or sensor threshold, the effects won't be seen. I suspect that modern digital cameras fall somewhere in between B&W and slide films in how they record the deepest shadows.

The lens used for this 4x5 photo has low flare, although there are still indications of it around the street lights. To minimize flare and maximize contrast in the shadows, no filter was used and a lens hood protected the lens from a nearby street light above the frame.

I once did some experiments to see how Tri-X negatives fared in three different scenarios—using a lens hood to shade the lens from the sun, using a bare lens, and attaching a non-coated UV filter. (A non-coated filter reflects about 4% of the light that hits each surface. A multi-coated filter will reduce reflections to around half a percent, an 8x improvement.)

Shooting into the sun in a flare light torture test.

I tested two different Nikon lenses—one was a Nikon 45mm ƒ/2.8 P "pancake" lens that has only four elements in three groups. Having few glass/air surfaces, it should be naturally flare resistant. The other lens tested was a Nikkor 50mm ƒ/1.4 AIS, with seven elements in six groups, and obviously more prone to flare. I photographed the setup below, exposing for the gray card sitting atop the cardboard box containing the flare target. The flare target was a printout of type in various shades of gray from 0% (paper white) to 95% (very dark gray) all against a black background.

The first comparison negatives from the 45mm pancake lens in this test clearly showed a difference between using a filter and the bare and hooded cases. With this flare-resistant lens, very little change was noted between using a hood or just a bare lens as you can see in the animation below. That the lens hood didn't make much difference is not really a surprise here.

Animated comparison of cropped negatives from the 45mm pancake lens.

The next picture shows the flare performance of the 50mm ƒ/1.4 lens using the same configurations of UV filter, bare lens, or lens hood.

Animation showing scanned Tri-X negatives from the 50mm f/1.4 lens.

It's easy to see that the non-coated filter diminishes contrast in the negative with both lenses, and that the lens hood offers the most improvement for the most flare-prone lens. I suspect that zoom lenses, having many more elements than my 50mm ƒ/1.4, would benefit the most from a lens hood.

I also suspect that the increasing dynamic range of newer digital camera sensors will re-ignite the filter vs. no filter argument. As newer cameras begin reaching deeper into the shadows for information, the effects of flare will become more evident.

Filters are useful for protecting lenses, but substantially-made lens hoods offer a lot of protection while  improving performance. That’s something no filter can do. Wide-angle lenses are special problem because their lens hoods are too shallow to provide much protection. A filter is wise here, especially if the filter has an anti-reflection coating to reduce flare effects. Quality optical coatings do help.

Use protective filters when needed, but recognize troublesome situations to know when to remove them. Shade the lens from oblique lights using lens hoods, or even your hand if you can. Don't forget the old trick of positioning bright lights in a scene behind branches, people, etc. to reduce all types of flare.

Using a low-flare lens, removing filters, and hiding the direct light source are ways to reduce both specular and veiling flare. Note the substantial detail in the shadowed side of the tower.

No lens or camera is completely free of flare, but learning what you can and can't do is part of understanding your equipment.

Bill

ADDENDUM: As I mentioned in the story, I don't think that it's wise to go to one extreme or the other regarding filter usage. There are times where the pluses and minuses should be weighed. I'd use a filter, for example, when shooting a muddy motocross race close to the track, or in blowing sand and surf.

If there's an expectation of danger to the lens itself, by all means, use a filter. You'll also have to factor in how you treat your own equipment in the course of working. In short, use reason.

Several comments were made by users who have coated filters. Not all filters coatings are equal. In the photo below, I arranged a collection of filters in increasing coating effectiveness from left to right.

At the far left, I placed a piece of plain glass for comparison. I also placed a stainless steel ruler in the scene to show that the reflected illumination (from a white cathedral ceiling lit by a softbox) was very even.

The cheapest uncoated filters reflect as much light as the plain glass. The middle filter has a single coating. At the far right is a B+W multicoated filter showing exceptional performance. However, be prepared to spend a some money on a filter of this quality.

Bill Schneider teaches in the School of Visual Communication at Ohio University.

Additional reading: Mike's take on the filter vs. no filter question.

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Original contents copyright 2012 by Michael C. Johnston and/or the bylined author. All Rights Reserved.

Comments

[Will Whitaker (old film user)]

"...old film days..."??

That would be like Charlie Chaplin, right?
But an interesting article; thanks!

[Jack]

Regarding using filters for protection.
I once advised a friend who was buying a camera to use in photographing his children, to buy a filter to protect the front of the lens. He bought the camera, and put on the filter. His first photograph with that camera turned out to be of his young son flinging a small toy right at the camera. The toy cracked the filter but not the lens. The father's only comment was that I should have advised him to buy a second filter when he bought the camera. While I rely on lens hoods as protection now, a lens hood would not have stopped that small thrown toy, the child was that accurate.

Note, a cracked filter causes a lot of haze.

[Ken White]

I always hated seeing flare in my images even though it seems to add something to the images made by other people. Sometimes when the sun is fully in the frame you get some interesting effects.
Sun fully in the frame with lots of flare on a foggy morning in the West Texas oil patch.
http://www.pbase.com/kwhite/image/122111451

[Daniel R. Fealko]

Excellent article! Unfortunately, at least on my computer, the "Animation showing scanned Tri-X negatives from the 50mm f/1.4 lens" is frozen on "Lens Hood." The prior animation works fine. Again, an excellent article.

[Mike Johnston]

Daniel,
Unfortunately I don't know enough about it to help you. It tests fine on Safari and Firefox for me.

Sorry...

Mike

[ILTim]

By using a filter for protection, you are simply altering the design of the lens such that the front element is field replaceable, industry standardized, and low cost.

I think that particular assemblage of words takes a lot of wind out of the anti-arguments.

[Peter Dove]

M'sieur, does your lens flare?

No, my lens does not flare.

Mon Dieu! I thought you said your lens does not flare!

M'sieur, zat is not my lens.

[MarkB]

Yes, yes, "use a hood all the time," even if makes your otherwise inconspicuous lens look like a howitzer!

Filters are for filtering (removing some part of) light for a desirable effect, not as a resale shield. I'll only give quarter to those who shoot in sandstorms and on helipads, though.

[Jeff]

Uncharacteristically, this post contains some glaring errors.

[Sarge]

W O W !

[Daniel R. Fealko]

Mike,

Thanks. Not sure what happened as it's working now in Chrome too, but was definitely stuck earlier. Computers can be rather annoying at times.

Dan

[Michael Farrell]

Put it down to my perverse need to get weewee'd up about things over which I have no control; lately it's been DSLR users walking in the sunshine with UV filters on their lenses and hoods fitted on backwards that gets my gorge rising.

Photography gods, I silently scream, please take pity on these poor souls. They've already spent good money on nice equipment and suffered the indignity of being upsold a piece of glass they don't need. Don't condemn them to a lifetime of filter flare and flat contrast; help them find an online article that points out the error of their ways.

[Dave]

Very informative, thanks. My primary lens has a UV filter that is basically glued on. I am really rough on my equipment and the UV filter gives me piece of mind. However, I absulutely hate veiling flare. Maybe it's time to ditch the protection. I'm going to read Mike's take now and then make up my mind. It's funny how much anxiety that little piece of glass causes.

[Paul Glover]

As the owner of a late-1950s era Yashica TLR, I'm intimately familiar with veiling glare. A lens hood helps, but what really makes a difference on those old cameras is using matte black flocking in the interior to cut down on the amount of light bouncing around between lens and film. I haven't done that yet but I've seen examples of the difference it makes. I've seen improvements just by applying black permanent marker to some silver-colored areas which would be exposed to incoming light.

[William Schneider]

Daniel,
Try copying the problem GIF file to your computer's desktop, then drag it into the browser window. That will display it by itself.
Perhaps a memory issue on your machine permits only one animated GIF file to display at once. The second file WAS fairly big.
Animated GIF files are an ancient technology (well, in computer years at least), and normally shouldn't require anything more than a browser to run.

Ken,
The photo linked shows atmospheric haze more than flare. That's part of the scene itself and not caused primarily by the camera optical system. Having taken advantage of fog and haze myself, I agree that these conditions can make a picture more appealing.

Bill Schneider

[Cliff]

Good article.

But also, when using full frame (film) lenses on smaller (APS) sized sensors it’s a good idea to use a deeper hood. My old 35mm film lens gives a 50mm equivalent angle of view on APS-C. So, I use a hood sized for a film 50mm.

And/or, just shoot some test frames to find the deepest hood that does not darken the corners of the frame. Don’t forget to test with filters added, too.

[kirk tuck]

I own polarizing filters for times when the light needs to be polarized but I would never, ever put a "protection" filter on the front of my camera. That's as dumb as wearing your bicycle helmut in your house or office just in case something out of the ordinary should happen.

You probably paid good money for your lens so it would be sharp and contrasty. Adding two more air/glass interfaces messes up the optical formula those poor lens designers worked so hard on....

Can you see people with really nice watches putting protection glass over the crystals, just in case? Grow a pair and shoot with your lenses the way God and the optical designers intended.

[Mathew Hargreaves]

This column only addresses the UV filter possibilities to control different flares. In your previous column I did bring up the idea of using a polarizing filter over the lens to reduce the unwanted lightwaves. I seems to me the best test would be to shoot the same scene without a UV filter, with a UV filter, and with a rotating polarize at different settings.

[David Dyer-Bennet]

The illustrations for the two lenses show the chart at such different magnifications, cropped fairly tight in one case and showing the whole scene in the other, that's VERY hard to make any kind of comparison between them. This is such a blatant violation of the rule of varying one thing when trying to illustrate something that it almost has to be intentional, but I'm missing the point, and find that it makes the whole article nearly useless.

[Colin Work]

I'm completely filter free with one exception - harsh environments. I believe that with Canon lenses anyway full weather-proofing requires use of a filter. Besides, I would rather hastily wipe salt away salt spray with a T shirt from a filter than the front element!

One exception I do make is the use of a polarizer for creative effects - its the only filter effect I can't replicate (or possibly improve on) in Photoshop.

As to lens hoods - absolute must for me, both for glare and protection - the scratches and nicks evident on my hoods very clearly illustrates their value!

I'm always surprised by the number of people I see with the hood in the stored position - I wonder if some people buy the lens like this and don't realise it's reversible. If you didn't know much about photography, perhaps it's not obvious.

Cheers,

Colin

[ctein]

Dear DDB,

I think maybe you're looking for the wrong information? This isn't a comparison between the two lenses directly, it's a comparison between how their flare changes when they have filters or lens hoods attached -- both lenses show a lot more flare when the filter is attached, but the low-flare lens is little-affected by attaching a lens hood. That comes across clearly in the animated GIF regardless of image size.

pax / Ctein

[Mike Johnston]

David,
I think each set was meant to be self-contained, but Bill can speak up if he wants to....

Mike

[David A. Goldfarb]

Good demo. I make this argument all the time. Most flare comes from the subject itself. I always use a lens hood and only use protective filters when there is an obvious hazard.

[Mike Johnston]

It's also important to realize that a) all optical systems suffer from flare to at least a small degree. Nature of the beast; b) most pictures don't suffer from it enough to notice (or to worry about); c) a lens hood makes a difference some of the time but not always. So if flare is not a problem in 80% of your shots, a lens hood will make it so it's not a problem in 85% or 90% of your shots. It's just going to improve your odds--it's not a panacea.

Also, I should have mentioned in my "never use a filter" article that for 20 years I always used a filter, because I liked the look of Plus-X and Tri-X with a yellow filter on the lens. The change in spectral response was worth the very slight downside in optical quality.

Mike

[William Schneider]

David,

I hadn't intended to compare the two lenses against each other, but I can see how the different magnifications are distracting.

I'll attach the cropped 50mm 1.4 lens example to this comment.

Note that because the lens focal length between the lenses is different, the 50mm example will be a little larger using the same crop dimensions.

Also, I did not attempt to retouch the scratch visible in one frame in the animation.

[the other James]

It's interesting that suddenly everyone's talking about flare. The new Canon 40mm f2.8 is very exciting me because the simple, low element/group design, combined with modern coatings, means it's a very flare resistant design. As someone who shoots at night, with lights in scene, that matters to me. A lot. If only I had a buck to my name...

[David Bostedo]

"By using a filter for protection, you are simply altering the design of the lens such that the front element is field replaceable, industry standardized, and low cost.

I think that particular assemblage of words takes a lot of wind out of the anti-arguments."

No, it doesn't, because you didn't anywhere in there address the fact that you are making the lens performance worse; Especially if you think it's low-cost.

[Ed]

A filter on the front does not alter the optical formula. Middle or back, yes, but not the front.

Ed

[Stan B.]

Many years ago a big time pro stated that it was ridiculous to put a ten dollar piece of glass (going price for a filter back when) in front of a premium piece of glass costing hundreds. Naturally, I followed the pro's advice, took the UV filter off and a couple of weeks later had a nice gash on my front element to show for it. Ever since I've had a multi-coated filter on front of my lens- along with the lens hood.

[Kenneth Tanaka]

Count me among the filter-less crowd in much the same spirit as Colin's remarks.

The old UV Haze filters made sense in the color film era where (a) excessive ultraviolet light could fog a film, and (b) there was little that you could do about it after the shutter closed. Those days are past.

If I frequently photographed in blowing sand or nasty environments I'd consider using a protective filter during daytime. But filters, even coated filters, bring their own issues especially at night. If you want to shoot plenty of UFOs just screw a filter on any lens and shoot near point sources at night.

Today's lens coatings are 10x tougher than those of 20 years ago; they can take a bit of a beating.

The eternal quest for perfection has produced some of history's most dreadfully dull imagery.

[ctein]

Dear Ed,

Actually, yes, it does. The effect may be ignorable, but it does alter the optical design. This is not the place for long technical arguments, so if you want to discuss this, email me: [email protected]

pax / Ctein

[David H.]

I don't use filters to protect my lenses and have never had a lens damaged from not using one. (I suppose I will now, since I wrote that.)

If I were to worry about a freak accident damaging a vital, irreplaceable lens, I'd wear safety googles everywhere.

[Andrew Burday]

If anybody is still following this thread, PDN Photo of the Day happens to have several images up by a photographer who is deliberately, massively using flare in her images:

http://pdnphotooftheday.com/2012/07/15714

I don't particularly like these images, but you want flare... she's got flare for you.