Lens flare tutorial

About 15 years ago I took a photo in Canyonlands National Park which would have been one of my favourite landscape photos I had ever taken. I remember getting excited about it at the time, but this was when I was still shooting on medium format film, so I had to wait a few days to see the results. Once back at the processing lab in London, I remember the anticipation of seeing this particular shot, wondering if it had come out as good as I had remembered it. I also remember the immense disappointment when I put the film on the light box and saw the huge amounts of lens flare which had ruined the shot.

One of the major advantages in digital photography is being able to see the image immediately after capture. Had I shot this digitally at the time, I would have seen the flare problem, and would have been able to deal with it. With this in mind, I returned to the same spot recently with a few customers who were attending the Worldwide Explorers photo holiday to Utah which I was leading. Although I have been to the same location several times since my first attempt to capture it on film, the conditions have never been right to attempt to repeat the shot. This last visit however looked promising, so once all my customers were set up and happy with their own compositions, I embarked on settling a 15 year old frustration with this particular landscape.

Lens Flare reduction

Some lenses deal with flare much better than others, and in my experience, this has little to do with the price (or quality) of the lens itself. I have some very expensive high end lenses which do not cope at all well with flare, yet I have some quite cheap lenses which seem to take flare in their stride. The lens I was using here (Canon 16-35 f/4 L IS) is one of the best lenses I own for coping with flare. It is my go-to lens when shooting into the sun, but even this was having problems with the bright sun and deep shadow areas. After unsuccessfully trying a few of the usual tricks which we will discuss in a moment, I had to apply a technique known as The Last Resort in order to eliminate all the flare. The Last Resort is something we will come onto later, if you are brave enough to read about it.

One of the most common questions I am asked about during the workshops and photo holidays I run is how to eliminate lens flare. Depending on the situation, this can either be very easy or quite difficult to deal with.

There are two types of flare which we are likely to encounter as photographers. The most noticeable one is specular flare, which is caused by a bright light source (usually the sun, but it can be street lights in low light or astro photography) creating coloured blobs of highlight over other areas of the image.

Lens flare

The other type of flare is ghosting which is less obvious but just as damaging. This is where you have excess light bouncing around inside the lens, some of which ends up finding its way onto the sensor, resulting in contaminated shadows which reduce contrast and generally lessen the clarity and crispness of an image.

Lens flare problems

Both types have the potential to ruin an image, so it is essential to know how to deal with them.

I should start out by saying that specular flare is not always a negative thing, and some photographers actually look to enhance it or (if you are truly insane) even create it at the post production stage. My personal view is that an image is usually better without specular flare, but if you want to include it for atmospheric purposes, the golden rule is that you must be able to see the light source which is causing the flare. For example, if the sun is outside of your frame but is shining on the front element of the lens, this may cause specular flare which is going to be undesirable as we cannot see its source. However, if the sun is part of our scene (as in the first example above), then it can be argued that in some situations, specular flare can add something to an image. There are no rights or wrongs here, and this is for you to decide at the moment of capture. If you consider that specular flare is desirable then you really don’t need to do much, although you can enhance it by experimenting with different apertures. You can also experiment with moving the position of the flare to different areas of the frame by adjusting the angle of the lens to the light source, or by adjusting the focal length until the desired effect is achieved. If however you want to eliminate flare from your shot, here are a few things to can try.

Lens Hood

Let’s assume the light source is not within our frame. In this situation, the problem is easy to deal with. All we need to do is to reduce the amount of excess light from entering the lens. This is what lens hoods are for, yet despite this, many photographers fail to use them. I cannot stress how useful the use of a lens hood is. To have one and not use it should be a criminal offence under the Photographer’s Intelligence Act of 1985. Lens hoods take on two vital roles. The first is to reduce peripheral light from entering the lens. This will assist in reducing both types of lens flare. The second is to protect the front element of the lens from impact in the event that you drop your camera or knock it against a rock or a tree. There are no optical downsides whatsoever in using a lens hood. The only practical downside is that it can prevent the use of filters being applied. However, when not using a filter, always use a lens hood as it will only ever improve the quality of your images.

Shade the lens

Lens hoods are only capable of reducing some of the peripheral light from entering a lens. Even with a lens hood attached, you can still help reduce or eliminate lens flare by additionally placing a shadow over the front element with either your hand or a hat. This is most effective way to eliminate specular lens flare, and to reduce ghosting. If using a tripod, it is super easy to look at the front of the lens and cast a shadow over it as you take the shot. If you are handholding the camera then this can take a little more practice but it is certainly not difficult to do.

Lens hoods on wide angle lenses are of less use than those on longer focal length lenses. You will need to do a lot more shading on wider lenses than on longer ones. Ironically it is more difficult to shade a wide angle lens without your hand creeping into shot, but this is why we love photography - because it is a challenge.

Reducing lens flare

Use of filters

Filters can be a great asset to the landscape photographer, but only use them when they are needed. Too many people use filters unnecessarily, and despite what you might think, there isn’t a piece of glass that exists in the world which will improve the quality of your image. Every time you place another layer of glass in front of your lens, you are degrading the image, so only ever use filters when the advantage they will give you is greater than the loss you will experience by using them. This is also true with lens flare. The more surfaces of glass the light has to reflect off, the more chance you will get flare problems. This means that by using a filter (especially if you need to remove the lens hood to fit it), you are increasing the effect or chances of getting flare.

The problem here is that flare is only usually an issue when you are shooting into the light. This is also the only time when you are likely to need to use a neutral density graduated filter in order to control the dynamic range of the scene (bright sky with a dark backlit foreground). In this situation, it is essential that you place a shadow over the lens as you take the shot.

Filters are available in many standards. Always use the best possible quality filters, as saving money in this area is a false economy. An image is only as good as the glass it passes through, and if you use cheap filters on a decent lens, you negate the quality of the lens. Try to get glass filters over resin ones, and get ones which are coated to help reduce flare, dirt and water. I use Kase filters which tick all the above boxes. If you have one of those well known filter holders with the polariser at the front, then you will get loads more ghosting than if you use a more practical design where the polariser is light sealed and mounted at the rear. If you can see the back of your polariser once it is fitted to the camera, it means light can also see it, and it will reflect off the back surface, resulting in a loss of contrast. If you have one of those protective screw in filters (UV or Skylight) then removing this will assist in reducing lens flare. I only ever use such filters in extremely dusty environments or when in a situation where sea spray is likely to contaminate the front element of the lens.

Lens ghosting
This image shows both specular flare and ghosting. This is what happens when you fail to use a lens hood and reduce the amount of light entering the lens

Lens shielding
This image has my hand shielding the lens from excess peripheral light. Compared to the previous image it displays far more contrast and no flare

Keep surfaces clean

Dust, water and finger smudges will all increase the chances of flare being noticeable, so ensure the front element of the lens is clean, especially when shooting into the light. If you need to use any filters, ensure these are also clean.

It should seem obvious, but in order to properly clean the glass of lenses and filters, you need to have a decent lens cloth which is absorbent. It is amazing to see photographers wiping their lenses with face flannels, tissues, or even some lens cloths which are not absorbent and simply smudge any water or grease around the glass, often making it worse than it was before they stated cleaning.

Lens variables

Prime (fixed focal length) lenses only have one variable (aperture), whereas zoom lenses have two variables (aperture and focal length). Lens variables will have an impact on flare, but there are no set rules here. If you find that you are getting flare, experiment with using different apertures and focal lengths to see if you can reduce the effect.

The Last Resort

We’ve already spoken about shielding the lens with your hand or the brim of a hat, but what happens if the light source is within your frame? You can’t possibly shield this with your hand, otherwise you will see your hand in the shot. Let’s say the light source is the sun, and the sun is within your frame and is causing excessive and unwanted flaring (as in the title example in this article). If you have tried all of the above without success, then you need to delve deep and adopt a special technique known as The Last Resort. This isn’t pretty or for the faint hearted, so stop reading now if you are of a nervous disposition or just don’t have the metal for such a drastic measure.

You need to use a tripod for this technique, so set up the composition and other parameters as normal (exposure, focus, etc). You must be in Manual Mode, as Aperture Priority or any other semi auto mode will mess this up for you. Once you are ready to take the shot, look through the viewfinder (or use live view) and place a finger over the sun. Attack it from the top so that your finger doesn’t interfere with any other objects in the foreground. You will see that once your finger covers the sun, all the flare will disappear. Now take a shot. You now have a shot without flare, but the problem is that there is a big sausage like object in the sky! Now remove your finger and take another shot. This should give you a clean sky but loads of flare over the shadow areas. All you now need to do is to merge the two together - using the foreground of the one with your finger in front of the sun, and the sky from the version without your finger in it. Voila - a clean shot with no finger and no flare. Now there’s a great title for my debut album - No Finger, No Flare!

Lens flare merge3
This shot has no flare on it but a big finger in the sky

Lens flare merge
This shot has several unwanted specular flares in a line from the sun to the lower right corner. Merging the best parts of the above 2 images gives the result seen near the beginning of the article

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