If you're unfamiliar with what lens flare is then it's the hazy washed out areas in an image that appear far brighter than they should do. You usually can't see flare with your own eyes but when you take a shot, there it is and often it's an undesired effect that can ruin several aspects of your photo including contrast.
Not all flare is bad. There are plenty of times where flare in portraits with the light behind the subject can create this misty dreamlike effect. But what about those times when don't want it, what can we do to avoid it?
Sometimes we want to use flare to add interest or drama to a shot but a lot of the times in the studio it is one thing we want to avoid as much as possible. Some backlit portraits can benefit from the dreamy effect that flare offers but still life and beauty shooters will go weak at the knees at the mere mention of flare. They spend all day crafting pin sharp focus along with crisp highlights and shadows so any flare present in a shot would ruin all of that hard work due to flares inherent ability to reduce overall contrast.
So whether you want to add flare or not, it's a really good idea to know what can cause flare in a studio environment. From a technical standpoint, flare is light that has bounced around inside your lens and camera in an undesired and unexpected way. This results in this scattered mist-like light effect we call flare. For this to happen light usually has to be pointed directly into the lens, that being said, there are times where the curvature of the front element of the lens can catch the light in such a way from the side that it will also cause flare. This is rare though as most lenses now have a slightly recessed front end that keeps the lens curve hidden and the addition of a lens hood will hide it even further.
In the studio we have control to move our lights so we can avoid pointing them into the lens as much as possible but there are still occasions where this is hard to avoid, like when using hair lights or even side lights. These lights are ordinarily pointed back towards the camera and so run the risk of creating flare unless we take alternative action to minimise the effect.
Below are five things you can do to limit the amount of flare into your lens.
Prime Lens Vs. Zoom Lens
A prime lens is any lens that has one single focal length, a 50mm lens for example. A zoom lens is any lens that allows you to adjust the focal length, for example a 24-70mm.
Most of the time a prime lens will have far fewer moving parts and a lot less glass housed within the lens itself. This results in a lot less glass for the light to be bounced around on and through so ultimately it results in a far crisper image. Conversely zoom lenses have a lot of extra optics inside them so the chance of flare being created is far higher.
What you're looking for is areas that should really be in shadow but are a milky grey colour instead, that is the result of flare. In the above shots you should see that the prime lens simply has more overall image contrast.
Again with this single hard light pointed straight into camera we see that although we're still getting flare on the prime, it's far less apparent than what we have with the zoom.
Long Lenses Vs. Wide Lenses
A lot of the time a longer lens will not only place you further away from the subject, thereby reducing the chance of the light entering the lens, but wider angle lenses by design will have to have a more curved front element. It's this curved front glass element that is far more likely to catch the light. As a general guide anything that is wider than 50mm is classed as a wide angle lens so for the best chance of avoiding flare with lights pointed towards camera, try to use a focal length of at least 85mm.
I have clearly used two extreme focal lengths here to illustrate my point but it should be clear to see just how much flare is present in the wider 38mm shot compared to the 105mm.
The very wide angle 38mm lens here is a great example of what happens when a wide angle lens has its curved front element exposed. That exposed front element catches the light at every available opportunity and it results in this extreme multi faceted flare effect. Great if you're JJ Abrams, but not so much for regular portraits.
Good Glass Vs. Bad Glass
Contrary to popular belief this is actually less of a problem than you might think. For those who aren't sure what I'm referring to, I'm essentially talking about cheap lenses Vs. expensive lenses. Glass quality has been exceptional for many, many years so the cheaper lenses aren't always as bad as the press and the marketing might have led you to believe. Don't get me wrong, there are of course other benefits that come with better quality lenses but I struggled to find a lens to prove this point. I ended up using a lens from the 1960's here to actually show two images with any real visual difference in them when it comes to flare. Bottom line; if you're buying a modern lens and you're not too bothered about very small amounts of practically indiscernible flare, you should be fine.
Although poor lens quality is often blamed for flare in lenses, you'll be pleased to know that this is actually the least of your worries. The image on the right above was taken with an old manual focus lens from the 1960's and it's still only displaying minor amounts of flare compared to the modern prime lens on the left.
Again, only a small amount of flare is present in the 'vintage' lens compared to the modern day equivalent. Plus the vintage lens is a zoom compared to a modern day prime on the left.
Narrow Vs. Wide Aperture
Just to clarify from the start; narrow apertures are the f11s and f16s and wide apertures are the f2.8s and f1.8s. They are referred to as narrow and wide because in the lens itself, the aperture opening is a large hole letting in a lot of light and the narrow aperture is a tiny hole only letting in a small amount of light. It obviously stands to reason then that the aperture that allows light to pass through a bigger hole will bounce around far more and ultimately produce more flare. If you're really struggling with flare closing your aperture down to something like f11 will likely eliminate a lot of it.
You should be able to see that the f1.4 shot on the right has more detail in the shadow areas due to haze-like flare. Some may argue this is a good thing but unfortunately it isn't because that detail is lacking in any contrast due to the haze. Look at the light creeping around the models right arm in both shots to see how that lack of contrast is undesirable. *Side Note: I have no idea why even after double checking the Kelvin values, the image on the right is considerably warmer than the image on the left.
The f11 shot here is very crisp and with a lot of contrast, conversely the f1.4 shot has that extreme flare entering the image. The only difference between those two images is the f number illustrating just how much of an effect it can have.
Lens Filter Vs. No Lens Filter
I wont lie, I was looking forward to actually testing this theory but I was not prepared for the results. I am renowned for always preaching to people about removing their U.V. or Skylight filters from their lenses on my workshops. Yes I know they are there to 'protect' your lens but in reality they aren't going to protect your lens if you drop it. The 'up-sell' add-on of selling a lens filter to you at the time of you buying a lens was created by camera salesmen years ago and the myth has perpetuated (yes I was sold one by Jessops staff many years ago too ;) ). To this day there is a very small margin to be made on selling hardware like cameras and lenses so camera stores understandably do everything in their power to sell you add-ons like the lens filters and camera bags etc. It simply seems madness to put a £20 filter on a £2000 lens and if I still haven't convinced you then the images below surely will.
All lenses are made up of optics and those optics are there to focus and align the image correctly onto your camera chip. Optics are made of glass and for glass to do anything to light it has to be curved in some way as flat glass does absolutely nothing. Basically speaking there are zero flat pieces of glass in your lens....apart from the lens filter you slap on the front. It's this single piece of flat glass in the system that creates the problems especially when we are talking about flare.
Please take a good hard look at the images below and REMOVE your U.V. Skylight filter immediately.
I was looking forward to testing my flare theory with and without lens filters attached but I simply wasn't prepared for the results. I swear to you that both of these images are raw and that I am only using a single U.V. filter on that lens. The difference in my mind is incredible and if you're somebody who still has a lens filter attached, please consider removing it or at the very least doing a similar test yourself to see what I mean.
These shots need little explanation but I think it's a really good example of a mistake we've all made and gotten frustrated with when it simply wasn't our fault to begin with. I think it's incredible that camera salesmen sell us a £2000 lens, then told us to put this crappy £20 filter on the front to 'protect' it. I would not have been impressed with my lens purchase if this was the result I was shown.
So all I need is a really expensive 300mm prime lens and shoot at f64 with no lens filter and I'm all set?
So there you have it, the 5 things you need to be mindful of if you're looking to reducing flare in your studio lighting shots. Pretty simple right? All you have to do is shoot on a really expensive, 300mm prime lens at f64 with no lens filter right? Well sure you could do all that but no that's not necessary. Most of the times there will be things that you don't want to change about your shot, like if you want to shoot at f2.8 but your shot has flare in it. Rather than changing the aperture you could simply step back and zoom in a little and that would likely solve the problem. Although all of these 5 things play a part in creating flare, more often than not it's only one of them that's causing it so being aware of them all allows you to compensate accordingly.
So if I do all of these 5 things I'll never see lens flare ever again right?
Unfortunately, although I've outlined the 5 core reasons you might be getting lens flare and how to avoid them, there is one more fundamental reason that is by far and away the biggest contributor to flare in the lens, and that's exposure.
Poor exposure is by far and away the easiest way to get flare to appear in your shot. Most of the images I've seen with flare have had a light pointed back towards the camera that is too powerful. This overpowered back-light simply isn't needed in most cases and if you have a correctly exposed back light you can shoot into that light all day with whatever modern lens you want and you'll likely be fine. Experiment with what you think looks best but always turn that back light down lower than you think and turn it up if needed. It's always far easier to deal with slightly underexposed highlights than overexposed highlights.
Even an overexposed back light with as little as 1/2 stop of too much light can start to create flare. See how there is a milky haze in the shadow areas here? That is unwanted flare.
Regardless of what lens, focal length or aperture you use, if your backlight is overexposed it's going to create flare. Never be afraid to turn that backlight lower than you might think.
Closing Thoughts
So those are the five core reasons for flare appearing in the lens when shooting in the studio. But like I pointed out at the end, all of it is completely pointless unless you are correctly exposing that back light.
As always, thanks for taking the time to read this, I hope you've found it in some way useful :) If you have any questions then don't hesitate to ask away in the comments down below. If you're new here then feel free join our very active community of like minded lighting-nerds on my Facebook page, I'm always discussing lighting ideas and offering feedback on community images. If you'd like to stay up to date on more photography related tips and techniques then sign up to my mailing list where I'll send you a monthly roundup of all my articles (plus signing up gets you a free 10 page studio lighting pdf too :) ). Thanks again and I'll see you all in the next one.
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