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Purple flare test: iPhone 5 vs. Samsung Galaxy S III vs. HTC One S

Given its pedigree, it's no surprise that the public expected the iPhone 5 to be a flawless device. So when a problem rears its ugly head, it's equally not surprising that the Internet starts to act a bit like Chicken Little, running around in a panic proclaiming that the sky is falling. The latest black mark against Apple's flagship smartphone is actually purple in colour, and comes in the form of lens flare.

As we reported at the end of last week, the iPhone 5 has a tendency to capture frame-filling purple lens flares when a bright object, like the sun, is framed in the corner of a shot. Take a look at the test image we snapped at the top of this article, which shows the iPhone 4S compared to the new iPhone.

This development comes as no surprise to old-school photographers who remember shooting with uncoated lenses. But digital sensors are much more prone to capturing the bright purple hue associated with flares and fringing than film. For a generation raised on cameras equipped with multi-coated autofocus lenses, this is a new animal. Modern photographers complain about purple fringing when shooting dark objects against a black sky, but that goes away with a few clicks in Lightroom – however, that's not the case with large flares.

At any rate, we thought it would be a useful exercise to take a more in-depth look at the purple flare problem, and compare the iPhone 5 not just to the iPhone 4S, but also the iPhone 4, and rival Android handsets the Samsung Galaxy S III, and HTC One S.

We tested by trying to induce flare in our studio using a 500 Watt tungsten light with a daylight gel filter. The results follow, and first up, we have the iPhone 5. The shot on the left is framed so that the light source occupies the top corner of the frame, introducing a large, purple lens flare into the photo. The image on the right is taken from the same position, but with the light source moved so it’s just out of frame – and as you can see, contrast suffers, and the image is draped in a bit of purple haze:

Next up, below we have the iPhone 4S, which as you can see from the image on the left still shows some lens flare, but the purple colour isn’t present. And on the right hand photo, with the light source out of frame, the contrast suffers a bit, but again there’s no hint of purple haze:

Moving onto the Samsung Galaxy S III, the left side picture below still shows some flare when the bright light is placed in the corner of the frame, but it's not as pronounced as with the iPhone 5. With the light source just off to the side, the right image shows a bit of light in the corner of the frame. There's no purple cast, although contrast is reduced due to the side lighting, much as it is with the iPhone 4S:

The HTC One S has a wide-angle 28mm lens, so its field of view is a bit wider than the other phone cameras tested. As with the other phones, flare is present when framing a bright light in the corner, in the left hand side image below. On the right hand image, due to the aforementioned wide lens of the HTC One S, there's still a bit of light in the corner, but as you can see from this shot, there's no purple – just a white cast that reduces image contrast:

Finally, we have the iPhone 4, the elder statesman in this shootout. Its lens is especially prone to flare when a bright light source is placed in the corner of the frame, as you can see from the left hand side image below. The right side image, having moved the light source out of frame, gives you a shot with a bit of a purple cast, although the iPhone 4’s contrast doesn't suffer as much as it does with the iPhone 5:

So, in summary, of the phones tested, only two were able to really suppress flare: The iPhone 4S and Samsung Galaxy S III. Putting the iPhone 4 aside, which has a camera that is now pretty dated (and, despite a cleaning before the test, is probably not better off for having lived in my trouser pocket for the past two years), the latest and greatest iPhone 5 was clearly the worst offender of the bunch.

But what causes this? As much as I like to take photos, speaking intelligently about the intricacies of lens design and performance is a bit beyond me. But the most likely cause is a combination of the lens design and, more importantly, the coatings used in its construction.

Modern coatings are designed to minimise reflections and have all but eliminated severe flare in SLR lenses. Nikon says that its latest coatings will let you shoot into the sun without a significant loss of contrast. On paper the iPhone 4S and the iPhone 5 have a lens that's identical, save for one crucial factor – the new scratch-resistant sapphire covering that protects it from scuffs and scratches. Whether Apple used a different coating on this cover, or if the coating is unchanged and it's simply not behaving well with the sapphire material is anyone's guess.

Some sites, including Petapixel, and various Internet commenters have postulated that Apple's removal of the "IR/Cut" filter is introducing the flare. Leica infamously put a weak IR filter on its first digital rangefinder, the M8, but that didn't increase flare. Instead, it made certain synthetic black fabrics appear to have a magenta cast and gave lush, green vegetation a bit of a yellow tint when shooting colour images, requiring the use of special 486 UV/Ir filters to give photos a proper look. This isn't the case with the iPhone 5, as the iPhone 4S uses the same Hybrid IR Filter, but isn't nearly as prone to flares as its successor.

Should this stop you from buying an iPhone 5? Obviously, that depends on how important the flare issue is to you. Shooting into the sun isn't the best photographic technique, but it sometimes can't be avoided – unless you're shooting a stationary subject and have a few hours to wait around for the rotation of the Earth to move that pesky sun out of your frame. If you're grabbing a family snapshot, the best thing you can do is to put the sun at your back – it puts your subject in a more pleasing light and will make flare a nonissue.

Flare is but one aspect of the camera's performance – shots from the iPhone 5 are noticeably sharper than those from the Galaxy S III, especially when shooting in macro mode, even though that phone's camera is less prone to flare than the iPhone 5. If you've currently got a 4S, you have the same camera, minus the flare issue. If you've got an HTC One S in your pocket, be aware that flare can happen, but you do have to make an effort to induce it – and that lens opens up to a wide f/2 aperture, which gathers about 50 per cent more light than the iPhone 4S and 5.