When it comes to basic image quality mobiles today can compete with many consumer dSLRs. Features such as RAW management and HDR, along with countless apps that extend mobile camera functionality, have led industry big shots such as Vincent Laforet to make bold predictions about a world in which only the most elite photographers use anything other than a mobile.
Still, one key limitation continues to afflict the mobile cameras: the lens. Mobiles have very small lenses compared to dSLR and mirrorless cameras. The size of a camera lens is important in several ways. Understanding a bit about lenses can help you solve some of mobile photo’s thorniest problems. Here are a few tips and examples of accessories that will help you get more out of your mobile.
Let there be light
The lens controls how much light strikes the sensor, which in turn control exposure and the ability to freeze motion. Mobile lenses are much smaller than the lenses in bigger cameras. An average diameter for a mobile camera lens is 4.4mm. An average diameter for a dSLR is 22mm.
It takes longer for the same amount of light to pass through an 4.4mm opening than to pass through a 22mm opening. The result is longer exposure times with mobiles that often lead to blurry images. Image sensors and stabilization technology is getting better and better but mobiles continue to struggle in low light or with fast moving objects.
One way to get better results with your mobile is to ensure as much light as possible when you shoot. It takes A LOT more light to get exposure with a mobile than to see with your eyes. Work during the day. Move closer to strong light sources. Open the curtains. Stabilize your camera to avoid blurriness caused by hand movement.
To zoom or not to zoom
There are two kinds of zoom: optical zoom and digital zoom, one good and one bad. Optical zoom, good zoom, is true zoom. Optical zoom lenses in dSLRs and point-and-shoots have several pieces of glass, called elements, in the lens barrel. When you push the zoom button or turn the lens barrel the elements move closer or farther from one another, changing the magnification without loss of image quality.
Mobile cameras have only one lens element and only support digital zoom. When you zoom with a mobile, done on most mobiles by “pinching” the screen with two fingers, the camera is simply cropping the visible image by enlarging the pixels. Image quality -- and stability -- deteriorate very quickly. Bad zoom.
I never zoom with my mobile. Better to physically move closer to the subject so image quality remains high. As an alternative, you can crop the image after you shoot in your native camera app or with a post-production app.
Extend The Lens
As explained above the lens in your mobile does not really zoom. The lens is fixed at a single focal length in the range between wide angle and telephoto. Different mobile manufacturers make their cameras with different fixed focal lengths. Typically the front-facing camera is wider angle than the front camera to make taking selfies easier. But, the front-facing camera is not as good in image quality.
Most mobile manufactures make the focal length of the back-facing lens equivalent to something in the range of 28mm to 35mm in a dSLR. The actual number is relative to sensor dimensions, which change from mobile to mobile. In the product specs the number is often given as the more standardized dSLR equivalent. For example, the Samsung Galaxy S5 has in reality a 2.2mm lens but it is described as equivalent to a 31mm lens on an dSLR.
There are several different types of lenses and accessories you can buy to change the focal length of your lens or give it optical zoom. Olloclip makes a variety of high quality snap-on lenses for mobile phones. That can extend the focal length of your mobile from super wide (16mm) to telephoto (120mm). A limitation of these lenses is that they are often manufactured for specific phones and specific cases. Every time you upgrade your phone or buy a new case you need a news lens.
Another approach to improving mobile lens quality is the self-contained attachable lens. For example, the Sony Cybershot DSC-QX30 mounts on your phone and uses Bluetooth technology to connect. The Sony features a high quality lens with a larger aperture and 30X optical zoom. You use the Sony app and your mobile touch-screen to take the photos, making your phone little more than a storage device for the images. An interesting feature of this style of lens is that the lens does not have to be physically attached to the camera. The Bluetooth range is about 5 meters.
An emerging mobile photo and video advance is the DxO One. This device allows your phone to produce extremely high quality photo and video. It features a fixed lens (32mm) with a very large aperture that is capable cinematic image quality. The DxO One plugs into the power port on your mobile. Like the Sony it uses the phone as a camera control screen and as a storage device.
The future of mobile as a production tool for photo and video is not in doubt. Accessories that work to overcome lens limitation and extend functionality are surely part of the equation.