Is there much practical difference in image quality between a picture shot with an 8-megapixel camera and one taken with a 5-megapixel camera? The megapixel count reflects the size of the camera’s sensor--a small device inside the phone that converts an optical image into an electronic signal. The higher the pixel count, the higher the resolution of your photos. But you’ll probably view most of your photos on your phone’s display or on a PC, where the two resolutions are typically indistinguishable. If you plan on printing your photos, however, a higher megapixel count will make a difference.
As is true with point-and-shoot and digital SLR cameras, more megapixels doesn't automatically mean better image quality. Other factors that affect image quality include the quality of the camera lens (the Nokia N-Series phones, for instance, ship with lenses made by Carl Zeiss, a company that also makes lenses for high-end digital SLRs), the accuracy of the camera’s autofocus features, and the camera's shutter speed (this is especially important if you’re shooting a fast-moving subject). Shooting modes for various light environments (low-light indoors, evening, nighttime, etc.) can also help improve image quality.
4G and HSPA+ Service
The major wireless carriers are currently upgrading their 3G networks to 3.5G (HSPA+) or 4G (LTE or WiMax). Whether a specific smartphone supports these new network technologies (and their faster speeds) should be stated in the device's specifications.
Sprint and Verizon are in the process of rolling out new 4G networks, capable of delivering speeds that may be up to 10 times as fast as those possible on the carrier's older 3G networks. Verizon says that its LTE network offers download speeds of between 5 and 12 megabits per second (mbps). Sprint says that its WiMax network has average download speeds of between 3 and 6 mbps.
AT&T and T-Mobile are upgrading their 3G GSM networks to a 3.5G technology called HSPA+ (Evolved High-Speed Packet Access), which can match the speeds of current 4G networks. T-Mobile even refers to its HSPA+ service as “4G.” AT&T makes no such claim, but it says that it has already converted 80 percent of its network to the new HSPA+ technology and plans to begin rolling out its 4G LTE network in 2011.
In our tests, both T-Mobile’s and AT&T’s HSPA+ networks delivered download speeds of around 4 mbps in about half our testing locations.
When deciding on a carrier, it’s important to determine whether the service's faster 4G or HSPA+ network is available your area. Consult the coverage maps at the carriers’ Websites for this information.
“Noise cancellation” in smartphones might be better termed “noise suppression.” The phrase refers to isolating the sound of the speaker's voice while suppressing background sounds; noise suppression depends on having the design of a phone’s voice microphone (or microphones) work in concert with sound-shaping technology in the phone’s chip set.
Earlier phones employed various methods to achieve noise suppression, but newer smartphones like the iPhone 4 use two microphones—one to listen to the speaker’s voice and another to listen to ambient sounds like street noise. The first microphone is situated at the bottom front of the phone near the speaker’s mouth; the second is located on the top edge of the phone. Software in the phone’s audio chip set creates a profile of the ambient sounds detected by the second mic, and then subtracts that aural profile from the sound picked up by the mic near the speaker’s mouth. The result is a phone call that, at the other end of the line, sounds as though the caller were calling from a land line in a quiet room.
Since people rarely use cell phones in quiet rooms, noise suppression technology is an important feature.
Removable Storage: MicroSD Cards
SD (Secure Digital) cards and their smaller MicroSD and MiniSD memory-card cousins are the types of removable storage commonly used in portable and wireless devices to store data such as video, music, and image files. The main difference between standard SD, MicroSD, and MiniSD cards is their size. According to iSupply, most cell phones that shipped during 2010 used the smallest of the three card types, MicroSD.
If you're planning to store a large quantity of large media files (such as video) you may want to choose the largest-capacity card that your device will accommodate. The capacities of the MicroSD cards used in most cell phones range from 2GB to 32GB. The 2GB cards retail for less than $10; 16GB (Class 4) cards commonly sell for around $50; and 32GB cards can run as high as $150.
The SD Association has established various speed classes for SD cards. These classes represent the minimum speeds required to write various types of data to the card. Following are the most common speeds, together with the types of content they support, according to the SD Association.
Class 2 : H.264 video recording, MPEG-4, MPEG-2 video recording
Class 4: MEPG-2 (HDTV) video recording, DSC consecutive shooting
Class 6: Megapixel DSC consecutive shooting, professional video camera
Class 10: Full HD video recording, HD still consecutive shooting
Gyroscope vs. Accelerometer
Most smartphones come standard with an accelerometer, but only a few also include a gyroscope. Accelerometers help keep track of the position your phone is in; if you turn it onto its side, the display switches from portrait orientation to landscape mode. Accelerometers are also used in certain applications. In driving game apps, for example, the accelerometer lets you steer your car by tilting your phone from side to side.
Gyroscopes permit more-accurate recognition of movement in a 3D space. If you move your phone away from or toward yourself, the gyroscope can detect that motion. The feature is chiefly useful for gamers, as it makes precise motion-based gaming controls possible. In the future, the gyroscope may play a central role in controlling new and different types of apps. But for now, nongamers are likely to be content without this piece of hardware.
Bluetooth and Wi-Fi
Both Bluetooth and Wi-Fi have become common features on smartphones in recent years.
Bluetooth is a wireless technology that enables you to transfer and receive data between two devices at relatively short range--similar to the way two-way radios work. You can use Bluetooth to transfer files between a phone and an accessory such as a headset, or between a phone and a PC--for example, to transfer photos between your phone and your laptop for editing and viewing.
You’re likely to see two flavors of Bluetooth in the marketplace today: Bluetooth 2.1 and Bluetooth 3.0. The practical differences between versions 2.1 and 3.0 involve range and data speed. Bluetooth 2.1 supports very short-range (around 33 feet maximum) radio communication between two mobile devices. Though not ideal for transferring files, it is adequate for creating a wireless link between a phone and a Bluetooth headphone or headset.
Bluetooth 3.0 works across a much wider range and can transfer large files quickly (at a rate of around 24 mbps) via an 802.11 link. Since Bluetooth 3.0 is still relatively new, not all phones and accessories can take advantage of the speed and range that 3.0 offers.
Likewise, Wi-Fi 802.11 comes in several different protocols (a/b/g/n), each with different speeds and a different range. Having Wi-Fi on your phone allows you to connect to your home wireless network and use it to surf the Web, download apps, send e-mail, and perform other tasks. Most Wi-Fi enabled phones will at least support b/g wireless broadcasts (54 mbps for g and 11 mbps for b) as these are the most common protocols and have decent range (around 125 feet).
More-recent (and higher-end) phones also support 802.11 n, the fastest of the protocols (with raw data speeds of 600 mbps), with the largest range (around 230 feet). Be aware, however, that your connection speed is only as fast as the speed supported by the Wi-Fi router that your phone connects to; both devices must support 802.11 n in order to achieve the standard’s higher speed and greater range.