Features of a good Camera Smart-Phone

There are lots of good camera smart-phones available in the market, but they are either costly or very difficult to finalize which one is the winner of all. We would like to share our basic understanding and features of good smartphone camera to help you yourself judge weather the smartphone camera meets your needs or not?

Today, every smart-phone company gives a lot of details including the minor ones, which sometimes the customers are not able to understand completely. Companies boasts and show-off by the providing the camera specs and features (which is good) to increases their customer base and as well as their sales. Some of the features mainly comprises of the Mega-pixel count, type of flash, aperture (f value), image stabilization (if any), processors and software, lens and others. Now lets us have a look at these features and know what they mean and their significance while clicking a photo.

Mega Pixel count

We usually presume that a greater count of mega pixel gives a better image with adequate sharpness. Today though, this assumption has come to haunt the camera manufacturers and people in both Canon and Nikon who are one of the best camera manufacturer, are the first to point out that a 5-megapixel resolution is big enough to give a clear print-out on an A4 sized page.

"The current thinking about megapixels is highly misleading," a technical officer at Nikon, India says. "As a measure of resolution, it just tells you how big the image you're taking is. How much can you crop, without pixelation. That's when the original image is too small and you zoom, so it starts to look blocky. But with a 16-megapixel image, even if I crop to 50% of the image, it won't look pixelated when printed."Have a look at the difference of size of camera picture of Iphone 5s (8 megapixels), Nokia Lumia 1020 (41 megapixels) and Nokia Pureview 808 (41 megapixels).

The image is formed when the light falls on the sensor. If the sensor size is big then the image will be more detailed, even when you crop into smaller parts of the image and enlarge them.

Auto Focus

If the smartphone has auto focus, then the images will be sharp giving a good amount of detail when compared to a device having fixed focus. Auto or manual focus gives the ability to the handset to focus on different objects placed at different distance from the camera. But sometimes, the auto focus increases the time taken to click a photo. New techniques have been invented to reduce this time.

CDAF: Contrast Detect Auto Focus (traditional Auto Focus) In this, the camera software starts the lens to move and scan through its entire range of available focus points, then it returns to whichever settings that provides the sharpest focus. Contrast detection achieves precise focusing but takes a long time because the motor has to keep moving to find the highest contrast.

PDAF: Phase Detect Auto Focus (HYBRID), phase detection is the process whereby the phase difference of the objects at the imaging plane is calculated to find the distance between the motor’s current position and the position required to bring the object into focus. Phase detection is fast and takes a shorter time, but the phase difference does work properly in low light and is affected by noise.

Laser Auto focus: The laser auto focus is more accurate and faster than CDAF and PDAF. It uses a beam of infrared laser to detect the difference between the object and the camera, and helps the camera focus, blazingly fast. A number of high and mid-range devices are using laser focus in imaging.

Aperture

Aperture is essentially an opening of a lens's mouth through which light passes. It controls the amount of light which reaches the sensor. A bigger aperture hole lets your smartphone camera sensor gather more light, which it needs to produce quality images.

The size of a lens aperture is denoted by its f-number, which is calculated using the lens focal length to the diameter aperture. This means that a larger f-number refers to a smaller opening, and therefore less light gets through. That’s why smartphone camera manufacturers boast about larger apertures, with smaller f-numbers.

As you move along the F-stops F1.4, F2, F2.8, F4, F5.6, F8, and so on, the value of aperture halves and half the amount of light passes through on each stop.

Stabilization

The stabilization is present only on a few mid-range and most of high end smartphone support this feature. This feature helps to reduce the blur and noise and increase sharpness in a photo or a video. Stabilization is of two type:

OIS: Optical image stabilisation, in this technique the image is stabilized by varying the optical path of the sensor. The camera sensor is placed on a set small springs which compensates the shaking of hand using the Gyro-scope sensor, by moving the camera sensor in opposite direction. This is real time compensation and therefore no image degradation takes place. Different manufactures have different names for their OIS Technology, for example, PureView by Nokia, Ultrapixel by HTC, etc.

EIS: Electronic image stabilization works on a different principle and here the effect takes place at programming level after the optical signal has been converted to a digital signal. In EIS the processor breaks down the image in to small chunks and then compares it to the preceding frames. It determines whether the motion was a moving object or an unwanted shake and makes the required correction. This might lead to image degradation; however, the effect is fairy less when your camera device has fairly large resolution. Now here is the part where megapixels do matter.

ISO Levels and camera features.

When you are taking a picture on your phone, there are three major components: namely ISO, shutter speed, and aperture. These three components each have advantages and disadvantages, so your smartphone will try to adjust some of these components to compensate for different lighting environments so that you get the best image every time.

Software: software or the camera UI also plays an important part by providing different shooting modes like slow-motion video, bookeh effect(background blur), timerm beautify software and more.

Sensors: 

• BIS or A back-illuminated sensor, also known as backside illumination (BSI or BI) sensor, is a digital image sensor that uses a novel arrangement of the imaging elements to increase the amount of light captured and hence improving low-light performance. This technique is sometimes used  in specialized roles like low-light security cameras and astronomy sensors, but was complex to build and required further refinement to become widely used.
• CCD (Charge Coupled Device) sensors convert pixel measurements sequentially using circuitry surrounding the sensor. CCDs use a single amplifier for all pixels. CCDs are manufactured with specialized equipment and therefore they are costly. There are some distinct advantages to a CCD sensor like less noise and generally higher quality images, particularly in low light conditions.
• CMOS (Complementary Metal Oxide Semiconductor) sensors convert pixel simultaneously, using circuits on the sensor itself. CMOS sensors use separate amplifiers for each pixel. CMOS sensors are commonly used in DSLRs as they are fast and cheap. Both Nikon and Canon uses CMOS sensors in their high-end DSLR cameras.

ISO is a term that carried over from the film age to the digital age, but all you need to know is that it’s a measurement of how sensitive should be the sensor to light. The higher the number goes, the more sensitive the sensor becomes to light. So, while ISO 6400 is a lot more sensitive to light than ISO 100, an image taken with that high of an ISO will have a lot more noise.

Shutter speed refers to how long the shutter is open to expose the sensor. The longer the shutter is open, the more light is exposed to the sensor. The problem with shutter speed is, if it’s open for too little time then the sensor might not get enough light exposed on it, leaving you with a darker image. And if it’s open for too long, then your image is more likely to be blurred because of your movement while holding the camera or overexposed because there was too much light.

Sensor and Flashes

Flash plays an important part while clicking a photograph, especially in low light. Though different flashes are available in smartphones, all have different purposes and advantages.

Xenon Flash: (A Brighter & Faster Flash Technology) Xenon offers a much brighter burst of light than LED does. This means that images are more clearly lit, the flash has longer range and that shutter speed can theoretically be increased. Both of these two reduces blur, which commonly hampers low lit conditions shots. A xenon flash consists of a small glass tube filled with xenon gas. When a very high voltage current of electricity is applied, the tube emits a very bright, but very brief – flash of white light.

LED Flash: Today, LED is the most common type of flash used in smartphones. LED flashes are energy efficient and much advanced if compared to earlier lighting technology. LEDs can be strobed faster than any other light source, including xenon. Also, they can be turned on during a video shoot too, which is a plus point when compared to Xenon flash.