iPhone 4 camera

The iPhone 4 has a 5 MP, backside-illuminated autofocus camera with LED flash. In my experience, the camera is good enough for everyday use and very handy to have around you all the time.

I just learnt about CCDs last semester, so I know what a backside-illuminated CCD is. A normal CCD is a block of silicon that converts light into electricity (actually the light frees electrical charges). On the top is wires to move that electricity to be measured. Unfortunately, the top is also the direction where the light comes from, so the wires block some of the light. In a backside-illuminated CCD, the light comes from the bottom, which is not blocked by wires. This makes more sense, but the reason it wasn't used before is you have to thin the silicon very precisely for the light to be detected. Remember, the light comes from the bottom, but the electricity has to appear at the top.
Actually, the first method isn't that bad. The human eye also uses the same design. The blood vessels actually block the retina. Some people use this as an argument against intelligent design. Anyway, maybe there's an advantage to this method we haven't discovered, and the next generation of CCDs will go back to front illuminated? Technology tends to cycle, after all.

• GPS lock is nearly instantaneous
• Photos displays photos on a map
• Macro mode, up to 10 cm close. I use macro more than I use tele.
• The camera is hard to use with 1 hand
• The silver bezel and the camera lens itself is exposed. I'd prefer them to be under the back glass, like the LED flash, so they'd be protected by my screen protector. At least the back glass and camera lens are easily removed and replaced.

Comparisons
Front camera

Taken with my Nokia 6120 classic

iPhone 4

These 3 images are all displayed at full resolution. The iPhone 4 has a higher resolution front camera. I guess if you have a big screen, you need a high resolution for video calling. It seems less noisy too, but that might just be the light. It's not fair comparing the iPhone 4 with a 3 year old cheap phone, but that's all I have. Just don't take the comparisons too seriously. They're all self-portraits, but hey, that's what front cameras are for. It appears slightly better than the iSight, which is of the same resolution.

iSight on MBP

Back camera - this is serious business.
Good lighting

iPhone 4

HTC Magic, 3 MP autofocus

Nokia 6120 classic, 2 MP fixed focus

Under good lighting, all 3 cameras perform well, even the 2 MP fixed focus 6120. The iPhone 4's picture is of a friend's experiment, which was one of the first pictures I took with my iPhone. What impresses me is the detail in the picture - you can see the bubbles in the liquid, and you don't even need a dedicated camera for that! The HTC Magic's camera's quality is good, but the worst part is the shutter lag. In a time when shutter lag is measured in 0.1 of a second, the Magic has a shutter lag of up to 3 seconds, which is simply unacceptable.

Poor lighting - will the backside illuminated sensor confer an advantage?

iPhone 4, ISO 800

HTC Magic. No image data - no ISO, shutter speed, aperture or focal length.

Nokia 6120 classic

Image quality drops significantly under low light. The person in red in the iPhone image (that's Dr Karl Kruszelnicki) is not very clear, maybe due to noise, camera shake or poor focusing at long distances. The Magic's image looks less noisy, but it's hard to tell without knowing the ISO. (I just discovered you can search by ISO rating in OS X) The image quality from the 6120 is poor. Looks like the system is really amplifying the CCD signal.