It's only 5 megapixels, but during iPhone 4's launch, Steve Jobs specifically noted that when it comes to image quality it's not all about how many pixels you have. The backside-illuminated (BSI) camera sensor with large pixel sizes allows it to deliver excellent image quality under normal lighting conditions.
There's no optical zoom on the iPhone 4 and the size of the image sensor is smaller than the tiny ones used in compacts, but this new camera is approaching point-and-shoot quality, and may drive some people to ditch their pocket cameras and look to the newest iPhone for everyday snapshots.
After spending a few hours walking around San Francisco, I'm pretty pleased with the images. Under optimal bright lighting, it's outstanding and even in low light, you can see how the backlit sensor helps by sending more light into the sensor. The blacks look very good, avoiding the common grain, noise, and discoloration common in point-and-shoot cameras from just a few years ago.
Take a look at some of my test shots from the streets of San Francisco with the iPhone 4. (These images were opened in Lightroom to crop and straighten, but no sharpening or color correction was performed.)
One of the most notable elements of these images from the iPhone 4 camera is the clarity of the blacks. Even in the shadows at the bottom of the image, the blacks have great tone and color range. Often, mobile phones suffer from excessive noise or color distortion in the black tones, but the iPhone 4 seems to handle the low end of the light spectrum well thanks to the bright backside-illuminated (BSI) sensor.
Inside San Francisco's Ferry Building, a foodie's heaven, soft light from skylights gives these heirloom tomatoes excellent lighting, and under these conditions, the iPhone's camera performs very well.
I attempted to use the flash on this photo, and like many mobile phone cameras, it had trouble balancing the color temperature differences between the flash and the natural sunlight, resulting in odd yellow and green tones.
Bronze medallions embedded in San Francisco sidewalks take visitors along the Barbary Coast Trail, a walking tour that connects the city's most important historic sites. The detail in this photo is impressive.
Looking down on Union Square from the top of Macy's. In the center of the photo is a tall column topped with a statue of Victoria, goddess of victory, a monument commemorating the victory of Adm. Dewey in 1898 at Manila Bay during the Spanish--American war. In the next photo, I zoomed in on the top of the statue from the same location.