Apple may have added three more megapixels to the iPhone’s camera, but that’s just about the least interesting, and certainly the least important part of the 4S camera upgrade.
The big news is threefold. Lens, sensor tech and processing hardware.
Lens
The iPhone’s lens now has a maximum aperture of f2.4, which not only lets in more light but also allows for a greater separation between subject and background. This shallower field of focus won’t rival an SLR because depth of field is also a function of sensor size. But one look at the sample photos shows that it is a big step up from most any other cellphone camera.
The lens also gets another element, bringing the total up to five. It might seem like putting in more glass would make it harder for the light to get through, but more elements usually equates to sharper, less distorted images.
Sensor
With pixels, its quality, not quantity. While more pixels means you can print bigger images (handy for Apple’s new Cards app), it also means bigger file sizes and often more noisy images as electrons bleed between the tiny, cramped photo sites.
But the 4S is using a new kind of chip, which has back-side illumination. This confusing name just means that all the electronics on the chip are on the back, out of the way. Non-back-side illuminated chips have all the junk on top, where it impedes the light. Thus equipped, Apple claims increased light sensitivity of 73 percent. Not bad.
Another surprisingly technical term mentioned on the product page is “full well capacity.” This is what it sounds like. Each pixel can only accept a certain amount of light before it fills up. When this happens, the light spills over into adjoining pixels. This is called “blooming,” and is a bad thing. A higher capacity means a higher dynamic range. One note: Most of the sample photos on Apple’s site are shot at ISO 64, making even the low-light images pretty noise-free. My guess is that a tripod was involved in some of them.
Processor
The A5 system-on-a-chip in the iPhone 4S turns out to contain dedicated image-processing hardware. This is similar to the “processing engines” found in regular cameras, such as Nikon’s EXPEED and Canon’s DIGIC. (All caps seems to be the rule here.)
This hardware makes the camera a lot faster. While we’ll have to wait to test it in real life, demos show that the camera performs at the speeds of a compact, not a phone. It snaps photos faster and gets them on-screen and ready to see a lot quicker.
It also lets the camera do some other fancy tricks. Face recognition is now possible (up to 10 of them), and I wouldn’t be surprised to see this tie in with iPhoto’s Faces feature to auto-tag people right there on the phone.
It also adds image stabilization — probably electronic, not sensor or lens-shifting — to video. And the video shot is now 1080p. That’s great news, especially as you should be able to edit them on the iPad’s bigger screen.
Editing
While not essential, it’s nice to be able to crop and edit photos right there in the app. You can also rearrange your pictures into albums in the photos app. These are iOS5 features, coming to all devices, and really make the iPhone and iPad independent from a PC or Mac. Of course, this also makes it easier to lose your photos, but that’s what Photo Stream is for.
I already use the truly awful camera in my iPad 2 more than my real cameras, just because I can share them easily. I have also never owned an iPhone. The 4S will probably be my first, thanks to what looks to be a fantastic little camera, and Photo Stream, which will put shots on my iPad, instantly, and ready to edit. I can’t wait
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