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5.00 Megapixels	Non-Zoom	1/3.2 inch size sensor

Apple iPhone 4 Camera User Report

by Dan Havlik, Shawn Barnett, and Zig Weidelich
Posted: 09/12/2011

Smartphone cameras are getting more and more useful as the sensor and optical technology built into these small camera components continues to improve. The Apple iPhone 4's camera in particular has a few specs that will sound familiar to the modern pocket digital camera buff. Its 5-megapixel sensor, for example, is backside-illuminated for better low-light performance, and there's even a moving lens element for actual focusing. So since several of us live with smartphones here at Imaging-Resource.com, we thought we'd run the iPhone 4, one of the most abundant smartphone handsets out there, through our lab and give it a review. Note that we're not covering other aspects of the Apple iPhone 4, except as they pertain to the main, rear-facing camera itself. The iPhone 4 also has a front-facing camera capable of capturing VGA-quality stills and video, however we did not test it.

Many of the gallery images in this story are 600x600 or 612x612 pixels, significantly smaller than the 2,592 x 1,936-pixel images that the iPhone 4 produces natively. Shooting with the Hipstamatic and Instagram apps reduces the resolution to a size more easily uploaded via a cell phone connection. For full 5-megapixel resolution, see our test shots or the rectangular images in the gallery.

 

Shooting with the Apple iPhone 4

by Dan Havlik

I finally discovered what a great image-making tool Apple's iPhone 4 can be during a trip to Italy earlier this summer. Sure, I've been using the iPhone 4's camera on AT&T for over a year now (it's now also available for Verizon users) and have been pleasantly surprised how much better it is compared to its predecessor, the iPhone 3Gs. For one, there's the bump up to a 5-megapixel CMOS sensor in the iPhone 4 compared to a 3MP sensor in the 3Gs. But I don't think I fully appreciated its value until I shot it side-by-side with a more "serious" camera.

The camera in the iPhone 4 is indeed a little more serious itself: you'll find a host of improved imaging features, including HD video recording at 720p/30 frames per second (fps). Previous models offered only VGA video capture. There are also some clever photo effects including a handy HDR function for balancing exposure along with a few other bells and whistles. So, while on paper, I knew that the iPhone 4 Camera was a marked improvement over the previous generation of iPhones -- and most competing models -- it wasn't until going to Italy that I discovered how well it stood up to even dedicated digital cameras.

First off, I'm not going to argue that the iPhone 4 captures better pictures than even most point-and-shoot models. With its miniscule, 3.85mm built-in lens that only offers 5x digital zoom (no optical zoom), the iPhone 4 just can't compete with the basic zooms in even entry-level cameras. But there's more to the iPhone 4 Camera than specs alone.

Along with my iPhone 4, I brought one of my favorite digital SLRs to Italy: the 16MP Pentax K-5. And while the powerful and versatile K-5 produced images that were -- head-to-head -- worlds better than what the little phone and its measly imager and lens could capture, it was really an apple-to-oranges comparison. For all the important moments of our trip -- a visit to the Roman Coliseum, a sunset ride on a gondola in Venice -- I unleashed the K-5. But for most of those quick and candid, on-the-fly grab shots, I used my iPhone 4 camera. And you know what, many of those shots were my favorites of the trip!

Plus, with the 3G and wireless capabilities of the iPhone, sharing images either through email or on Facebook is an incredibly easy and, dare I say, enjoyable experience. Add in the thousands of photo apps available for the iPhone -- most of which offer effects and sharing features that are unrivalled by anything in the latest cameras -- and you have a unique photography experience that's not yet possible with a dedicated camera. Like I said, it's an apples to oranges comparison.

Phoning It In. One of the most awkward things about shooting images with a smart phone vs. shooting images with a dedicated camera, is the ergonomics and layout of the phone. It's simply not designed for taking pictures. (There are some who might argue that these flat, slippery "slate-style" phones aren't really designed for making calls either, but that's a different story.)

With dimensions of 4.5 (H) x 2.31 (W) x 0.37 (D) inches (115.2 x 58.6 x 9.3mm) and a weight of 4.8 ounces (137 grams), the iPhone 4 is a sculpted hunk of glass and metal that feels solid in your hand if a little bit slick. If you own an iPhone, you probably already know that getting some sort of case for it is essential (and that's not only to combat the dreaded exterior antenna problems!). Along with protecting your phone from errant drops, a case, especially one with a textured, tactile feel to it, will make it easier to hold and compose photos.

Getting the iPhone 4 into camera mode is not as fast or as seamless as it could be. Where some rival smart phones have dedicated camera buttons on their external edge, the iPhone 4 is almost button-free. Neither of the volume buttons on the side of the phone will active the iPhone 4 Camera nor will the home button on the front of the phone. Instead, first you need to slide to unlock the phone (if it's gone to sleep), and then hit the camera icon on the iPhone's 3.5-inch, 960-by-640-pixel "Retina" touchscreen.

The iPhone Camera will then take a few seconds to open its simulated shutter (which is more like a large iris) on the display and be ready to shoot. This can be frustratingly slow, especially if you're in a hurry to catch a candid shot. With some practice, it gets easier, quicker, and more intuitive. (The one thing I still struggle with to this day is keeping my fingers out of the shot since the thin edge of the phone doesn't give you much space to grip it.)

Tricks and Treats. Once the simulated shutter is open, you can quickly snap off a photo with center focus by tapping the camera icon. Picture-taking speed is impressively fast on the iPhone 4: I clocked it at about half a second, which is on par to an entry level point-and-shoot with an actual mechanical shutter. (To be even quicker on the draw, a good trick is to keep your finger pressed on the camera icon, and then release it when you want to capture the photo. This allows you to compose and simulate "pre-focus" and then grab your shot.)

Another neat trick with the iPhone 4 camera is the selective focus capabilities on the touchscreen. Prior to shooting your photo, tap the subject on the screen that you want to photograph and the iPhone 4 will shift the focus box to that spot. Though its effectiveness is somewhat limited -- the tiny lens and imaging chip won't allow you to create dramatic background blur behind your in-focus subject -- it's a nifty feature that will help keep off-center subjects sharp. It's also something I haven't seen on most compact cameras.

Another feature I like is the iPhone 4's built-in HDR effect, which captures three photos – one underexposed, one overexposed and one neutral – and then combines them to create an image with better dynamic range. So, for instance, in an outdoor photo with lots of contrast (such as an image of a park with lots of overhanging trees), the shadow areas are brighter and the highlights are toned down to reveal more detail in the shot.

The downside is it takes an additional 4-5 seconds to produce a finished HDR photo after capture, with the phone saving both the original image and the combined shot. Your subject also has to remain still so that all three images are essentially the same. You can turn the HDR feature off, but I keep it on most of the time because I like the results.

The iPhone 4 has a built-in, but rather weak LED flash that I generally find to be more trouble than it's worth. For starters, my results vary dramatically: sometimes the flash blows out highlights on the edges of a photo while casting harsh light on my subject and other times it's too center focused, with the edges of a photo falling off into a vignette. This issue, we surmised, is likely caused by the LED illuminating the iPhone Camera's lens. (The two are set side by side.) The flash fares worst in tungsten light where it can create a blue cast in select parts your images. You can turn the flash on or off or set it to auto. Because of its inconsistencies and generally poor quality, I mostly keep it turned off.

Surprisingly Versatile. Speaking of tungsten light, the iPhone 4 Camera's non-adjustable Auto White Balance (some other camera phones offer several pre-set options for White Balance) does well in tungsten conditions, and is surprisingly versatile. And that's the thing with this confounded iPhone 4: every time you're ready to count it out because of its limited picture-taking abilities, it surprises you by recording a very good photo of a poignant moment.

This is partially, of course, because you're likely to have the iPhone 4 with you more often than your big DSLR or even your compact point and shoot. But it's also because of all the apps. (There, I said it! There's an app for that!) Yes, a big part of the fun of the iPhone 4 is the tremendous number of photo apps you can use with its camera.

I'm not going to go into all of them but with even just a couple of apps in your arsenal -- I highly recommend Hipstamatic and Instagram -- you can turn a basic photo-taking opportunity into something fun and unexpected with the iPhone 4. Along with helping to transcend some of the iPhone 4 Camera's limitations, photo sharing apps -- like Instagram or Chase Jarvis' Best Camera app -- will get your small masterpieces out into world where people can comment on them. (If a photo is captured these days and no one comments on it, does it really exist?)

But Really Now? Yes, yes, I know what you are probably thinking right now: Any photo you capture and run through software is going to improve its quality. And also, if someone is so keen on sharing photos from a digital camera, they can do that easily from the comforts of a laptop or home computer. What's so special about an iPhone 4?

Well yes, some of that's true, and though you have the ability to share it instantly, not everything needs to be instant. But it is indeed more likely that you're going to share an image if you can, right then and there. The larger issue to consider is whether there are there are any image quality issues worth considering. Our lab discovered more than a few while testing the iPhone 4's Camera. Though the iPhone 4 has a pretty good imaging chip for a cell phone -- a 1/3.2-inch backside-illuminated (BSI) CMOS sensor with the wiring on the rear of the chip so it doesn't block the incoming light -- its a mediocre performer in low light. Most any point-and-shot will beat it in low light at ISOs above 400. (We weren't able to illustrate that meaningfully as we normally would, because you can't set a manual ISO with the iPhone 4.)

And while there's enough detail from a well-lit iPhone 4 image to print a usable 13x19-inch print, 11x14-inch prints look considerably better. Overall, reds were soft in our images and contrast was very high. In general, colors were oversaturated. In short there are some images we've shot with an iPhone 4 that aren't even fit for sharing on Facebook.

But in other areas, the iPhone 4 Camera once again surprised us. In lab testing, the right corners of our images were soft at the very outer edge but they were surprisingly good overall. In fact, they were better than most pocket cameras.

Also, our test shots showed virtually no chromatic aberration, which was another pleasant surprise, and only a small amount of geometric distortion: there was some pincushion distortion, but mostly just in the corners.

For macro shots, the iPhone 4 did quite well. It didn't produce a shallow depth of field -- one of the things we prefer when shooting images of flowers and such -- but our test close-ups were sharp over 95% of the frame, which is impressive. On the other hand, the flash only lit up the center of the frame at this distance, and was very uneven.

In HD video mode, which is activated by moving the simulated slider to the camcorder icon on the screen, the iPhone 4 produced relatively smooth footage, even of fast-moving action. While capturing a basketball game, the iPhone 4 didn't get tripped up when we panned and there was none of the herky-jerky effects of some competing models.

My main complaint is that the iPhone 4's 3.85mm f/2.8 lens – which is approximately equivalent to a 29mm lens – crops down when you shoot video. Because HD is shot in 16:9, a reduced capture size is inevitable in a small imaging device, but the iPhone 4 sliced off larger chunks on the top and bottom of the screen compared to some other phones I've shot with.

Overall, though, the iPhone 4 fared a lot better in capturing both stills and video than should be expected in a multi-tasking device that's smaller than a candy bar. Though dedicated digital cameras offer better image quality and an optical zoom lens -- especially if you jump up to a digital SLR -- there are enough good imaging and sharing features in the iPhone 4 that traditional imaging manufacturers should be getting a little bit nervous, and perhaps considering the addition of 3G networking to their cameras to compete. Add in the bounty of fun photo apps growing every day in Apple's App Store and the expected imaging improvements in the next iPhone, and the "traditional" digital camera could be in for some stiff competition in the coming years.

 

Apple iPhone 4 Camera Lens Quality

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Pretty sharp upper left	Sharp at center	Strong blurring lower right

Sharpness: The iPhone 4's fixed lens shows strong blurring in the extreme right corners of the frame compared to what we see at center, but blurring only extends a very small distance into the frame. The center is quite sharp, and the left corners are fairly sharp. Pretty good performance here compared to most wide-angle pocket cameras, but keep in mind this is a fixed focal-length lens, and we don't know how the iPhone 4's lens compares to other camera phones.

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Moderate pincushion distortion; only slightly noticeable

Geometric Distortion: There is a moderate amount (~0.4%) of complex pincushion distortion from the iPhone 4's lens, though it's mostly in the extreme corners. Keep in mind this is a 29mm-equivalent lens, so perspective distortion can be an issue with closer subjects, as can be seen by the elongated mannequin head in our portrait shots below.

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Very Low

Chromatic Aberration: Chromatic aberration is so low, it's negligible. It looks as though the image processor is removing most of it, but we can't be sure.

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Macro	Macro with Flash

Macro: The Apple iPhone 4's Macro mode produces images that contain pretty good detail across the frame, with very little softening in the corners. (Most lenses produce some corner softening at macro distances, so the iPhone 4's lens performs better than most here.) Saturation and exposure is lower in the center of the image, which is a little odd. The minimum coverage area of 3.40 x 2.54 inches (86 x 65mm) is larger than most cameras. The iPhone 4's LED "flash" provides very narrow coverage, resulting in flash exposures with a lot corner shading. It's best to use external lighting, especially at these distances.

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Apple iPhone 4 Camera Image Quality

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Color: Most colors are highly saturated (29.2% oversaturated in our test), especially reds, more so than we see from typical digicams these days. Contrast is also very high. Hue accuracy isn't bad with only minor shifts in most colors, though there is strong shift in cyan toward blue, but that's fairly common. (We think that's done intentionally to improve the color of blue skies.) Whites and grays are shifted slightly toward green and yellow, indicating slightly inaccurate auto white balance. Indoors, dark skintones are pushed significantly toward orange, while lighter skin tones are quite pink. Outdoors, skintones are a little muted and flat.

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Auto WB: Good, though slightly cool

Incandescent: The stock iPhone 4 provides no user control over white balance, however its auto white balance produced better results than average, though with a slightly cool, bluish cast.

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Horizontal: 1,250 lines	Vertical: 1,300 lines

Resolution: Our laboratory resolution chart revealed sharp, distinct line patterns down to about 1,250 lines per picture height horizontally, and to about 1,300 lines vertically, which compares well to 5-megapixel digicams. Extinction of the pattern occurred at around 1,700 lines per picture height. We did notice the iPhone 4's defective pixel substitution doesn't work well on diagonal lines in our resolution target, leaving some dark pixels between the black lines (click on the crops for a larger image).

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6 ft: Bright	16 ft: Very dim
Coverage	Indoor Portrait

Flash: We're not sure if Apple has rated the range of the iPhone's LED "flash," so we took a series of shots from 6 feet to 16 feet in 2-foot increments. At right, you can see the extremes of that test range. At 6 feet, the flash target was reasonably bright, thought the iPhone 4 raised ISO to 640, producing a very noisy image. At 16 feet (which really is too much to expect from even a digicam with a real flash tube, never mind a camera phone with an LED), the exposure was very dim despite the boost in ISO to 1,000, and extremely noisy. There are also what look to be hazy reflections visible from the flash.  As you can see from the bottom left image, flash coverage is quite narrow, even at non-macro distances.

Our Indoor Portrait scene was fairly bright with the flash enabled, as the exposure retained some ambient light by using a relatively slow shutter speed of 1/15 second, with ISO only raised to 125. However the center of the image has a cool tint from the flash, compared to the very warm periphery. At this slow shutter speed, blur due to subject or camera phone motion will likely be a problem.

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1 foot-candle

Low Light: The shot at right shows how well the iPhone 4 performs in low light without a flash. This test shot was taken at a light level of one foot-candle. (The one foot-candle light level roughly corresponds to the brightness of typical city street-lighting at night.) The slowest shutter speed supported appears to 1/15 second, so the resulting image was a bit dim despite the reasonably bright f/2.8 lens and ISO boost to the maximum of 1,000. As you can see by looking at the full resolution version, the image is very noisy at such a high ISO. Considering the source, though, it's not bad.

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HDR Off	HDR On

"High Dynamic Range": As mentioned previously, the iPhone 4 offers an HDR mode which combines three exposures to retain better highlight and shadow detail than is possible from a single image. As you can see, without it, the iPhone 4 underexposed our Outdoor Portrait shot by quite a bit, with the metering system likely fooled by the bright highlights. But with HDR mode enabled, both exposure and dynamic range were very good for this difficult shot.

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ISO 80	ISO 200

ISO: Noise and Detail: Detail is actually fairly good at ISO 80, though luminance noise is quite high. We prefer this over images that have had too much detail smudged away by aggressive noise reduction. The stock iPhone doesn't provide ISO sensitivity control, but we've included a crop from our Indoor Portrait shot here where the phone selected ISO 200. It also shows fairly decent detail for the ISO and sensor size, though both luminance and chrominance noise are quite high. For more on how this affects printed images, see the Printed section below.

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Print Quality:

The iPhone 4's camera produces enough detail to print a usable 13x19-inch print at ISO 80, but 11x14-inch prints look better. Reds are soft, and contrast is very high. Colors are also oversaturated.

ISO 200 shots are a bit rough at 11x14 inches, but look better printed at 8x10.

ISO 1,000 shots are usable at 5x7, but look better at 4x6 inches.

Overall, the iPhone 4's images are surprisingly good at the lowest ISO setting, but noise becomes noticeable quickly as ISO rises. It's understandable, given the camera's status as one small component of a more complex handheld computer and cell phone.

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Apple iPhone 4 Camera Performance

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Sorry, no performance results, as we're not setup to test camera phones without a physical shutter button.

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Apple iPhone 4 Camera Conclusion

Pro:

Con:

Best still and video image quality of any smart phone we've tried so far Huge, growing abundance of photo apps in Apple's App Store enhances the picture-taking and sharing experience. Surprisingly fast simulated shutter response Snaps good quality Macro shots even though there's no dedicated Macro mode Decent sharpness overall 5MP files taken in good light have enough detail to create a nice 11x14-inch print Auto white balance works well Since it's always with you, iPhone gives you more opportunities to capture candid and revealing shots HDR feature improved dynamic range in stills Selective touch focus via iPhone's 3.5-inch touchscreen Easy to quickly share your images wirelessly via email, Facebook, Twitter or other sharing sites Photo and video geotagging Good HD video capture even of moving subjects 3.5-inch, 960-by-640-pixel "Retina" touchscreen is great for reviewing and sharing photos

LED flash is weak and inconsistent Flash produced blue cast in images when shooting in tungsten light Getting the iPhone into camera mode and to first shot could be easier and quicker Reds were soft and contrast was very high in test shots; colors, in general, were oversaturated Heavy noise in low light shots at higher ISOs Significant cropping down in clips when you switch to HD video capture Only capable of digital zooming iPhone isn't ergonomically designed for picture taking; easy to accidentally get fingers in the shot HDR mode takes about five seconds to produce a finished shot No user control over shutter speed, ISO sensitivity, metering mode, exposure compensation, or white balance No image stabilization No burst mode or self-timer

 

If you stack them head-to-head, the iPhone 4 is not going to give a good, entry-level point-and-shoot digital camera a run for its money. The 5MP 1/3.2-inch backside-illuminated (BSI) sensor in Apple's iPhone 4 may be one of the best on the smart phone market right now but it's simply too small in size to compete with what's in a dedicated digital camera. Furthermore, while the iPhone's miniscule 3.85mm lens produced far sharper results than we expected, it's rudimentary, at best, when compared to most cameras.

But you know that already. The iPhone 4 is a device that's primarily designed for making calls, surfing the Internet, and interacting with web-friendly apps. The imaging capabilities are just gravy, right? That's what we used to think until we started turning to the iPhone 4 in more and more picture-taking situations, and found out that millions of others were doing the same. Why'd this happen?

We're not exactly sure. For starters, there's the vast improvement of the iPhone 4 Camera over the imager in the previous model. Then, there's how easy it was to share these nice shots on Facebook and other social networking sites. There's also an immediacy and intimacy to iPhone 4 photos, which, since the phone is with you at all times, occur spontaneously and do a great job of capturing life's candid moments. And then there are all those juicy photo apps in Apple's App store, which make the capture and sharing experience more fun than with "traditional" digital cameras.

Print quality goes from surprisingly excellent at ISO 80 to pretty low at ISO 1,000, but its top ISO achieves what most pocket cameras can, which is at least a 4x6-inch print. We understand why ISO is Auto-only, but it would be nice if the next camera had more controls for ISO and white balance, at least.

The gravy's found in the iPhone 4's surprisingly good HD video capture capabilities, which are as good as anything you'd find in a basic video camera, such as the now defunct but once ubiquitous Flip. So while the camera in the iPhone 4 might not equal what's possible with a good, modern pocket camera, it's pretty darn good, making the Apple iPhone 4 a Dave's Pick.