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Sony Ericsson K750 (ZOOM)

K750 sample (ZOOM)

N90 sample (ZOOM)

Nokia N90 (ZOOM)

Ever since the Nokia N90 and Sony Ericsson K750 were announced, people have been speculating as to which device would take better 2 megapixel photos. Would it be the N90, with its Carl Zeiss designed optics, or the compact K750 with its parent Sony's electronics? Both devices have pretty similar specs when it comes to their cameras: both are 2 megapixel units, both have auto focusing capability, and both have a history of cameras in the family (Sony's digital cameras and Zeiss' lenses). The K750's camera has a slightly wider field of view, and seems to be a bit "faster" than the N90's (meaning it needs less light), but otherwise these two cameras are pretty evenly matched.

While Sony Ericsson's megapixel cameraphones have always been among the best available, I have to admit that I figured that the N90, with the backing of Carl Zeiss engineering, would end up being the superior camera - at least when it came to optical quality.

But that didn't happen.

An odd thing seemed to have happened on the way from the labs to the phone factory. The optical quality of the K750's camera, which is much physically smaller than the N90's camera, turned out to be superior in most every way. What the N90 did excel at, however, was taking photos that were generally more pleasing to the eye and less "digital" looking.

That's certainly not what I had expected.

As I'll show you in the sample photos that follow, the Sony Ericsson K750's camera is capable of resolving finer detail than the Nokia N90 can. This means that small print is more readable, thin stripes stay visible, and subtle surface textures are more easily seen. You'll also see that the K750 inflicts far less lens distortion on the photos it takes.

But on the other side of the coin, you'll see that the N90's colors are warmer and more pleasant looking (if not always the most accurate). The N90 photos also have more color saturation, which makes them pop a bit more. Its exposure settings are, to my eyes, also closer to the ideal in more circumstances. On top of that, the N90 seems to be able to obtain focus more consistently.

So what we have is a case of the electronics company, Sony, coming up with a better lens, and the optics/phone company partnership, Zeiss and Nokia, coming up with better software and post-processing of the images. Exactly the opposite from what I was expecting.

All of the photos for this story were shot at the highest resolution and quality settings that each device offered. All photos were shot with the same white balance settings on both cameras (auto, cloudy, incandescent, etc). While I tried to make things as equal as possible, this is far from a scientific experiment. The devices were hand held, lighting varies, and it is possible that either of these devices is a particularly good or bad example of its kind. I'm not an optics engineer, but I am a hardcore photographer with many years of experience. Take what I say for what it is: personal opinion. Your mileage may vary.

First up in our comparison: Lens Distortion.

Lens Distortion

K750 distortion (ZOOM)

N90 distortion (ZOOM)

Probably the single biggest problem that the Nokia N90 faces is lens distortion. Photos taken by the N90 exhibit a decent amount of barrel distortion as well as other types of distortion. Barrel distortion is where the sides of an image appear to bulge out when compared with the corners. This type of distortion appears similar to what you see when you take a photo of somebody with a wide angle lens from a very close distance. Noses appear larger and more bulbous, people appear heavier. The distortion gets worse in the N90's macro mode. The K750 also suffers from barrel distortion a bit, but it is generally not enough to be noticed except in certain types of photos with lots of horizontal and vertical lines (such as the train tracks and brick wall).

The opposite effect is called pincushion distortion. Neither phone exhibits this problem.

In order to make auto focus cameras that fit into the tight confines of a mobile phone, engineers have to make use of some fancy lenses. In the case of the N90, there are 4 separate lens elements inside the camera. The outer most one is made of optical glass. The other 3 are made of plastic, one of which is what is termed aspherical. This means that the lens faces are not curved in a regular manner. A normal lens is shaped like the surface of a ball (or a small part of that surface). An aspherical lens has an irregular shape that is engineered to counter one or more issues inside a lens group. A Carl Zeiss rep told me that the N90 uses a particularly extremely shaped aspherical element in its lens to counter issues with focusing and such in a small space.

This is what I believe we are seeing in the N90's distortion. While I would wager that the K750 also makes use of an aspherical lens, since they are common on many cameras, I believe that the N90 might be suffering from a bit of over-engineering in this regard. The result is very obvious image distortion in what is a much physically larger camera - something that should have made things easier in the design stage.

While I think you can safely argue that the example photos on this page are of somewhat extreme situations that stress the cameras, you have to give credit to the Sony Ericsson team for dealing with the problem better.

The photos of the brick walls were shot on a cloudy, rainy day. While the N90's photo shows a lot of distortion, you'll note that the color looks quite good when compared to the very orange looking K750 photo. This is due to the cameras' white balance system, which is the next topic of discussion. Both cameras were set for "cloudy" lighting conditions in these photos.

Up next: White balance

K750 distortion, cloudy WB (ZOOM)

N90 distortion, cloudy WB (ZOOM)

White balance

K750, auto WB (ZOOM)

N90, auto WB (ZOOM)

While the N90 takes a beating on image distortion, it rebounds strongly when it comes to the overall color of the photos. White Balance ("WB" in the photo captions) is the term that defines the temperature of the light in a situation. The human eye excels at adapting to different color lights and looking at them all as being roughly white. Electronics don't work that way, they see the subtle shades of red, green, and blue that define light's temperature, or white balance.

To give you an idea, take a look at the photos above. These two photos were shot under halogen studio lights that have a color temperature of about 3200 degrees Kelvin (how light is measured). Like other incandescent lamps, halogen lights tend to make scenes look "warm", or orange-red in color. We've all see a thousand indoor photos that show what I am talking about here. White napkins and table cloths look reddish, people's faces look more tan, everything looks as if it were being lit by fire light (which is very red indeed). These photos were shot with each camera set to its automatic white balance setting, which means that the camera circuitry has to look at the image and make an educated guess as to what color things really should be.

In the photos above, the color wheel chart's center is white. The card that is attached to the wheel is a middle gray (18% gray card, for those photographers out there). If you were to take one of the photos and load it in a graphics editor, such as Photoshop, you could take a color sample of the color of the gray card. The sample should, if everything works perfectly, report equal amounts of red, green, and blue in that gray. In this test, the N90's white balance nearly nails it - something that most dedicated cameras (including my SLRs) fail to do. The K750's photo, on the other hand, is seriously lacking in green, and even more so in blue. The photo is ok, but far from being accurate.

K750, indoor WB (ZOOM)

N90, indoor WB (ZOOM)

In the examples directly above, both devices were configured with their white balance settings set for incandescent (or "indoor") lighting. In this case, the K750's photo looks perhaps a bit better, but now is very cool (blue) looking. This means that the camera was expecting the light to be even redder than it was in this case. While it looks poor here, it would probably be effective for low wattage light bulbs, which run at lower temperatures than the lights I use in the studio. The Nokia N90's white balance setting seems set for a more traditional type of incandescent light, and as such totally nails the white balance on this photo.

Where the N90 also seems to have a bit less trouble than the K750 is in situations with mixed lighting. In a room with overhead lighting in addition to window lighting, the K750's cooler world-view tends to detract from a photo - if only by a little bit.

The photos below show a table and large bowl in a mixture of incandescent and outdoor daylight lighting. Both photos look quite good, but the N90's rendition is more accurate when I compare it with the actual scene in my dining room. So while it loses to the K750 in terms of distortion, the N90 reigns as one of the best cameraphones on the market in terms of white balance that I have used.

Next up: Detail/Resolution.

K750, indoor WB (ZOOM)

N90, indoor WB (ZOOM)

Exposure

K750, auto WB (ZOOM)

N90, auto WB (ZOOM)

This part is probably the most subjective part of this comparison. In general, both the Sony Ericsson K750 and the Nokia N90 do a good job of exposing photos. But again, unlike our eyes, which can adapt quite easily, the electronic circuits of a digital camera have a harder time coping. We have no problem seeing the bark on a shaded tree one moment and the thin wisps of clouds in the sky on a sunny day the next. Our pupils dilate our eyes in order to adjust to the amount of light present, always giving us the amount we need to see things well.

The problem with a camera is that it only gets one chance to record the entire scene. It needs one setting to let you see the bark as well as the clouds. Like our pupils, the camera adjusts the amount of light it receives: either by adjusting the size of the opening behind the lens, or by changing the amount of time it "looks" at the subject. If the opening is half as big, the time needed is twice as long. But unlike our pupils, that one pair of settings has to work for both the bright light of the clouds as well as the dark areas of the tree trunk. The camera looks at everything at once and records what it can.

Unfortunately, this means that compromises have to be made and that details get lost. The clouds in the photo are either too bright to make them out, or the bark of the tree is too dark to see its texture. Guessing at what the real subject of a photo is, and exposing the photo accordingly, is one of the most complex things that a camera has to do. And there is no such thing as a "perfect" exposure in some situations. I might prefer the bark detail be visible, you might want to see the clouds.

Look at the photos at the top and bottom of this page and make up your own mind. My opinion is that the N90 does a better job of picking out the important parts of a scene and making the best compromise in terms of exposure. In the case of the photo above, the wine opener is a bit darker than perhaps optimal, but the details of the window dressings in the background are preserved.

The scene below is much more difficult. The N90 went with a brighter exposure that caused the cloud detail to be lost, but made the rest of the photo perfectly visible. I feel that this was the better decision than that of the K750, which choose to make the entire scene darker in order to preserve cloud background detail. You might argue it differently.

Up next: Contrast and focusing.

K750, auto WB (ZOOM)

N90, auto WB (ZOOM)

Contrast

K750 (ZOOM)

N90 (ZOOM)

The K750 seems to have more trouble managing contrast than the N90 does. Higher contrast means that photos have whiter whites and blacker blacks. Think of it as comparing a sunny day with an overcast day. The sunny day, with its bright sky and dark shadows, has more contrast. Contrast is one of the things that makes images look sharp. In the case of the resolution chart 2 pages back, the whites on the K750's photo were about 6 times brighter than the blacks. The N90's whites were only about 3.5 times as bright as its blacks. The K750 managed contrast well there, but you will see in the photos above, the N90 managed it better overall in a real world situation.

For general photo snapping use, I believe the N90 does a slightly better overall job of managing exposure and contrast. Its lower contrast and slightly softer look give the photos less if a digital looking appearance.

Focusing

Both the Sony Ericsson K750 and the Nokia N90 have auto focusing lenses, as we have discussed. They are both also capable of focusing on fairly close as well as distant objects pretty well. But in my experience, the K750 sometimes has trouble getting a proper focus in situations that I consider to be quite simple.

Take, for example, the photos above and below of the peppers. Originally shot for the white balance test, they ended up pointing out an odd problem with the K750's focusing system in some situations. After multiple attempts, the K750 was unable to get an accurate focus lock on the peppers. It thought that it had focus, and reported as much, but it was always wrong. Every time.

The normally sharp K750 produced soft photos in this situation. Look at the card with the 99 cent price written on it. If the card wasn't sitting on a bunch of red peppers, you might not be able to tell that the card reads "Sweet Red Peppers". The Nokia N90's take on the scene looks much sharper. The N90's white balance is also more accurate, but in an odd contradiction of what I just stated on the prior page, the photos seem a bit over exposed.

Up next: Low light and the conclusion

K750, fluorescent WB (ZOOM)

N90, fluorescent WB (ZOOM)

K750, auto WB (ZOOM)

N90, auto WB (ZOOM)

Low light

K750 (ZOOM)

N90 - red blotches (ZOOM)

When it comes to low light performance, the Sony Ericsson K750 handles things a bit better than the N90 does. If you look at the photos of a rather messy desk drawer above, and peer at the unlit part of the drawer that is still under the desktop, you should notice a lot of blotchy color in the N90 photo where things look fine (if darker) in the K750 image.

Look especially close at the reds in the Altoids can, and the area above that. The K750 also gets noisy when the lights turn low, but it maintains its composure better, overall, than the N90. But other than that dark area, the N90's photo has much better color saturation and white balance.

Both devices have bright LED assist lights for low light situations, both should be best avoided. The color of the "flash" is too blue, and unless your subject is at just the right distance from the phone, the photos come out either totally washed out or very, very dark. Both phones have decent night modes, but in order to work, the effective shutter speeds they use are too slow to capture any kind of motion at all, resulting in blurry subjects. If you are taking a photo of a still object and have steady hands, you might be in luck. But in general, don't expect to use either of these devices for decent photos in low light.

Conclusion

Both the Sony Ericsson K750 and Nokia N90 are capable 2 megapixel digital cameras. Neither is as good as a relatively inexpensive dedicated point and shoot digital camera, but they are "good enough" for many situations. One of the golden rules of photography is "a camera left at home will never get the shot." In other words, having a camera with you, even if it is not a pro level digital SLR, is the first step to getting the photo you want. A camera that you leave in a desk drawer at home is of no use.

That is what makes both of these cameraphones so great to own. Most people never leave home without their phone. If their phone is a K750 or N90, they won't ever leave home without their camera, either.

So which one is better? That's a hard question to answer. Each device has its strengths, even if they are not the ones we would have guessed. But while I prefer the color and white balance of the photos taken by the N90, in the end, I'm a stickler when it comes to lens sharpness and distortion. With that in mind, I have to give the nod to the K750, even if it is only by a slight margin.

Look at the photos yourself and make your own decision as to what looks best, and what flaws you are willing to live with. In either case, you'll have a good time snapping photos with either device no matter where you find yourself.

You'll find a few more sample photos taken by the Sony Ericsson K750 and Nokia N90 on the following page.

Sony Ericsson K750 (ZOOM)
Nokia N90 (ZOOM)

Sony Ericsson K750 (ZOOM)

Nokia N90 (ZOOM)

Sony Ericsson K750 (ZOOM)

Nokia N90 (ZOOM)