Image Quality and Performance

The Nexus 5 is a very fast smartphone: it uses the same Snapdragon 800 quad-core processor that powers the top-end Samsung Note 3, Sony Xperia Z1, and the brand new Nokia Lumia 1520. Just about everything happens as fast as you could want it to.

Everything, that is, except a few things that are critical to mobile photographers. The camera app takes a sluggish second and a half to come to life after you tap its icon, and for reasons that defy the imagination, “jumping” to it from the lock screen shortcut adds at least another second to that. Occasionally the phone seems to ponder opening the camera for a few extra seconds, just to infuriate you. [Note: Following the Android 4.4.1 update, the Nexus 5’s camera app is substantially more responsive, with a second shaved off the start-up times.]

Once the app is up, focus is on the slow side of normal: it doesn’t feel broken, but it won’t impress you. [Note: The Android 4.4.1 update also improves focus speed.] In good light it’s usually accurate, but in lower light (indoors with subdued lighting, for example) it fails to lock or misfocuses more that most phones.

Qualcomm's Snapdragon 800 processor provides plenty of oomph for smooth and responsive overall operation but unfortunately the camera app often feels a little lethargic.

Few phones offer truly speedy focus, but onerous shutter lag (excluding focus time) is something we’ve left largely behind us, at least at the high end of the market. Apparently the Nexus 5 didn’t get the memo, as it exhibits close to a half-second of shutter lag when prefocused. For landscapes and even posed portraits this isn’t such a big deal, but for candids and actions shots, it’s enough to be frustrating. [Note: Shutter lag is much reduced following the Android 4.1.1 update — it’s still a little longer than we’d like to see, but it’s no longer infuriating.]

If you miss the shot, you can’t take another one right away. The very fastest shot-to-shot time you’ll see is about half-a-second, not bad though far from instantaneous. However, that speed is variable and sometimes runs closer to a second. The bottom line is that if you hit the shutter immediately after taking a picture, the camera will usually ignore the input. By itself, this wouldn’t be a terrible state of affairs, but in the Nexus 5’s case it contributes to the overall laggy feel of the camera.

Perhaps unsurprisingly, the camera app doesn’t offer a burst mode. There’s even an irritating 2 to 3 second lockup when toggling the HDR+ mode on and off. It’s bizarre how a phone that otherwise runs like a thoroughbred can stumble so badly when the camera is involved.

Phone cameras have made great strides in general responsiveness over the last few years, making them feel much more like “real” cameras. The Nexus 5’s operational speed, while not dismal, is a step backwards compared to the best of the competition. The lock screen shortcut lag smells like a software problem, and Google has reportedly promised an update to address some of these issues, but we were unable to independently confirm that or learn which aspects might be slated for improvement. If and when Google releases a fix, we’ll revisit this topic. [Note: Thanks to the update, the Nexus 5’s camera app is now middle-of-the-pack in terms of responsiveness and speed.]

Daylight, Low ISO

In good light, the Nexus 5’s camera delivers generally pleasing results. Detail levels are in line with a solid 8MP performance. Contrast is sometimes a little lower than we’d like.

Colors are mostly pleasant, ranging from a bit muted in overcast light to heavily saturated in bright sunlight (skies in particular are sometimes rendered an electric blue).

Exposures are generally appropriate in terms of brightness, with the phone making reasonable compromises when faced with high-contrast scenes. However, the Nexus 5’s ISO and shutter speed choices can be inscrutable. Sometimes, as you’d expect, the phone does its best to keep ISOs low, relying on its optical image stabilization to enable sharp images at slower shutter speeds. But sometimes it keeps shutter speeds higher than necessary (1/100 sec or 1/120) and raises ISO to compensate. There doesn’t seem to be any rhyme or reason to the choices: static scenes may get the high-speed treatment, while scenes full of movement may get a low-ISO, low-shutter speed exposure. We didn’t observe any catastrophic examples of this (like shooting a bright scene at ISO 800) but any time a phone camera pushes up ISO unnecessarily, it’s a concern.  

HDR+ mode produces images that are both more saturated and tend to have higher contrast (despite exhibiting wider dynamic range) than normal shots. Edge definition is also improved through sharpening. On just a few occasions during our testing, HDR+ shots were grossly overexposed, presumably due to a software glitch.

The lens on our sample was very sharp, with just a hint of softness visible at 100% viewing in the top left corner. The lens was reasonably resistant to flare, with bright light sources in dark scenes occasionally causing small flare artifacts. Chromatic aberration (color fringing on high-contrast boundaries) isn’t a problem, though processing artifacts we spotted in a few images suggest this is thanks to software cleaning things up.

In good light, the Nexus 5 delivers pleasant, balanced images. At base ISO, there’s a reasonable amount of detail in darker, lower contrast areas.
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Areas of dark, plain tone show visible noise when viewed at full magnification, but not more than most of the competition. Here we also see how deeply saturated skies can be.
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Color balance in daylight is generally good, with nicely rendered skin tones.
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In cloudy conditions, colors are cool and muted, and recorded contrast drops.
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The same scene shot in HDR+ mode shows better saturation and more detail and contrast.
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Blown highlights remain a constant of mobile photography. Using HDR might have helped here, but it can’t work miracles.
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Chromatic aberration isn’t normally a problem, but on rare occasions remnants are visible, suggesting it's probably removed by software.
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Low Light, High ISO

Thanks to its optical image stabilization, the Nexus 5 turns in a very good low-light performance as long as key subjects aren’t moving. When the lights go down, the phone drops shutter speeds to as slow as 1/6 sec, and with OIS keeping things steady shake-induced blur is rarely a problem. Moving objects, on the other hand, will show motion blur. There are times (candid party shots, for example) when it would be nice to raise shutter speed by increasing ISO. [Note: Following the 4.4.1 update, the camera now prioritizes higher shutter speeds in low light situations. For a detailed discussion of the new exposure policy, see our report on the update.]

In normal shooting mode, the ISO range maxes out at the oddly arbitrary 1624. In HDR+ mode, that stretches to 3200. Combined with slow shutter speeds, this means that you can take a picture (though maybe not a pretty one) of virtually any scene with enough light to see by. 

The phone’s noise reduction is restrained at the base ISO of 100 but quickly gets aggressive as sensitivity rises. The upshot is that images show relatively little noise, even as ISO breaks 1000, but detail takes a heavy hit. Overall, though, the Nexus 5 strikes a reasonable balance between noise reduction and detail retention.  

At ISO 243, about 1.3 stops above baseline, the Nexus 5 retains very good detail. The 1/8 sec shutter speed used here results in a sharp image thanks to OIS, but moving objects would show blur.
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At ISO 400, noise is still under control, though detail, especially in the darker parts of the scene, is clearly under attack.
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The Nexus 5 exposed this indoor portrait at ISO 541 for 1/8 sec. Noise is well controlled and there’s no visible chroma blotching under the artificial lighting, even in very dark areas. This comes at a cost of significant detail in low-contrast areas like the subject’s face, but the overall effect at reasonable magnifications is still very satisfying.
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Dimmer conditions push the ISO to 1167 here. Luminance noise is visible at screen resolutions and there’s a hint of chroma splotching if you look for it. Colors are starting to look washed out. Arguably, this scene could look better if exposed a little darker.
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At 1/6 sec and ISO 1624, we’ve hit the brightest exposure the Nexus 5 can make with this very dark scene. Fine detail is gone, but the image holds up well at screen resolution and is more than good enough for web sharing. Edges are well-defined thanks to sharpening. Chroma noise is impressively controlled, essentially invisible at moderate magnification.
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Flash

The Nexus 5 has a single LED flash. The scene needs to get really dark before it fires in auto flash mode, but it works well for those near-darkness bar portraits. Skin tones look fairly natural, with just a slight yellowish cast. The LED is powerful enough to light people at normal portrait distances and keep ISO at moderate levels, but obviously won’t fill a room.

The Nexus 5 produces reasonably natural colors with its LED flash, which is powerful enough to light people at normal portrait distances.
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Because the auto flash mode is so conservative, you might be tempted to force the flash on in order to get a more detailed, lower-ISO image. We don’t recommend this, however, since the flash illumination doesn’t seem to play well with ambient light. The result is generally a Smurf-tinted subject. If you do end up with a heavy color cast, the Gallery app’s one-touch Autocolor function does a good job of restoring skin tones to something approximating human.

Forcing the flash on when the Nexus 5 would rather just boost sensitivity tends to produce a nasty blue color cast.
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