Used as a camera, the main strength of the iPhone 5 is its ease of use. That's not to say it's under-specc'd by any means, but the default camera app is geared towards hassle-free shooting. Look under the hood, however, and there's some neat functionality waiting to be exploited, including a two-shot HDR mode, AE/AF lock and a very effective Panorama function, as well as in-camera editing of captured images.

Touch to AF/AE Lock

The iPhone's Camera app offers fully automatic exposure, which biases AF and exposure towards faces, if any are detected in the frame. Overriding the camera's automatic AF and exposure decisions is easy though, you just have to use your fingers.

To set focus and exposure manually, simply touch the area of the scene that you want to be the target. The camera will then set focus and exposure from this area. If you've used an SLR camera, you're probably familiar with spot metering - same thing.

If you want to lock exposure and focus, do the same thing - touch the area of the scene that you want to lock from - and simply hold your finger in place for a moment. The AF square will 'pop' a couple of times and a badge, 'AE/AF lock' appears at the bottom of the screen. You can then recompose your shot, totally change the framing, and exposure and focus won't change. This is especially useful in video mode, and in combination with HDR, when it comes to really tricky exposures (see below). 

HDR Mode

If you're faced with a tricky lighting situation and flash isn't an option, the iPhone 5's HDR function could be the answer. This combines two images - one 'normal' exposure and another, darker shot for highlight detail - to create a single exposure.

HDR Off (conventional exposure)

You have the option (activated in the main General Settings dialog) to save two images per capture in HDR mode - the HDR version, and the original, 'straight' exposure. This uses up more space on your phone's internal memory but can be useful every now and then, especially when shooting moving subjects.

HDR isn't only useful for landscapes, it's also handy for ensuring that highlights don't clip on reflective subjects, like this lock.
This is the blended (HDR) exposure and as you can see, there's no clipping on the shiny side of the lock, resulting in a better-balanced exposure. 

The way that the iPhone creates HDR images means that moving scene elements can show slight 'ghosting', despite the phone's (usually sucessful) attempts to blend the captures seamlessly. Normally though, the HDR exposure is spot-on. Indeed, assuming your scene elements are reasonably static, we've seen HDR images from the iPhone 5 and 4S that rival many 'proper' cameras in terms of tonal range.  

For this shot, in extremely tricky lighting, I locked exposure from the dock in the foreground and activated HDR  mode to balance the tonal range as much as possible. 
One downside to using HDR mode is that you can occasionally get 'ghosting' caused by two exposures being combined. If you look very closely here, you will see the faint outline of a second bird (in fact the same bird a couple of feet further into its flight). 

Unsurprisingly, HDR images take fractionally longer to process than conventional exposures, but compared to the iPhone 4 and 4S, the difference in shot-to-shot time between conventional and HDR capture has been reduced to the point where it's almost unnoticeable. 

Panorama Mode

Various apps are available for the iPhone to create panoramic images, but now the iPhone will let you create panoramas without the need to download any additional software. Panorama mode is new in iOS 6, and is supported by the iPhone 5, the 4S, and the iPhone 4. Essentially, it performs in the same way as the countless 'sweep' or 'easy' panorma modes that you'll find in today's crop of compact cameras, but using its native Camera app the iPhone 5 creates some of the best 'one shot' panoramas that we've ever seen. 

In panorama mode the iPhone must be held in the vertical orientation, and once you press the on-screen shutter button, you simply sweep the phone smoothly from left to right (you can switch to right-left sweep by clicking into the on-screen icon) and a panorama is automatically created.

In Panorama mode, you can create images by panning from left to right (default) or right to left. To change the direction, just touch whichever side of the horizontal bar you want to start from.
During panning, you should try to keep the arrow aliogned with the horizontal blue line. If you don't, or if you pan too quickly, you'll be nagged by an on-screen message. 

Assuming you pan smoothly enough (which can be tricky, as you pivot your body through 240 degrees), the iPhone 5 will reward you with panoramic images that are - literally - almost flawless. Add to this the fact that they resulting files are huge - up to 28 megapixels total resolution - and as sharp at 100% as the phone's conventional still images, and Panorama is perhaps the iPhone 5's single most impressive photographic feature. 

This panorama is almost flawless, and impressively, there is no noticeable distortion around the figures to the right of the scene. This image is as sharp at 100% as a conventional capture from the iPhone 5's 8MP camera. 
It doesn't always get things right though - look at the roof of the distant building in this shot and you'll see some distinct 'stair stepping'. To be fair though, it's barely noticeable even at a moderate magnification. 
HDR capture isn't possible in Panorama mode, so scenes like this, with a wide tonal range, may end up with either burned-out highlights or blocked-out shadows. If the scene you want to capture differs in brightness from right to left, you can change the direction of the panning motion, for a degree of control over the final exposure. 

Digital Zoom

The iPhone 5 doesn't offer optical zoom, but digital zoom is available, and can be controlled using the famililar 'pinch-to-zoom' gesture common to iOS devices (and increasingly, on Apple's desktop and laptop computers). Image quality from digitally zoomed images is very poor compared to full-resolution capture, but is good enough for non-critical use, in a pinch.

No digital zoom - full-resolution capture
Full digital zoom

Post-Capture Editing

If you want to add a little polish to images captured using the iPhone's camera, a small range of post-capture adjustments are available from within the built-in Camera app. A one-touch 'auto enhance' option is useful for giving images an extra 'pop' and a crop tool and red-eye reduction function are on hand for further fine-tuning. Naturally though, if you're interested in post-capture image manipulation, there are hundreds if not thousands of apps available which do a lot more than this. 

The crop tool in the iPhone 5's 'edit' dialog is pretty versatile. You just drag the crop marks where you want them by touch, and press 'crop'. 
If you don't want to do it freehand, you can press 'constrain' and choose from nine set aspect ratio crops. 

As we'd expect from a modern smartphone, images and videos captured by the iPhone 5 can be automatically geotagged, and gelocation information can be read by a wide range of applications (including Apple's iPhoto and Aperture) for display and organization.