HDR

HDR seems to be a contentious topic; some people really like it, others hate it with a passion. For those who hate it, their reasoning usually comes down to the existence of a seemingly endless amount of really horribly edited photos whose only upside is that they look extremely wacky (see below). However, done well, HDR can be an very useful tool.
Note: click on any image to make it big

This, in my opinion, just ruins the photograph

A far more natural look

(For those who don't know what HDR is, the next section of this post will explain it. If you're already familiar with it, you can skip this bit)

HDR stands for High Dynamic Range. If you don't know what dynamic range is, there's a very good explanation here.

Let's say I want to take a picture of this church. It's a nice shot, but I've lost most of the detail in the clouds, and I'd really like to have the sky properly exposed.

So I dial in some negative exposure compensation, and take a new photo. The clouds look fantastic now, but the image as a whole is way too dark and I can't see the church any more.

This is where HDR comes in. It lets you have your cake and eat it. (Where the cake is the clouds and eating it is being able to see the church... I probably could have thought of a better expression here.)
The final result is this. Nice looking church, great dramatic sky. Fantastic.

You may notice the church looks different to the first image, and the clouds different to the second image. This is because the final picture is a merge of 5, rather than 2, images.

So how do you go about taking an HDR? The first thing you need is (usually) 3 or more images at different, preferably equally spaced, exposures. The easiest way to do this is to take advantage of your camera's exposure bracketing function. Go to your camera's quick menu, and access the exposure compensation settings. On a canon camera, turning the top dial here will turn on exposure bracketing (the one little line will turn into several)

Press the set button to save the setting and you're good to go. Now your camera will cycle between taking photos at 0, +1 and -1 exposure compensation. The more you turn the dial, the more widely spaced your exposures will be (eg ±2, ±3 etc). Using the rear wheel or directional buttons (depending on your camera) you can also move the middle point. This is useful if you want, say, -2, -1 and 0 instead of -1, 0, +1.

If you want to take your bracketed photos handheld the best thing to do is set up the bracketing, put your camera into burst mode and simply hold the shutter button. It should take one set of 3/5/7 photos (depending on what you've set it to) and then stop until you release and press again. At least, it does on most cameras. (Side note: Almost all cameras will let you do sets of 3 bracketed images, and more expensive ones give you the option for 5/7/9 etc. 3 is almost always enough though, so don't worry. If you want more than 3 and you're shooting Canon, then magic lantern will help you out)

Assuming you now have your bracketed images, you'll now want to merge them into a single HDR image. There are many programs allowing you to do this, but by far the most popular (and the one I used for the images in this post) is Photomatix Pro. Unfortunately, it's $99. That said, it is excellent. If you want a free alternative, after a quick bit of google-ing and playing around, I'd recommend Luminance HDR. It's not particularly user friendly, but after a little playing around I ended up with this, using the same source images as the one above. (It may appear to have a little less "pop", but that's just because I didn't spend as much time on it in photoshop. More on that in a bit).

You can open RAW images (and of course JPEGs) directly with both Photomatix and Luminance. If you use Lightroom you can export directly to Photomatix, but not Luminance.

Photomatix
Upon importing your images into photomatix, you'll be given some options, which are fairly self-explanatory. Upon hitting "ok" the software will do some analyzing and present you with an image under the default preset (the more things you ticked, the longer it will take). You now have an HDR image you can edit. For the most normal look I'd recommend setting the process (in the top right) to "Tone Mapping" and the method to "Details Enhancer". Next play around with the sliders on the left until you get something you like - there's a handy box at the bottom which tells you what each one does. (The "more" and "advanced" options rarely need touching). I've created a preset which I find to be a useful starting point for most of my HDRs, which if you would like to use is available for download here. It works best on wide shots of buildings, as this is what I tend to use HDR for most. If you start doing a lot of HDRs it'll be worth your while creating a preset for each type of photo you take (eg architecture, lake, city etc). If you simply want a bunch to play around with, a quick google will yeild plenty for download. To use them in Photomatix, simply grab the presets drop-down menu right next to the "process" button and hit "load preset".
Once you're done with your adjustments hit "process". Photomatix will then apply the adjustments to your photo and give you a final image. From here I like to hit "save as", save a 16-bit .tif image and continue editing in photoshop. If you're happy with your image, however, you can simply save a JPEG and you're done.

Luminance
Click "new HDR image" and import your photos. Much as with photomatix, you'll be given the option for auto alignment and auto-crop. Luminance takes much longer than Photomatix to align images, in my experience, but it does work rather well. Next it'll give you an "editing tools" screen which allows you to check they have been aligned properly, and also has anti-ghosting options which unfortunately I haven't had enough time to figure out (again, I use Photomatix and have spent very little time with Luminace for posting purposes. For now just click next...)
If you want a natural look with Luminance, the way I did it was by using "profile 5" when importing and then using the Mantuik '06 operator with the Detail Factor at 1. (I've checked with a few other images and it seems to work fairly consistently. (I'm sure there are far better tutorials on luminance out there, so if you want to use it I would recommend above all else doing some google-ing to find somebody who, unlike me, knows what they're doing :p)

To round off, here's a few more of the HDRs I've taken recently

And finally, a beautiful shot by the wonderful Josie Segar:

As always, send any questions to benji@the-photography-blog.com and I'll be happy to help.