• HDR photography - Beginners Guide

    HDR (High Dynamic Range) photography is one of these concepts that can seem very intimidating for a lot of novices but the reality is far from the truth. Itís a relatively simple concept and itís actually quite easy to learn. Mastering HDR is a completely different problem, but thatís obviously applies to all areas of photography. To look at some examples of HDR, do a Google image search for HDR and you'll see that some of the results of what can be achieved are quite astounding.

    Overview

    Most users may or may not be aware that HDR is now incorporated into even the more simple of photographic tools. If you look at the camera options in your iPhone, you'll find HDR is one of the options you can use. All modern day DSLR's should have this facility available although in most cases, itís referred to as bracketing, rather than HDR. In the past, photographers used bracketing where lighting was particularly challenging so the photographer opted to take multiple exposures to try get the best results. There are a multitude of types of bracketing (white balance, focus etc.) but they aren't relevant in this case. Believe it or not, but combining multiple exposures actually dates back to the 1850's.

    Without going into the complex logic and explanations of dynamic range (which are best explained on other sites that can cover this far better than I can), in its simple form, HDR photography is a simple concept designed to cater for photographic situations where uneven light makes it difficult to achieve a good photo. This could be due to any number of reasons but the example I've shown below is a relative simple one I created from a sunset outside my apartment. In principle, the problem with this type of photo with a single exposure, you either expose for the sky and the land looks too dark, or you expose for the land and the sky is blown out. These days you can use some post processing to improve the results with a single exposure, like lightening the shadows but the problem with this is get heavy noise in these areas. When people look at a scene, the problem often isn't obviously because the human eye us actually incredibly complex. Unfortunately, cameras aren't as smart as your eye so they can't do both at the same time and this is where HDR comes from.

    To help overcome this, we use camera bracketing. What camera bracketing allows us to do is to take photos over a spread of settings and then use a software tool to combine them and get the best possible outcome. This means we take some photos to expose for the sky and some to expose for the ground and then combine the best parts of each photo. With HDR, we can combine any number of photos but this is largely dependent on the camera unless you use manual mode so it could involve combining 3,5,7 or 9 photos, each with slightly under or over exposed settings.

    If this doesn't make sense yet, lets look at the examples I created:

    This is a typical photo you would encounter for this type of lighting if we exposed evenly. I.e. taking into account the sky and the ground. Unfortunately, as you can see, the ground looks too dark and the sky looks too light so we have a problem.



    If we exposed for the sky, this is the kind of photo we would achieve. Again, now the sky is nice (a little overexposed still but we'll ignore that) but the ground is way too dark. We could lift the shadows but this is not an ideal solution because we get a lot of noise coming through.



    If we exposed for the ground, this is the kind of photo we would achieve. Now we have the ground looking nice but the sky is way overexposed.



    To counter this problem, we now take a spread over the entire range (I've used 5 photos) to try getting the best possible combination of lighting conditions. The wider the spread, the better the outcome. You can see from this spread we have a variety of different conditions now, some over exposed and some underexposed.



    Now, one of the reasons we use bracketing is that the camera understands to keep the settings exactly the same and only adjust some of the settings to cater for the increase or decrease in exposure. Its important to use Aperture Priority mode as a starting point to keep the aperture consistent. because any changes to the aperture affect what is in and out of focus on the camera. We then use a tool to combine them, often adding different affects depending on the tool and the outcome can look something like this:



    Taking Photos using Bracketing

    Setting up the camera for taking photos using bracketing is largely depending on the camera. On the iPhone you can find a menu option that gives you access to HDR although the iPhone is unlikely to be the HDR tool of choice.

    For DSLR's, its best to check the manual and then select the bracketing option based on the individual camera. Bracketing on a camera generally gives you two options although some of the cameras may give you more:



    1. Number of shots

    This is where you select the number of photos you would like to take. You can select 2,3,5,7 or 9. The reason 2 is an option is more related to other requirements for photography where a photographer may choose to take 2 photos, one normal and the other slightly over or under exposed as a backup for a particular scenario but the 3,5,7 and 9 are normally the options you'd select here.

    2. The size of the gap (exposure increment)

    This is normally referred to as "Exposure Increment". What it means is how big do you want the lighting gap to be between each shot. 0.3 (a third of a stop) indicates a small variance whereas 1.0 (one full stop) indicates a big variance. To put this into perspective, one full stop indicates half or double the shutter speed with all the other setting being the same. In the examples I've provided, itís adjusted the shutter from 1/13, 1/25, 1/50, 1/100, 1/200. I would be careful. Sometimes auto-ISO can affect your exposure increment.

    Software Tools to combine photos

    There are a number of software tools available to combine your HDR photos. You can use Photoshop itself, Photoshop plugins, Aperture plugins or stand alone products if you don't have Aperture or Photoshop. A number of these packages have presets that you can use for a particular type of look and feel but obviously you have the flexibility to manipulate these photos manually.

    I'll cover of these tools briefly along with some samples of the preconfigured scenarios that are provided.

    Photoshop

    If you're in Photoshop, you should be able to find it under the menu path File > Automate > Merge to HDR or File > Automate > Merge to HDR Pro

    It'll give you the option to select the photos you want to combine and then start the process of combining them. Like most HDR tools, it comes with a number of options to adjust the photo for a particular look and feel or you can use one of their presets which include Photorealistic, Saturated, etc.



    HDR Efex Pro


    HDR Efex Pro is an HDR tool from Nik Software who make a number of really great plugins for Aperture although they do offer versions of the software for Photoshop and Lightroom. My personal preference is Aperture as I use this as my library management tool but obviously this comes down to personal preference.



    Photomatix HDR


    Photomatix HDR is another HDR tool although Photomatix has the advantage of also being a stand alone product so if you're not using Aperture, Photoshop or Lightroom, this may be one to consider. Photomatix also provide plugins for Aperture, Photoshop and Lightroom.



    Which software product should I pick?

    Realistically, all three have good products. For pure HDR, Photomatix and HDR Efex are the pick of the three because they are specialist HDR products but in selecting between Photomatix and HDR Efex, its probably best to download trials and try them yourself. They both have pros and cons and in most cases, you'll find you prefer one over the other for personal reasons.

    There are a number of more detailed comparisons and the purpose of this article is not to provide a detailed analysis of either product. My suggestion would be to do a search at the time of deciding because both products are good and the better one is likely to be the one with the most recently released version.

    Tripods

    One of the most important parts of doing bracketing is having a decent tripod. The reason for this is you need to have 3-9 photos which are identical in terms of photo framing. To try achieve this by hand holding a camera is pretty tough, but it is possible so don't despair if you don't have one. That said, even a cheap tripod is better than nothing if you want to experiment and even a tripod replacement can do a better job than hand holding the camera so these options are always available.

    Conclusion

    Hopefully this introduction has been enough to ensure that some of the novices out there will consider using this technique. Whilst you may not use it often, there are occasions where HDR can really shine and having this trick in your arsenal can be really helpful.

    I'd like to thank Nik Software and HDRSoft for supplying review copies of the software for this article. To get trials of the software used for processing HDR files, you can download a trial copy for HDREfex Pro or Phototomatix HDR. Both Photomatix and HDR Efex Pro retail at US$99.

    Experimentation

    If you want to play around with HDR, I've provided samples of the images used in this article. You can download them here
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