Exercise 1.8 Zone System in practice

The aim of this exercise is to demonstrate awareness of the Zone System relating to High Dynamic Range ('HDR') imaging and to adjust for light in differing light conditions.

The notes preceding the exercise point out that cameras do not possess the dynamic range of the human eye (this is The Holy Grail of camera developers) and that this is a particular issue for landscape photography as images frequently suffer form either or both of a foreground that us too dark or a sky that is burnt out.

There are several ways to overcome this:

•  Exposure bracketing in the camera - take several images with differing exposures and merge them. My Canon 7d Mark II offers this as an 'in camera' HDR option and is used in this exercise; 
• Take the images for exposure bracketing into post processing ('PP') software such as Photomatix or within Adobe and use the software to tweak the output. I use both of these softwares in this exercise (but using the Adobe Camera Raw HDR option rather than Photoshop's HDR, which I view as unsatisfactory);
• Improve the dynamic range of a single image by using PP. In this exercise, I take the middle image of three taken at a range of exposures into Topaz Adjust and apply a preset (Light or Medium Pop Grunge). An alternative is to use shadows/highlights available in Photoshop and a range of other softwares to boost the former and reduce the latter.

The three scenes are landscapes taken near the coast: second Severn Crossing; cliffs on West Somerset Coast Path; and Penarth pier.  In each case, the HDR function has been used in Auto mode on the Canon. I find Auto works fine usually, adjusting the range of stops without  having to work out by trial and error and risk ending with a plethora of images to review. I also only ever take three images for HDR merging; that number seems to work perfectly well with some additional PP and, in any case, is the most that practically can be taken handheld (I take very few images on a tripod due to practical difficulty of carrying one on lon distances) without ghosting becoming a problem.

Each scene has seven images, successively: 

• the under/over/middle exposures as taken in the camera (the originals were RAW images but saved as JPEG for this exercise); 
• the HDR as merged in camera (called 'Canon');
• HDR as merged using Adobe Camera Raw (called 'Adobe');
• HDR as merged using Photomatix (called 'Photomatix');
• Single image HDR using Topaz Adjust HDR on the middle exposure only.

The results are on a Flickr collection accessed below. It is important to note that no additional PP has been applied: it is usual to apply more than just HDR processing to images but for this exercise it seemed best to have images that were produced using consistent PP.

The dynamic range of the three images varied; the range for the cliff scene being much less because there was less sky in the image, and that sky is darker. That is one of the benefits of using an Auto setting in camera. 

The results are much less variable than might be expected - none of the images are acceptable in HDR form shown without further PP to boost clarity, sharpness, tone and contrast - but demonstrate how technology can be used to obtain a better image with a fuller range of exposures. The single image using Topaz Adjust works well for the Severn bridge and Penarth pier shots, perhaps emphasising how sophisticated PP software has become.