Depth of field - Aperture Priority
I think my first revelation once I really started getting in to photography was that while using the automatic function on a camera often produces images from good to quite spectacular, it can be hit and miss. The camera can't anticipate what you really hope to capture. It makes a calculated guess when you focus on the subject. When I bought my first camera above the point and shoot variety I developed a desire to start using the functions on those wheels and buttons on top of and on the back and front of the camera body, after all they weren't just on the camera to get in the way of your fingers.
I did a lot of self learning, often researching on-line or through photography magazines. The two functions on the camera dial that initially interested me were aperture priority 'A' and shutter speed 'S'. On some camera brands these can be marked as Av (aperture value) and Tv (time value). Knowing what I now know, these are key functions in getting a really good photo. In fact, while I do use manual setting 'M' (subject to a future discussion) my go to is frequently aperture priority 'A' and then shutter speed 'S'. For those seeking to learn more, the effects of these two functions which work in tandem with each other in creating the image are quite pronounced. In this post I will excuse the pun, 'focus' on Aperture priority which influences depth of field sharpness and I will discuss 'S' or 'Tv' (shutter priority) next time.
Depth of field relates to sharpness of the image captured from foreground to the far distance/background. Typical ranges of apertures used in photography are from about f/2.8 to f/22 or f/2 to f/16, covering 6 stops. Ranges and f/stop divisions vary for different lenses. The larger the aperture f/stop number the greater the depth of field. The lower the aperture f/stop number the lower the depth of field meaning objects in the foreground are sharp while the background is increasingly blurred. Changing the aperture changes the amount of light transmission through the camera lens. A reliable aperture setting for clear sharpness from near to distant is f/11.
For a good guide to aperture have a look at A Beginners Guide to Aperture and Depth of Field in Photography Talk.
I took the photo below in my garden with a low aperture setting of f/2 and the camera automatically set 1/160th sec as the shutter speed to produce a correctly exposed photo.
The very low aperture value of f/2 has completed blurred out the foliage in the background making the greenstone pendant the clear subject of the photo.
In the image below I used f/13. Notice the clarity from the rock in the foreground the camera was sitting on to the horizon. The atmosphere was hazy and with greater atmospheric clarity the sharpness from foreground to background would have been even more noticeable.
Most lenses have an aperture 'sweet spot' where the sharpest image is obtained. I find apertures between around f/5.6 to f/11 give the best results for getting sharpness from front to back of the image. I have seen f/11 described as the 'who cares' default setting for landscapes as it generally provides good depth of field clarity, which is what you want in a landscape photo.
Next time I will discuss shutter speed priority; 'S' or 'Tv' on most cameras.
Such are the days of autumn
I took this photo yesterday as autumn starts to paint the landscape in vibrant colour. In this part of New Zealand the warmer climate means we don't get the really rich tones to the extent they are seen in the south but there are pockets of autumn beauty to be found, and in this area its hard to surpass the very beautiful McLaren Falls Park.
ANZAC Day 25th April
Today we celebrate for the 100th year, a national day of remembrance in New Zealand and Australia that "broadly commemorates all Australians and New Zealanders who served and died in all wars, conflicts, and peacekeeping operations and the contribution and suffering of all who served".
My grandfather Arthur Gordon Taylor served in Europe in the Great War 1914-1918. He was a specialist machine gunner with the 25th Reinforcements, New Zealand Expeditionary Force, who set sail for Plymouth in Devon, England on the 'Turakina' in 1917. He was one of the lucky ones to return home but he never escaped the psychological toll of the war, having spells in psychiatric care. He was a a quiet man who never really spoke about the war but was clearly mentally tormented by his experiences. I am fortunate to hold his service certificate, medals and photographs in trust to pass to future generations.
The Turakina (below) was designed for passenger and cargo services between Great Britain and New Zealand and was requisitioned as a troop carrier in WW1. It was this ship that carried my grandfather to Europe. Turakina was torpedoed and sunk by a German submarine on 13th August 1917 en route from London to New York.
The Klink : a souvenir of the voyage of S.S. Turakina (H.M.N.Z.T. 84) April to July, 1917; and a history of the doings of the Left Wing of the 25th Reinforcements N.Z.E.F. on their way to the Front.
Hope you enjoyed this mix of photography info and family history. If you'd like to be alerted to updates by email, just contact me. email@example.com