Focus and Bokeh

While exercising the dogs in the back garden this morning I amused myself by taking a few photographs. Once able to view the results on the computer I found the topic to discuss here - focus and bokeh. It does seem a bit strange to give "out of focus" a special name, but that is exactly what "Bokeh" is. A few people have adopted the name to mean circles of colours created by shooting a near subject and getting Christmas lights dramatically out of focus, however Bokeh covers much more than just that. one of my shots from this morning almost gives those circles of light. The shot was taken with glimpses of sky showing through leaves that were behind my subject.

F4.5       1/200sec     ISO 640     44mm

When taking any photograph you need to "simplify" it. Always try to determine what it is that you are wanting to show. "What is it that caught my eye?" When you look through the viewfinder or at the LCD screen you can tell that the camera does not necessarily see what YOU see! Then it is time to do a little tweaking of the settings so that it really is you that controls the image. With a point and shoot camera there is not much in the way of tweaking that can be done (without getting hopelessly confused) but by altering the pattern of focus to "Spot" focus and getting closer to the subject, you will be surprised at the difference you can make to your shots. (There is usually a menu setting to change the focus pattern)

With an SLR camera set the controls to Aperture priority and a low "F" number (5.6 or less). Get reasonably close to your small subject and use the lens at the full zoom - Since I was using the 18-55 mm lens I zoomed in. The viewfinder reveals the magic of the wide aperture, throwing the background completely out of focus.
The morning was quite dull so to allow the camera to enable a faster shutter speed I increased the ISO - but being aware of the many writings about taking care not to get "Noise" into the image I (so far) have not taken the ISO past the 800 mark. Today I used 640 and it seemed to allow me to take hand held shots with clarity. (Click on the pictures to see them larger).
This next image is of the unusual flowering tree the "Firewheel" the flowers grow inside the canopy and can only be seen by peering into the branches.

F/5.6        1/80sec     ISO 640    55mm

Again I have focused on the flowers and tried to throw the rest of the tree out of focus while still keeping an idea of where the flowers are growing. If you take note of the F stop that has been used, (F/5.6) it is a little bit narrow than for the previous picture (F/4.5) - this allows a greater depth of focus - the bigger the F stop number the bigger the range of focus. Because I am using Aperture priority, the camera decides the shutter speed. It is only just fast enough for hand held shots - I have a very shaky hand and would need a tripod for any speed slower than this. A tripod in  this situation (aiming up into the tree) would have been very difficult to set up - especially since I needed to be close to the flowers which were quite a reach!
My next picture is of a head of not yet open flowers on the Golden Curl  Tree, this time the bokeh is not in circles of light but just of blurred colour.

F/5.6    1/50    ISO 640    1.12m

The blurred background is still called "Bokeh" and yet you can make out the big branched leaves of a tropical plant and some smaller almost heart shaped leaves behind them. The reason the background leaves are easier to define is because I could not get close to this branch to get the framing I wanted. This time I am over a metre away from the main subject. (I just proved myself wrong about the shaky hand - check out the shutter speed!)
My final shot also shows off some lovely "Bokeh". The Grevillea has an unusual flower that is a joy to photograph! There are many variations of the plant with lots of different colours to the flowers as well as flower size and shape but all have these curving long tubular florets like the antennae on a butterfly.

F/5.6    1/125sec    ISO 640     55mm

This time the camera is pointed down to include the lawn beneath the flower and since it is close to the flower and the lawn some meter and half away, the flower is the main feature of the image and the bokeh provides the background canvas. Since this shot was taken out where it was brighter the shutter speed is quite a lot faster than in the previous image where I was under the dark shade of trees. The Aperture setting is the same as in the last picture - I set that - the shutter speed is determined by the computer in the camera.
Sometimes it is not possible to use the autofocus - especially when the subject is very thin, such as when taking the flower head of a stalk of grass. Then it is necessary to switch to manual focus.
AJ

Aperture - one explanation

I would like to show you why more and more people are moving away from a point and shoot camera and getting themselves a digital SLR. If you look at the prices of cameras you will see that a good brand SLR can be cheaper than a point and shoot. I am not writing to argue the "pro and cons" of the different types of cameras, there are plenty of articles to give you those. What I would like to show, along with three photos I have just taken, is something that can be done with an SLR with no complicated pressing of menu buttons.
Just as on a point and shoot camera there is a wheel on the top of all SLR cameras that gives different scene modes. (I have not found or heard of anyone with an SLR who ever used these scene modes!) This same wheel has three extra things written on it.
M - which means Manual mode - this takes the most skill to use and get good results.
A or Av (Nikon =A, Canon =Av) - the aperture can be set manually while the shutter speed is automatically adjusted by the camera.
S or Tv (Nikon =S, Canon = Tv) Here the shutter speed can be set manually and the camera takes care of the aperture setting.
The most usual setting SLR users employ (those that aren't using full "Auto"!) is A or Av, the aperture control. It is this setting I will show the reasons why.

With the camera set on A (I am using a Nikon camera - the D90 model) so I am in control of the aperture settings, I have chosen to set the camera at f/1.8 (Using a 50mm prime lens). The smaller the F number the narrower the field of focus. Its so easy to remember that connection!
Even without clicking on the picture to see it larger, you can see that the place mat under the pen is not in focus either nearer to the camera nor behind the pen. The depth of field is just enough to show the pen. If I used this setting to take a picture of a dog's looking at me, the nose would be in sharp focus but the eyes would be out of focus. Small F number, small range of focus.

This time the aperture setting was changed to f/9 and you can clearly see the flower pattern on the place mat in front of the pen and about the same distance behind the pen. The shutter speed has changed but I am not telling you what it is - the camera took care of adjusting the shutter speed to make sure the amount of light and shade was to the camera's liking. This choice of aperture setting is often used for such things as shooting wild-life and getting the animal in focus and the background blurred.

The aperture on this occasion has been set to f/22 and because the camera slowed the shutter speed to almost one second, I had to use my mini tripod to keep the camera still. The high f number has given a very wide depth of field and the entire place mat is in sharp detail.  (Large F number, large depth of field.)
I hope that my explanation has been simple enough for you to follow.
Really, the camera operator is still using the camera's automatic settings - the focus is set automatically and the shutter speed is set automatically - and yet there is far more control (with no real brain work needed) to get the sort of shot that is required.
The people who want "everything in focus" will always use full automatic settings and are really using the SLR as a "point and shoot" (but will get better results) however the more adventurous photographer can experiment with depth of field by choosing to use the Aperture Priority mode.
AJ