Focal Length
The focal length of a lens is the distance usually in mm from the lens to the ccd sensor when the lens is focused on an object at infinity.So what is the use of knowing this? Well, If we can understand focal length, it is one more tool to help us take better photographs. Let’s start with what a standard lens is.
Standard Lens
A standard lens gives a view similar to the human eye, about 53 degrees, its focal length is equal to the diagonal size of the sensor. Unfortunately all cameras don’t have the same size sensor. So there can be a lot to remember.For a 35mm film camera the standard lens is 52mm
For DSLRs owned by everyone in the class the standard lens is 35mm
For other more expensive DSLRs the standard lens is 50mm
Bridges and some compacts the standard lens is 8mm or 9mm
Wide Angle Lens
As we reduce the focal length below the standard size, we begin to see more of the scene, and objects appear further away. This is similar to to what happens when we look in a wing mirror fitted to some cars, we see more of the road to the rear and side, but we can be fooled into thinking a car approaching is further away.There is an advantage to fitting more into the frame, for example it can be ideal for landscape shots and can give dramatic views of inside buildings, but there is the disadvantage that the lower we take the focal length, the more distortion will be introduced.
Take care when using a wide angle setting and you’re up close to your subject, you can end up with some strange results. Of course you can always use the distortion for effect.
Photo by Brittney Bush
For DSLRs Wide-angle range is 35mm -and below
Prime lens
You may see the term prime lens used, this refers to a fixed focal length lens, that does not zoom. They usually consist of better quality elements that allow wider apertures to be used. We discussed the advantage of the prime lens that I have as an example.It's a 35mm focal length, but allows 21/2 stops wider aperture than my 18-55 zoom lens.
In practical terms that allows me to use the camera indoors without a flash without worrying about camera shake. It is the difference between being forced to use a shutter speed of 1/20 and 1/120, bearing in mind that I've said all along that any shot below 1/50 can't be hand held.
Telephoto lens
As we increase the focal length, objects begin to appear closer, there is a lessening of the angle of view and a flattening effect takes place.Zoom lenses gives the advantage of flexibility, but at the expense of quality and speed.
While looking for a shot to demonstrate the compression that takes place when using a telephoto lens I found this excellent example series. And later even discovered an accompanying video.
For DSLR Telephoto range is 35mm -and above
Exposure Compensation
I asked you to find the above symbol on a button your cameras. If I'm not mistaken, all of the cameras owned by everyone in the group has such a button.
Set you camera mode to anything except Auto or Manual (try Aperture or Portrait mode) Press the
Exposure Compensation button and you should see a scale appear. 
use the Left / Right buttons or Dial to adjust the pointer as far to the minus side as possible.
Now take a photo. Adjust the scale again back to the centre and take another shot.
Take another photo of the same subject. Again adjust the pointer to the highest setting and take another photo. When you look back at the three shots you have just taken, you will see that the first is considerably darker than the last. The last one will probably be far too bright, but I hope that this will be a valuable tool in adjusting the exposure of your camera in certain situations.
The example I would use is where Joyce complained that when she takes a photo of stained glass windows in a church, the colours look washed out. So by adjusting the exposure compensation down we can regain the saturation in the colours of the window. Remember to turn the flash off in such a situation though.
We also touched again on the subject of portrait photography.
Although we have tried out some portrait photography in the other classrooms in previous weeks,
I haven't really set it as a task for "homework" So I suggested that you try some photographs of people. You don't necessarily have to know the people, in some respects it can be easier if you do not know your subjects that well, but do talk to the person your shooting, ask a few open questions that will give them a chance to tell you something about themselves.
Props are good
If your subject is involved in an activity, holding something or wearing something unusual this can help to tell a story or create questions in the viewer's mind. It's only limited by your imagination.
Focus
To refer back to something that we mentioned a few weeks ago, what is your point of interest? If your photo contains a face, it will be the eyes of the subject that the viewer will look at first. Ensure it is the eyes that are in focus, not the tip of the nose.
It need not contain a face
It does not necessarily need to contain the face of the person, hands, feet and other parts can make interesting subjects.
Watch the background
Apart from the really obvious things like lamposts growing out of your subjects head, at the background for things that distract from the subject. One subtle example is when a horizontal line such as the horizon cuts through the head of the subject.
A recent example I came across was on this website of a prominent solicitor.
Is she wearing a backpack?
See you next week with your people photos.......
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