Week 3

Last week's task

I wanted to encourage you to use obtain a shallow depth of field.  To add a little challenge I suggested using a colour or colours and the number five.  It has probably not been easy to get outside  and take photographs because the weather has been so awful, but you don’t necessarily need to leave the house to take photographs providing there is enough light.  I hope that even just trying to take on the tasks will help you understand the settings of the camera even if you don't

As we learnt last week, aperture is the size of the hole that lets light through to the CCD .  The larger the number of the aperture (f-stop) the smaller the hole and  the less light will pass through.  The shutter speed is the time that the shutter is open to let light through to the CCD.  We normally see numbers such as 60 or 125 etc, but remember they are numbers that appear at the bottom of a fraction such as 1/60 and 1/125.

The third part of the triangle

As with aperture, the larger the shutter speed number, the less light passes through for the exposure.  It should help you to remember that  for aperture and shutter speed the larger the number, the less light is available for the photo.

Both aperture and shutter speed affect exposure, but these are only two points on a triangle which we call the exposure triangle.  The third point is ISO.

ISO

 ISO is like a  joker/ trump  in a game of cards, we can use it to gain an advantage when aperture  and shutter speed try to beat us.  Non SLR cameras may have little or no control over ISO, it may be that the ISO is purely automatic, but understanding that is working behind the scenes  will help you use it to your advantage.  In an ideal world we would keep ISO  on its lowest setting, because as we increase it we begin to see noise in the photograph. Although there are times when you may want to introduce noise for effect.

Evesdropping

To try and explain what is happening, imagine this:
If we place a microphone in the next room to listen to what’s being said through an amplifier and some speakers in this room,  we’ll hear clearly if the person speaking is within a metre or two of the microphone.  If someone speaks who is right across the other side of the room, they’ll sound faint.  So we can turn up the volume on the amplifier in our room and their speech will be louder, but there will be an element of noise amplified also.  Some of this sound will be a hiss or a rumble.  Even if the room is completely quiet there will still be some noise because the amplifier is amplifying noise generated in the circuitry.

This is exactly like  what happens when we increase the ISO of the camera we are turning up the amplification of the CCD, the resulting photo begins to lose detail and we begin to see tiny specs of colour that were not present in our subject and are actually generated inside the camera.

 
Look at these two photos:

The picture at the top was taken at 200 ISO and a 2.5 second shutter speed.
The picture on the bottom was taken at 3200 ISO 0.6666 second shutter speed

You can see  that the lower  has lost the fine detail in the petal and has coloured speckles.  The one above  is well detailed.

All the settings of the camera, aperture, shutter and ISO are related so that we need to balance the settings to get correct exposure.  

Suppose the meter in our camera has  set the camera at 200 ISO, the aperture is 2 and shutter speed is 15.  This shutter speed is slow for a handheld shot, but if we take the shutter speed up by two stops to 60, we’ll be able to get a shot without shake, but we’ve reduced the light coming into the camera  so we can compensate by increasing the ISO by 2 stops to 800. This will give the same exposure.

Or perhaps we wish to catch something moving, we know that the shutter will have to be no less than 500.  When we set our aperture to 5.6 we see the light metre is telling us that the exposure is underexposed by two stops.  we can increase the ISO by two stops to 800 ISO and this will give the correct exposure.

Exif info.

Exif info is data that is stored by the camera with the photo.  It will include  shutter speed, exposure compensation, F number, what metering system was used, if a flash was used, ISO number, date and time the image was taken, whitebalance, auxiliary lenses that were used and resolution.

Camera Simulator

This website has a fantastic simulator with which you can try out your camera settings

 http://camerasim.com/

 Lines Lines Lines

We had a quick look at another compositional  technique, that of lines.  Follow the links below to see the examples that I drew together.



Vertical Lines

Vertical lines create a sense of power and strength, this can be emphasised by framing in a portrait format.  Keep the lines parallel with the sides of the frame.

Horizontal Lines 

Horizontal lines convey a feeling of peace and calm.  It's important to ensure that  horizontal lines remain parallel with the  frame. 

Diagonal Lines 

Diagonal lines can convey a sense of action or make an image more dynamic.  They may grab the attention of the eye and can be seen  in  roads, streams, waves and branches.

Curved Lines 

Curved lines present a sense of grace,  smoothness, and dignity  They don’t create as much action as diagonals and other straight lines. When the eye follows a curvy line, it’s a slower, more relaxed pace. 

Leading Lines 

Leading lines can be curved or straight and are used to draw the viewer’s eye through a photograph. They work well when a point of interest is positioned at the end of the line.

Implied Lines 

Implied lines are not actual lines, but exist because of the way things are arranged in a photograph. We can also imply a line when an object views another object. e.g. in the example photos, the girl taking a photograph we are interested in what she is photographing so our eye is drawn up the line of her view.


This weeks task:

Look out for lines (there are six examples above) and try and incorporate them into some shots.
You can even leave your camera on auto if you want.  But you could try to incorporate using a centred focus. 


See you next week, enjoy the extended weekend. 


Thanks
Mark