Focusing and Focal Length

Focusing

The use of focusing is to allow selected areas of an image to be clearer as it gives it much more detail. (Changing depth of field)

Definition of focus:
- To cause light rays to converge on or towards a central point.
- To focus.
- To render an object or image in clear outline or sharp detail by adjusting vision or on an optical device.

Light

Light travels in straight lines, and the rays diverge from each other. The lens refracts the light rays onto a certain point which becomes the focal point. 

Camera Settings

Auto Focus - Camera automatically focuses and 'locks' on a part of a scene which it (the camera) considers to be the important.

Manual Focus - The photographer physically controls the focus.

1)One Shot AF (Canon)
   Single - Servo AF (Nikon)

This setting is used when taking a photo of still life, or when there is close to no movement. Once the auto focus has achieved focus, the setting locks.

2) Al Servo

This setting tracks focus on a moving object. Whether the object is moving closer or further from the camera, it stays in sharp focus. 

Focal LengthFocal length is measured in mm, it is a measurement of the distance that the light rays converge to form the image. The focal length tells us the angle of view (how much of an area is in view). The longer the focal length, the lower the angle of view and the higher the magnification of elements (300 mm) . The shorter the focal length, the wider of view and the lower the magnification (18 mm). 

Lenses

- Normal / standard lenses are 50 mm which is the equivalent to the human eye.

Zoom Lens - Variable focal length

Prime Lens - Set focal length

Collagraph Printing

Making the base

Collagraphed printing includes gluing textured materials to a cardboard base, then adding ink to print final images. For this workshop we used Intaglio printing rather than Relief printing. When creating the plate, the height variation should be minimal so that the print works better.

The equipment used could include: Board, PVA, Glue, Moulding Paste , Carborundum, Sand, Glue Gun , Textured materials ,Textured wallpaper, Card/Paper Shellac


Printing
Before printing, the plates need to be sealed with varnish.To create the prints of the textured boards, ink needs to be added. First cover the working area with newspaper then using a toothbrush, add caligo relief ink over the cardboard base and make sure to get full coverage. Then using scrim to remove a chosen amount, depending on how dark the section to be printed needs to be. The thicker the layers, the darker the print will be.

Once the chosen amount of ink is applied, it needs to be printed using the press. Using a damp piece of watercolour paper and lay it over the cardboard base, then put it through the press. Multiple prints will be needed to find the best outcome.

Health and Safety:
- Wear gloves and an apron whilst using the inks
- Be cautious when using the press
- Clean up work space when finished

Artists work:

Ariel View Print Of Exeter / Lynn Bailey

Hedgerow / Lynn Bailey

Laurie Rudling

Somerset Levels / Sue Lowe

Kilve Beach / Sue Lowe