EXPOSURE

It is very easy to believe that the two dimensional images when you watch a television programme or film are believable reproduction of the original scene. There are many manipulated productions on television that have the audience believing that they are watching an honest representation of what was filmed at the time.

It is an important technique to manipulate exposure to control the look of a shot. Video cameras are not as adaptable as human perception; subtle tonal differences can be easily detected by the eye, the brain automatically adjusting and interpreting the information without us having to consciously think about it.

The signal on the television is designed to handle no more than approximately 40:1. However, there is another difference between viewing a television image and observing a subject; a television image is attempting to tell a story and also creating an atmosphere or emotion designed to manipulate the response of the viewer(s). On the other hand, human perception is conditioned by psychological factors which sometimes delude us into often seeing what we expect to see as opposed to what we really are seeing. For this process, exposure plays a crucial part of camerawork. A lot of thought needs to go into what is required including; tones recoded, use of lighting, staging, stop number etc. all to affect the observer and how he relates to the image(s) shown, this is important and a key production tool. Factors which can affect decisions on exposure are:
1. Contrast range of the recording medium and viewing conditions.
2. Choice of peak white and the details in the shadows is to be preserved.
3. Subject priority – the principal subject in the frame.
4. The electronic methods of controlling contrast range and which one are used.
5. The lighting techniques applied in controlling the contrast.
6. The staging directions – where someone is placed affects the contrast range.

EXPOSURE OVERVIEW
- An overall system gamma of around 1.08 is required for an accurate conversion of a range of tonal contrast going from light into an electrical signal and back again.
- The use of additional lamps or graduated filters or compression of highlights will be required when necessary when the scene contrast range can’t be accommodated by the five-stop handling ability of the camera.
- The camera man will decide the choice of compressed tones by altering the iris by either the use of highlight control or the transfer of the camera’s characteristics.
- Automatic exposure cannot judge what may be the important subject in the frame. It gives exposure for the average light levels and some the weighting to centre frame and continuously adjusts to any change in the light level in the frame.
- It achieves exposure by a combination of F number, shutter speed and gain setting. The noise will increase with the increasing gain and the shutter speed will be dependent on the subject content. The F numbers control the depth of field and are based on shot content.

DEPTH OF FIELD
When a lens aperture is chosen to shoot in daylight, it will be dependent on the choice of the required exposure. The depth of field is proportional to the F number. Other factors may affect exposure if the in focus zone is a significant consideration in the shot composition. Several things may need to be adjusted such as:

1. Neutral density filters.
2. Altering gain which includes the use of negative gain.
3. Altering the shutter speed.
4. Adding or removing light sources.

More often than not, there are opportunities to achieve required aperture when shooting interior shots by the choice of lighting treatment, however, daylight is at many times more powerful than portable lighting kits. Some of the time, the depth of field on shots that are similar in size will need to be intercut in order to be matched. The higher lens specification that is required for digital cameras usually ensures that the slight loss of resolution is not noticeable even when you are working wide open, however the lens sharpness may decrease while the lens opens up. Definition problems may occur with the auto-focus and anti-shake devices, even more when you are attempting to extend the zoom range electronic magnification.

www.candyjarfilms.co.uk

HAPTIC TECHNOLOGY - THE FUTURE OF COMPUTER NAVIGATION?

Whilst their hands are full with the upcoming release of the Xbox ONE, Microsoft have released information about their latest 3D navigation technology, named 'Haptic'.

The idea is based around a flat panel LCD screen with force sensors that ‘push back’ at any contact such as your finger. The concept, that has come from the scientists from Microsoft’s Natural Interaction Research Group is that this panel will respond in different amounts of force, potentially allowing your brain to recognise the range in density between one material and another.

With enough force, the screen will replicate solidity.

What follows, is the wide range of ways in which it can be used. To many, their first thought might be entertainment – or more specifically, video games. The ‘3D touchscreen’ idea lends an impressive sense of freedom and interaction, essentially an even more advanced version of the current generation’s use of motion control. However, Microsoft themselves have theorised that the technology could be utilised in the field of medicine as well.

Specifically, doctors could use Haptic technology to locate anomalies within muscle tissue such as tumours - the further the user’s hand pushes into the panel, the deeper into the muscle the display will show.

Before this technology becomes available to the public however, flaws must inevitably be corrected. Challenges such as replicating more complicated surfaces such as rough stone or even muscle tissue would pose great difficulty for even the most advanced of hardware.

Just how easy would it be to replicate these materials?

Yet with these developments and improvements, there is also plenty of room for potential. If at this stage, the technology is a basic idea, consider the possibilities when it will no doubt become fully accessible to the public. The question is...when?

www.candyjarfilms.co.uk

VIDEO PRODUCTION TECHNIQUES: FOCUS

As an integral element to film and video, focusing determines the sharpness of an object or image by adjusting the lens, providing an acceptable visual perspective known as the depth of field. The art of focus lies in knowing what part of the frame needs it most, and the avoidance of over-shooting. For example, interviews or ‘talking heads’ within television are an excellent example, with the eyes of the given subject being an important point for the viewer’s attention to be drawn to. However, much of this will lose meaning if you don’t learn the behaviour of your camera itself and the way it captures distance, sharpness, movement and zoom in relation to the focal plane (the area in which the eye or camera draws attention to). Without any of these elements, the image within the frame will appear ‘flat’, with no sense of immersion or depth.

Depth of field: Notice how the subject is sharp, while the background is soft

To avoid this, and to gain an understanding of how integral focus can be to your shot, practice is a crucial element. For instance, even with the most professional equipment, manual focus is a critical skill with any level of video production. Here are a few ideas to experiment with and try out:

Pulling Focus:

Within the frame, attention is drawn towards the subject with the sharpest focus. This attention can be changed through the use of focus pulling. For instance, a foreground subject (such as a person) can move away from the frame, with focus instantly thrown back to the background, containing a second subject.

Differential Focus:

By using a deliberately narrow depth of field, emphasis on a principal subject can be increased. This is down to the contrast between the sharp focus of the principal subject, and the heavily out of focus background (and sometimes a foreground subject is used as well which is also out of focus).

Zoom lens and focus:

Provided the back focus has been correctly adjusted, this is designed to ensure the focal plane is maintained throughout its range. By zooming in without manual focus, images can lose focus and become distorted.

By becoming familiar with these ideas, you can be more artistic and manipulative about what you want the viewer’s attention to be drawn to. As an important but often overlooked aspect to filming, these techniques are most often mastered through practice and experimenting. 

To find out more about the different techniques with focus, check out these links:

www.mediacollege.com/video/camera/focus/

en.wikipedia.org/wiki/Cardinal_point_(optics)

www.techradar.com/news/photography-video-capture/cameras/how-to-use-your-new-digital-camera-1049684/8

CANDY JAR FILMS