Great Landscape Photography Logo Basic Digital Photography III: Taking Control of Exposure By Christine Peppler

In a previous article, lighting was identified as the element which most determines the quality of an image. Working with available light and using internal flash and external light sources were discussed. In addition to the light present, the amount of light on the image sensor, or exposure, is determined by the opening/closing of the aperture and the length of time that the shutter is open. To better understand exposure, this article will discuss aperture, shutter speed, and the concept of "bracketing".

Aperture is essentially the opening that allows light in through the lens. You will see aperture indicated in "f-stops". The smaller f-stops represent larger apertures and therefore more light coming in through the lens. To state it more directly, the larger the aperture the brighter the light obtained. It is also important to realize that aperture also influences some of the focusing within a shot, known as depth of field. Technically, a camera can only focus on one item within a shot with items becoming less in focus the further they are from that point. The depth of field is the range or distance of items that are in focus; thus, an image with a narrow depth of field generally has a smaller area in focus. A wide depth of field is used when wanting detail throughout the shot but a narrow depth of field is desirable when a single object or person is the focus of the image. When using a larger aperture, depth of field is minimized while reducing aperture maximizes it.

Shutter speed is generally understood as the length of time the shutter is open. Slower shutter speeds allow for more light and faster shutter speeds less light. Therefore, a night shot often utilizes a slower shutter speed in addition to a larger aperture to maximize the light coming into the lens. Whenever a slow shutter speed is utilized the risk of camera shake is significantly increased and thus, tripods are often necessary to avoid blurring. Fast shutter speeds, such as 1/250, produce very sharp images and can act to freeze action. A slow shutter speed produces less defined images; images that demonstrate movement by blurring action. Just as with aperture size, the shutter speed selected is not "right" or "wrong", it is merely which will create the type of image wanted.

It is important to understand that when adjusting shutter speed or aperture size it is often necessary to adjust the other to accommodate the resulting change in lighting. For instance, if a faster shutter speed is chosen to freeze action aperture size may need to be increased to obtain adequate lighting for the shot while realizing that there will be a narrower depth of field.

Digital cameras offer the user control over aperture and shutter speed. For the novice, a Fully Automatic Mode in which the camera decides on the shutter speed, aperture, white balance, and focus is most handy. This feature is often sufficient for producing excellent photos but there are limitations. For instance, the camera will not sense when the user is attempting to take a shot which captures faster action. Use of a shutter speed that is too slow in this instance will result in blurring. As described above, it may be advisable to adjust the shutter speed, and possibly the aperture size, for this type of shot.

Many digital cameras also possess a Programmed Mode which allows the user to select the situation that is most appropriate; for instance portrait, sports, or landscape, and the camera makes the decisions from there. As discussed above, adjustments in the shutter speed to allow you to create special effects may be desired but not congruent with what the camera assumes is wanted. Most digital cameras offer a Shutter Priority setting that allows the user to adjust the shutter speed while the camera determines the aperture and other features. In other instances, increased depth of field may be desired and achieved by selecting a smaller aperture. This is possible using the camera’s Aperture Priority setting which will allow aperture alone to be adjusted. The Manual Mode allows both the shutter speed and aperture to be manually controlled. Obviously, this mode allows for the most control of shots but requires a significantly higher level of skill.

A final word about getting the best exposure with a digital camera is about a technique called "bracketing". Bracketing is used when it is difficult to determine the optimum exposure because the lighting varies within the scene. For instance, taking a photograph of a dog sitting in a snow covered field presents challenges based on the extreme contrast and reflection. Bracketing is simply the practice of taking several shots of the same scene with different exposures. Most digital cameras make this very easy to do as they can automatically vary the exposure, taking a shot at the metered setting and others which are under exposed and over exposed. The user then compares the images, selects the best one, and deletes the rest. During the editing process it is even possible to combine the best parts of multiple shots to get the best composite image.

Although automatic settings produce great images, even a novice can adjust shutter speed and aperture to capture action and create special effects within their photographs. Digital cameras make the process easier and less expensive through progressively manual controls and the option of deleting photographs that simply aren't desirable.

Source: EzineArticles.com/?expert=Christine_Peppler

Standards to Assess Thermal Behaviour of Textile Materials and Role of Thermal Manikins

Thermal Comfort of Textile Materials and Its Assessment in dynamic environmental conditions has been discussed in previous two articles. For the correct assessment of the thermal properties, global testing standards are must. These standards are not only useful for thermal assessment but also used for comparison of various products at same platform and are accepted unambiguously. The article discusses various popular standards used for different products in different environmental conditions.
Thermal manikins have proved to be a useful tool in simulation of human body while testing of thermal properties in varied environmental conditions. Some popular thermal manikins have also been discussed in this article.


Thermal Testing Standards


For a comparison a reference point is needed, which can be taken as benchmark to compare the parameters for a given product. Any property or parameter can be evaluated against the standard provided that the standard is developed with consensus and acceptable by all. It may be a characteristic, property or parameter like length or with of any object or colour of any object.


Targeting this objective, same is followed with the testing standards also. Different material's performance can be tested or evaluated differently, but to keep all the results on one platform and for true judgement, the procedure of testing, specifications, equipment used, testing conditions has to be uniform and well defined.


So, if the test has been conducted by following the standard instructions as described in the procedure, the results will not vary with the change of testing location, person, equipment etc.


In the thermal testing of textile materials various test standards are developed and are globally valid.

A Study on Computer Integrated Manufacturing for Textiles

Computer Integrated manufacturing (CIM) uses computers to control the entire production process that involves engineering, production, marketing and all the support functions of a manufacturing enterprise. In the traditional business paradigm, the company is assumed as an island, i.e., an independent and self operating entity. As a company is a part of a broader matrix of business systems composed of customers, suppliers, products and global information, it leads to integration along different axes, namely geographical and functional. Its main objective is streamlining the process of manufacturing and integrating it with all the other business functions such as financing, marketing and accounting. To eliminate the wastage, basic manufacturing functions as well as materials handling and inventory control can be simulated by computers. Nowadays there are many simulation softwares available for different applications where it is not so easy to conduct real time experiments on the real applications. The companies which are centered and vertically integrated cannot easily adapt to the fast requirements of changes in the market. For the companies to be more efficient they need to be global and at the same time local, they should be able to operate in a coordinated as well as synchronized form and should be able to adapt to changing market conditions. The management has to make a decision to make a product based on market opportunities, the company's strength and weakness and its strategic plan based on competitive advantage. Some of the tasks in general that a CIM has to perform includes defining the problem, developing functional, information, network organizational models and finally implementation.

source : http://www.fibre2fashion.com

Application of Digital Textile Printing Technology

Consumer electronics are typically designed with a battery power source and are carried in light limited pockets or bags. The marriage of electronic devices and wearables provides the opportunity to utilize surfaces exposed to the sun to generate energy to power the electronic devices. Photovoltaic flexible thin film converts solar energy into electrical energy. This photovoltaic thin film has a similar thickness to paper and has material properties much like those of camera film. The photovoltaic flexible modules come in various sizes ranging from 2x4in to 8.5x11in sheets. They can be rolled into a three inch diameter without physical damage and continue to function if scratched or punctured. The durability and efficiency of these photovoltaic flexible thin film modules have improved to a point where they are a viable option for incorporation into wearables. Ultimately, these thin film photovoltaic cells can reduce the amount of battery storage engineered into electronic devices and eliminate maintenance related to replacing batteries. Devices such as the Burton Shield iPOD Jacket, Menswear Fall Sensing Shirt, and Shimadzu DataGlass 2/A are examples of smart garments where battery maintenance or battery weight could be reduced by using photovoltaic flexible thin film for charging.


The successful integration of photovoltaic thin film cells into wearables is tightly tied to the consumer concept of fashion. In the consumer market, smart clothing must remain visually attractive and complement or enhance the wearer's appearance; otherwise it will not be commercially successful. In order maximize energy collection, it is necessary to place the photovoltaic film in visibly prominent areas on the wearable. These solar cells are graphically strong and as a result need to be more visually integrated into the garment structure. Digital textile printing enables the designer to incorporate unusual components into a design by printing fabric that matches the pattern of the component. Direct digital textile printing technologies typically employ the use of ink jet printing to allow the user to print designs directly from the computer to fabric. For this paper, digital textile printing technologies refers to a number of integrated software and hardware components that are typically used to create digitally printed fabrics.

These include off-the-shelf software packages (such as Adobe Photoshop and Illustrator), industry specific design and patternmaking software (PAD patternmaking system, Pointcarr), wide-format ink jet printers for direct textile printing (Encad 1500TX, Colorspan Fabrijet), RIP software used for processing the image files into information that is useful for the printer, and other support hardware. The wide variety of wearables to which photovoltaic thin film cells can be applied requires wide variety of fabrics to make these garments which eliminates the possibility of utilizing a large order of fabric. Digital textile printing makes it possible to do small scale production on a variety of fabrics. (Ross, 2005)
By : J. S. Hynek, J. R. Campbell, K. M. Bryden