Join ePHOTOzine, the friendliest photography community.
Upload photos, chat with photographers, win prizes and much more for free!
The brightest or lightest parts of a photograph.
A light-absorbing dye thats present in the film to prevent reflections and light spread that would create a halo around bright highlights. The dye disappears during processing.
Often quoted on scanner specifications to indicate the maximum tone range that the scanner can capture. A higher figure indicates that the scanner will capture more detail from the highlights to shadows. With flatbed scanners that are being used to scan prints this isn't too important because the tonal range has already been reduced in the printing process. A higher dynamic range is essential on film scanners when scanning transparencies that have a wide tonal range. Specialist films, such as Fuji Velvia, are said to have a range of around 3.7D, so the scanner needs to have at least the same dynamic range to ensure every bit of highlight and shadow detail is captured in one scan. Also see "High Dynamic Range"
A high key image mostly consists of highlights and midtones, is generally bright and even, and delicately toned, often with pastel and/or white shades.
This is technically known as a catadioptric lens and has an unusual construction of mirrors and lens elements. As well as glass elements there are mirrors at the front and rear to fold the light as it enters the lens. Although this results in a body that's a little wider than normal, advantages are: 1. The lens is usually only half the physical length a regular lens of the same focal length would be, and 2. It's much lighter. Disadvantages are: 1. There is no adjustable aperture, so the user is forced to take all of his photos at a permanent aperture setting, usually f8, but sometimes even f11, which means you need plenty of light for taking photos; 2. Practically all mirror lenses use manual focus; 3. Highlights that are out of focus are, in some situations, shown as doughnut shapes (although some actually like this characteristic and consider it an advantage, not a disadvantage).
A box with a diffuser panel that attaches to the front of a flash to give soft even light. Any visible highlights such as catch lights in eyes, reflections in silverware will be neat and square. Bigger ones give more surrounded and even light but absorb more light so are best used with powerful flash heads.
Reciprocity law states that as you increase the intensity of light reaching the film you also need to decrease the speed it reaches the film by the equivalent amount. Most films work quite happily between exposures of 1/2sec and 1/1000sec, but go beyond these extremes with a very low intensity of light and a long exposure or a very high intensity of light and a correspondingly short exposure and the law fails an exposure increase may be required when the shutter speed is beyond these limits. At these extremes the law fails. Compensation is required to adjust for this, but there is no strict rule to correct the error. Most film and paper manufacturers provide technical details on request with a rough guide to exposure adjustments. As a rough guide for an exposure of one second you would increase the speed to two seconds, or open the aperture by one stop. A speed of 10sec would need to be increased to about 50sec or open the aperture up two stops. With black & white film you only have to worry about this exposure correction, but with colour film does not only suffer from exposure problems but also colour casts. A colour film is made up of three individual colour layers, each layer suffers from reciprocity failure at different levels. On an uncorrected film the shadows may have a magenta colour cast but the highlights may suffer from a cyan cast. To correct the cast not only would a longer exposure be needed but also the inclusion of a colour correction filter of a low value, care would have to be taken in choosing the correct filter otherwise an over corrected result may appear.
Invented by Herschel in 1842, Cyanotype produces characteristic Prussian Blue images through the combination of iron salts with potassium ferricyanide. Once coated, the paper can either be left to dry by air in a darkened room or heat dried with a hair dryer. The image is formed by contact printing using the sun, but because the process cannot resolve fine detail, working from a line negative is recommended. Once exposure is complete, wash the print in cold running water for around 30 minutes until all yellow is gone. To brighten the highlights, rinse the print briefly in a dilute chlorine bleach bath, or to lighten specific areas, use a brush and bleach diluted 1:32. As well as paper, Cyanotype prints can be made onto heavy cotton or canvas, but you should avoid exposing finished images to bright light, or they will fade.
High dynamic range (HDR) processing is a technique achieved using software that takes the best tones from several exposures and combines them in one HDR image. The dynamic range is the range of brightness levels in a recorded scene from the darkest shadows to the brightest highlights. This is typically measured in f/stops and has always been a problem for film users shooting on colour transparency film, especially on films such as Fuji Velvia. The dynamic range is around six f/stops from the brightest to darkest points. And while colour negative and black & white film users have always had a few stops to play with, even at a maximum of around nine stops most photographic systems struggle with high contrasts scenes. Several software programs offer the possibility of combining differently exposed shots to one high dynamic range (HDR) image. Also see "High Dynamic Range explained technique".
Used to balance the light of a scene with overly bright highlights. There are physical filters to use in front of a camera lens, and digital filters for use in imaging software. A physical graduated neutral density filter, for instance, has one clear edge and then gradually increases in density towards the other edge. A so-called "hard grad" has a graduated section that reaches the middle of the filter, whereas a "soft grad" has a graduation all from one side to the opposite side. Neutral density graduated filters are the most common types, but there are also coloured versions available - gradient sunset filters, for instance, or tobacco-coloured ones. Physical filters are usually square or rectangular, are used in a filter holder that attaches to an adapter ring, which screws into the front of the camera lens. Sizes depend on the diameter of the front of the lens. Gradient filters can also be applied digitally in photo editing programs. Even when this is not a standard option in the program, often a so-called "plug-in" can be used for use in the program.