Photographic Glossary-S

Safelight
A special darkroom lamp whose light is of colour and intensity that will not affect light-sensitive photographic material. Not all such material can be handled under a safelight, and some required a type designed specifically for them. An enclosed darkroom lamp fitted with a filter to screen out light rays to which film and paper are sensitive. Light source consisting of housing, lamp and screen of a colour that will not affect the photographic material in use. Safelight screens are available in various colours and sizes for specific applications.

Safety film
A photographic film whose base is fire-resistant or slow burning. At the present time, the terms "safety film" are synonymous.

Sample
In imaging, to gather the value of a colour. to select an image colour to be used in a drawing or painting tool.

Sandwiching
Combining two or more negatives or slides to produce a composite image either on one sheet of printing paper or on a slide-projection screen.

Saturation levels
Light intensity that exceeds the maximum level designed for a CCD.

Saturation
An attribute of perceived color, or the percentage of hue in a color. Saturated colors are called vivid, strong, or deep. Desaturated colors are called dull, weak, or washed out. The vividness or purity of a colour; the less gray a colour contains, the more saturated it is.

Scale
Focusing method consisting of set of marks to indicate distances at which a lens is focused. May be engraved around the lens barrel, on the focusing control or on the camera body.

Scale
To change the proportion of an image by increasing or decreasing its size.

Scan Size
The length and width dimensions of the part of a document that can be digitized.

Scan Time:
The total time to convert text or graphical information into electronic raster form.

Scanned image
The computer picture that results when a photograph, slide, paper imager, or other two or three dimensional images are converted into a digital image.

Scanner Threshold
Setting that determines whether a pixel is white or black.

Scanner
A device that captures an image for your computer and converts it to a digital form that your computer can display, edit store and output. A scanner can be used for a wide variety of application, such as incorporating artwork or photos into documents, scanning printed text into your word processor to eliminate retyping, scanning faxed document into a database for storage, and adding images to multimedia productions.

Scanning back
High quality digital camera back for medium or large format cameras which scans in three passes (RGB) one pass for each colour, therefore best used with still life subjects.

Scene Modes : Pre-set exposure control (shutter/aperture combination, plus other adjustments, such as white balance, exposure compensation, etc.) for various common picture situations, such as Night Scene, Portrait, Landscape, Action, etc.

Scheimpflug rule
A useful rule when using camera movements is that when the planes of the subject, the lens panel, and the image are made to coincide at a single line, everything will be in focus.

Scratch disk
A virtual memory scheme used to temporarily use hard disk space as a substitution for RAM.

Screen angle
The angle at which the halftone screens are placed in relation to one another.

Screen frequency
The number of lines or dots per inch in a halftone screen.

Screen resolution
The size of the rectangular grid of pixels displayed on a monitor.

Screen ruling
Number of raster points either per inch or per centimetre. Measured in lines per cm (l/cm) or lines per inch (lpi). A 60 l/cm raster therefore corresponds with 152 lpi.

Screen
In a camera. the surface upon which the lens projects an image for viewfinding and, usually, focusing purposes. In SLR cameras. almost universally a Fresnel screen with a fine-ground surface. Often incorporates a microprism or split-image rangefinder.

Screening
Another name for halftoning.

SCSI chain
A chain that links SCSI devices on your system. A SCSI chain may include such devices as a scanner, a CD-ROM drive, an external hard drive, and a tape drive. Each SCSI device on the chain must have its own SCSI ID number, or conflict will ensue.

SCSI
A high-speed input/output bus used mainly in Macintosh computers but also popular in many high-end PC's.

SDC System Developing Companies
Kodak and four other photo industry leaders who jointly developed the Advanced Photo System standards.

SDRAM
Synchronous dynamic random access memory; often used in digital cameras and other computing devices. SDRAM is a relatively new type of memory that runs at higher clock speeds than traditional memory.

Secure Digital memory
Memory card about the size of a postage stamp that weighs approximately two grams; available with storage capacities as high as 128MB. Secure Digital memory is gaining favor in all types of personal electronics devices.

Selection (tool or box)
A tool in some software that allows you to target a specific area of an image for some type of manipulation; this can be a pointer arrow, crosshairs, a lasso, a box made of dotted lines.

Selective focus
Choosing a lens opening that produces a shallow depth of field. Usually this is used to isolate a subject by causing most other elements in the scene to be blurred.

Selenium
Light-sensitive substance which, when used in a barrier-layer construction, generates electrical current when exposed to light. Used in exposure meters. Needs no external power supply.

Self-timer
Mechanism delaying the opening of the shutter for some seconds after the release has been operated. Also known as delayed action.

Semi-automatic iris
Diaphragm mechanism which closes down to the taking aperture when the shutter is released, but must be manually re-opened to full aperture.

Sensitive
In photography, refers to materials that react to the actinic power of light.

Sensitivity
Expression of the nature of a photographic emulsion's response to light. Can be concerned with degree of sensitivity as expressed by film speed or response to light of various colours (spectral sensitivity).

Sensitometer
An instrument with which a photographic emulsion is given a graduated series of exposure to light of controlled spectral quality, intensity, and duration. Depending upon whether the exposures vary in brightness or duration, the instrument may be called an intensity scale or a time scale sensitometer. Is the scientific study of the response of photographic materials to exposure and development. It establishes emulsion speeds and recommended development and processing times.

Sepia
A brownish coloured, old-fashioned look to an image often created as a special effect either within a digital camera or in an image editing software.

Serial Interface
(Also called RS232C or RS422 interface) An interface which allows peripheral devices such as a mouse, modem and certain digital cameras to be connected to the computer. Data is transferred serially, which means bit by bit, one piece after another, via a connection cable.

Serial port
Is a general-purpose personal computer communications port in which 1 bit of information is transferred at a time. In the past, most digital cameras were connected to a computer's serial port in order to transfer images to the computer. recently, however, the serial port is being replaced by the much faster USB port on digital cameras as well as computers.

Serial transfer
Connecting a digital camera to a computer via the serial port ( also known as the COM port on PC's or Printer / Modem port on Apple Macs ) in order to download images. Quite slow.

Server
One computer that acts as a networking device for many interconnected computers.

Service bureau
A business that specializes in outputting computer files on laser imagesetters, film recorders, large-format plotters and other types of output devices.

Shade
The brightness or luminance of an image when compared to a gray scale.

Shadow Point
The darkest tone printable in an image without being black. All tonal values below this threshold will print as black.

Shadow
A term that refers to the amount of detail contained in the dark parts of an image. It is desirable to maintain shadow detail but there is a risk of decreasing overall contrast if one lightens the shadow too much in an attempt to expose detail. If an image is scanned without shadow detail, it will be impossible to regain detail in an image editing program.

Sharpen edges
An image editor technique to enhance the edge of an object.

Sharpen
Electronic photo-retouching function for enhancing image detail and contrast either globally or in selected regions of the picture.

Sharpening
Sharpening in a digital sense is the enhancing of edge detail. It is performed by a mathematical formula which is applied across the image. Put simply it enhances the visibility of a boundary between light and dark tones in an image.
In-camera sharpening - Most consumer digital cameras will, as a part of normal image processing apply some level of sharpening, to counteract the effects of the interpolation of colours during the colour filter array decoding process (which will soften detail slightly). The problem with in-camera sharpening is that it increases the visibility of jaggies and can increase the visibility of other image artifacts.
Recently, digital cameras have allowed users to control the amount of sharpening applied to an image (menu option), the primary reason for this is the widespread use of image processing applications, the "digital darkroom" and the ability to control artifacts related to sharpening. Higher-end digital SLR's and other cameras which support RAW format don't apply any sharpening to the RAW image, this allows the user to decide on the level of sharpening when acquiring the image later.
Image editor sharpening - Quite a few digital camera owners choose to sharpen images even further, often to "pull out" fine details of reduced size images for web or monitor viewing purposes (sharpening for printing isn't really recommended and can make the image look fake and over-processed). Probably the most popular sharpening method is the "Unsharp Mask" (a very confusing name) which produces the most pleasing sharpening results without making the image look over-processed. It also allows for a wide variation of parameters to be used, which increases the ability to match the sharpening level to the particular image / desired output.
Smart Media adapter: An adapter in the shape of a 3.5" floppy disk, made to accept a SSFDC memory card so it can transfer the data into the computer by the floppy drive.

Sharpness
A term used to describe the ability of a lens to render fine detail clearly; dependent on the contrast and resolution of a lens and varies with the f/stop; in general, a lens is sharpest at the middle apertures. Also technically can be explained as clarity of the photographic image in terms of focus and contrast. Largely subjective but can be measured to some extent by assessing adjacency effects, i.e. the abruptness of the change in density between adjoining areas of different tone value. An image degree of clarity in terms of focus and contrast.

Sheet film
Film that is cut into individual flat piece. Used in large format view camera, with sizes like 4x5, 8x10 and 11x14 inches. Also called cut film.

Shelf life
Is the length of time unused material or chemicals will remain fresh.

Shift
Movement on large format camera ( or special " shift lens " in other formats ) which can eliminate converging angles.

Shooting distance
Refers to the distance between the subject and the film plane.

Shooting Modes
The amount of control you have in choosing how your digital camera captures an image. All digital cameras usually have an Auto mode: the camera decides for you the best shutter speed/aperture settings.

Short lens
Term describing a wide-angle lens (a lens whose focal length is shorter than the diagonal measurement of the film used).

Short Lighting
Portraits are often done with the model not facing directly towards the camera but turned slightly away. If the lighting is such that the majority of the subjects face is shadowed, this is referred to as short lighting.

Shutter Priority
An exposure mode on an automatic or autofocus camera that lets you select the desired shutter speed; the camera sets the aperture for proper exposure. If you change the shutter speed, or the light level changes, the camera adjusts the aperture automatically. There are times when a specific shutter speed is desired regardless of the aperture needed. Shutter priority allows the user to set a shutter speed and then the camera will chose the proper aperture setting based on in camera metering. Allows you to decide the shutter speed (e.g. fast at 1/500 sec. for stop action photography, or slow at 2 sec. for night photography), and the camera decides the best aperture.

Shutter release
The mechanical or electromechanical button that releases the shutter and takes the exposure.

Shutter Speed
The length of time in which the film is exposed to light is known as the shutter speed. Faster shutter speeds allow for crisper pictures because camera shake and subject movements will be minimized. Slower shutter speeds can be used to create blurring effects or may be needed to properly expose darker subjects. The duration that the shutter is held open during an exposure. A typical range is from 1 full second to 1/1000 of a second. Combined with the lens aperture it controls the total amount of exposure.

Shutter
Blades, a curtain, plate, or some other movable cover in a camera that controls the time during which light reaches the film.

Sidelighting
Light striking the subject from the side relative to the position of the camera; produces shadows and highlights to create modelling on the subject.

Signal-to-noise ratio
The ratio of the usable signal to unusable noise in a scan. A high degree of noise can mask the shadow detail in an image regardless of tonal resolution.

Silhouette
A dark image outlined against a lighter background.

Silicon
Light-sensitive substance which generates a minute current when exposed to light.

Silver halide
A chemical compound of silver (usually silver bromide, silver chloride and silver iodide) used as the light-sensitive constituent (emulsion) in films. The invisible image produced when the halides are exposed to light is converted to metallic silver when the film is subsequently developed.

Silver print
A generic term referring to all prints made on paper coated with silver salts. Most contemporary black and white photographs are silver prints.

SIMM
Single In-line Memory Module. A common type of plug-in RAM memory module for personal computers.

Single Lens Reflex (SLR)
The most common type of non point and shoot cameras on the market today are probably known as Single Lens Reflex (SLR) Cameras. These cameras allow the user to view the subject being photographed through the same lens that the film will "see". This allows the user to avoid the parallax effect observed with Twin Lens Reflex camera as well as see in the view finder exactly what the photo will look like. A type of camera that allows you to see through the camera's lens as you look in the camera's viewfinder. Other camera functions, such as light metering and flash control, also operate through the camera's lens.

Single Servo AF (Nikon's term)
Once the subject is in focus, focus is locked. Useful for recomposing the picture.

Single-Lens-Reflex (SLR) Camera
A type of camera that allows you to see through the camera's lens as you look in the camera's viewfinder. Other camera functions, such as light metering and flash control, also operate through the camera's lens.

Skew
During printing or scanning, the content of a page are almost never exactly vertical, which referred to as being skewed. De-skewing is a process where the computer detects and corrects the skew in an image file.

Skylight filter
A UV filter with a pale rose tinge to it eliminate a blue colour cast caused by haze, it may be kept in place permanently to protect the lens from dust and scratching.

Slave unit
A light sensitive trigger device used to synch strobes and flashes without an electronic synch cord. Accessory flash "slave" units are available to fire multiple flash units without multiple electrical connections to the camera. These units sense the light output of the first flash, which is mounted in the camera hot shoe, or cord-connected to the camera. When the light output is sensed, the slave unit triggers a second flash unit that is connected only to the slave. Additional slaves and flash units can be used, if needed. T here are times when multiple flash units will be used to light a set or scene. It would become a complex array of PC Cords if slaves were not available. Slaves come in 3 flavors, those triggered by visible light, those triggered by infrared light, and radio slaves. All three serve the same purpose: to fire a remote flash unit with out wiring. Light operated slaves are triggered when light of a specific wavelength falls upon a photocell in the front of the slave unit, causing the flash to fire. Radio slaves rely on radio signals between a transmitter and receiver to tell the remote flash unit when to fire. The advantage of the radio slave is that it is not line of site, flash units hidden behind objects can be fired with radio where optical methods would not work. Radio slaves also cannot be triggered by other flash units, such as guests at a wedding taking snapshots.

Slide film
Film used in making slides. Also known as " Transparency film ," " Positive film " or " Reversal film. " Slide film, also known as Chrome Film, records the image as a positive. Reversal paper is used to make a print from this medium, and is more expensive. Slide film has a very narrow range of proper exposure, usually +/- .5 stops.

Slide scanner
A scanner with a slot to insert 35mm slides; usually capable of scanning only 35mm transparent material.

Slide
A photographic transparency (positive) mounted for projection. Represent first generation production of a image. Most agencies and photo editors demands slides than prints. Having a very tight tolerance on exposure latitudes. A transparency (often a positive image in colour) mounted between glass or in a frame of cardboard or other material so that it may be inserted into a projector.

Slot
Expansion interface in computers, notebooks and other devices. Expansion cards, e.g. PC Cards, can be plugged or built in here to increase performance, capacity or the capabilities of the device.

Slow film
Is film having an emulsion with low sensitivity to light. Typically films having an ISO or 50 or less.

Slow lens
Film which has a small maximum aperture. (i.e. f8 )

Slow Sync
A flash technique for using the flash at a slow shutter speed. Flash shooting in dim light or at night at a fast shutter speed often results in a flash-illuminated subject against a dark background. Using a slower shutter speed with the flash brings out the background details in the picture. Use of a slow shutter speed with Rear-Curtain Sync is particularly effective for illustrating the movement of a stream of light. Can be of very creative if put to good use.

SmartMedia memory
A memory card developed by Toshiba that uses flash memory to store data. It measures 45 x 37 mm and is less than 1 mm thick. Available in capacities to 128MB, SmartMedia is portable and can easily be transferred between electronics devices.

Smoothing
Averaging pixels with their neighbors. It reduces contrast and stimulates an out-of-focus image.

Snapshot
An informal photograph, especially one taken quickly by a simple, hand-held camera.

Snoot
A soft box makes the light more diffuse; a snoot causes it to be more directional. There are times when a photographer desires the photo to appear as if the light was coming from a specific point or to only illuminate a specific portion of the scene. A snoot is added to the front of the flash head to direct the light to the area desired.

Sodium thiosulfate
The active ingredient in most fixer.

Soft focus lens
Is a lens, uncorrected for spherical aberrations, used to produce a soft focus effect.

Soft Focus
Filter used often by glamour photographers and occasionally by other photographers to cause a slight blurring of the highlights into the shadows which produces a photograph with softened edges. Filters are available for this technique but be warned, these filters can be over used and can detract from the images. Is the definition of a diffused image. this can be achieved at the camera or enlarging stage. Produced by use of a special lens that creates soft outlines. Filters are more popular than lens as it is more economical and flexible.

Soft Lighting
Lighting that is low or moderate in contrast, such as on an overcast day. Low contrast illumination.

Soft Proof
Viewing a digital image with a monitor instead of generating a hard copy proof.

Softbox
Large, diffuse light, usually with electronic flash as the light source. Over cast days produce very soft lighting with little contrast compared with a bright sunlit day which will produce harsh shadows and strong highlights. The use of a softbox is to soften to light, make it less harsh. Softer lighting produced much more pleasing photos when shooting portraits and product shots where harsh shadows or highlights are not desired.

Soft-Edge Masking
A technique used to isolate a portion of an image with an edge that allows for a smoother transition to areas around the masked part.

Spatial Resolution
The finest image portion that can be seen at any magnification.

SPD
Silicon Photo Diode. Battery powered light sensitive cells - the most common light reading cells for cameras, external metering devices.

Speckling
Isolated light pixels in predominantly dark image areas, sometimes caused by incorrect readings or noise in the scanning device.

Spectral data
Colour information stored as multiple measurements (typically 16 32, or more ) across the range of wavelengths of visible light.

Spectrophotometer
A device that captures colours as spectral data, thereby providing maximum accuracy in measuring and specifying colours.

Specular highlight
A bright reflection from a light source containing little or no detail. Specular highlight within an image should not be used for Set Whitepoint.Light rays that are highly redirected at or near the same angle of incidence to a surface. Observation at this angle allows the viewer to "see" the light source.

Speed
A measure of the sensitivity to light of a photographic emulsion.

Spherical aberration
Light passing through a convex lens will be brought to different focus depending upon whether the light passes through near the center of the lens or closer to the periphery. Lens designers strive to correct this kind of zonal aberration to bring peripheral and near-central rays to a common focus.

Split-image
Form of rangefinder image, bisected so that the two halves of the image are aligned only when the correct object distance is set on the instrument or. in the case of a coupled rangefinder, when the lens is correctly focused. SLR cameras may have a prismatic split-image system in their viewing screen. Works on the same principle as a microprism, and is restricted to apertures of f5.6 or greater.

Sponge
This toning tool is used to saturate or de-saturate areas of an image.

Spot meter
An exposure meter that measures the light reflected from a small area of the subject Hand-held spot meters may measure an area as small as one degree; those built into the camera may measure a somewhat larger area. Some scenes involve difficult lighting situations where a matrix metering or center weighted metering system of a standard camera would incorrectly meter. Spot metering allows a user to pick a specific point in the scene and meter it only. This allows a user to expose for a specific point in the scene.

Spotlight
Is an artificial light source using a Fresnel lens, reflector, and simple focusing system to produce a strong beam of light of controllable width.

SQF
Subjective Quality Factor. Essentially a lens rating system.

S-RAM
(Static RAM) The most expensive type of RAM found in on-board memory units, some printers, and in PCMCIA Type I Cards. D-RAM, Dynamic Ram. Most often seen as the expandable RAM used by the computer for memory.

sRGB
A calibrated RGB colour space, proposed as a Web standard.

SSFDC
(for solid-state floppy disk) , a removable Flash Ram Memory Card used in digital cameras and other digital product. Both 3.3 Volt and 5-Volt card exist. SSFDCs are also called Smart Media Cards.

Stabilizer
A processing solution used in colour processing to make the dyes produced by development more stables. Alternative to fixer where permanence is not required. Used in automatic processing machines and can now provide prints that will not deteriorate noticeably over many months if kept away from strong light.

Stain
Discoloured areas on film or paper, usually caused by contaminated developing solutions or by insufficient fixing, washing, or agitation.

Staircasing
See aliasing

Stand
Is an alternative name for a tripod.

Standard deviation
A measure of dispersion of a frequency distribution.

Standard Format
35 mm cameras are often referred to as Standard Format because the film and cameras are readily available to almost anyone in almost any price range. Negative size is 24mm x 36mm.

Standard lens
Lens with a focal length approximately equal to the diagonal of the film format with which it is used.

Step wedge
A printed series of density increases, in regular steps from transparent to opaque. its a method of making exposure tests when enlarging.

Stock Photos
An already existing picture that can be purchased for use instead of having a photograph specifically made.

Stock solution
A concentrated chemical solution that is diluted before use.

Stop bath
An acid solution used between the developer and the fixer. The stop bath halts development and at the same time neutralizes the alkaline developer, thus preventing it from lowering the acidity of the fixer. Generally a diluted solution of acetic acid; plain water is sometimes used as a stop bath for film development. Darkroom material. An acid rinse, usually a weak solution of acetic acid, used as a second step when developing black-and-white film or paper. It stops development and makes the hypo (fixing bath) last longer.

Stop-down metering
TTL metering in which the light is measured at the picture-taking aperture. As the meter just measures the light passing through the lens, there is no need for any lens-camera interconnections.

Stopping Down
Changing the lens aperture to a smaller opening; for example, from f/8 to f/11. Some lenses, like PC lens or attachment with a none dedicated bellow on macro photography, stop down exposure metering is required for correct reading. In photography, to decrease the size of aperture in a lens, e.g., to "stop down" from f/3.5 to f/16 (larger aperture numbers signify smaller apertures). Increases depth of field and reduces the amount of light allowed to expose the film. Opposite: open up.

Storage cards
The storage card in a digital camera is it's film, it's the removable storage device which holds images taken with the camera (a few low-end digital cameras don't have removable storage cards but instead have a built-in flash RAM unit). When the card is full it can be removed and another card inserted. The memory on these cards is non-volatile-m that is, they don't lose their images when they are removed form the camera. The images can be later downloaded from the card, and when the images are erased from the card it is ready to be reused. These cards are good for a lot of reuses- one manufacturer just warranted their cards for a minimum of 1,000,000 images. Four types of memory cards exist at this time: Compact Flash, Smart Media, Intel Miniature Card and PCMCIA. Compact Flash type cards are used by many digital camera manufacturers and when placed in an adapter, can be inserted in the PCMCIA slot of a computer. Smart Media Cards, also used in a number of cameras can be inserted into a floppy disk adapter (3.5") and read as if they were a floppy. Yet another adapter allows them to be used in a PCMCIA slot.

Streak noise
Vertically correlated noise in a scan or other image capture that appears as white streaks in the output.

Strobe duration
The amount of time, expressed in microseconds, during which the flash lamp (strobe) is at 90% intensity.

Strobe
Unlike a monolight, a strobe requires a separate battery or power unit to supply the head with power. Strobe heads are smaller and lighter than monolight heads and can be used in the same fashion as monolights.

Studio lamps (3200K)
Tungsten or tungsten halogen lamps designed for studio use. Have a longer life than photo lamps, but a lower specific output and colour temperature. Are used with type B films.

Studio
A room specially equipped for photography.

Stylus
A tool that is used on a graphic input tablet as a drawing instrument, or as a mouse.

Subsampling
Using an algorithm to derive a lower-resolution image from a higher-resolution image.

Subtractive colour
Combining cyan, magenta and yellow inks (or other colourants ) to create black; each ink subtracts from the white incident light, until nothing is left except black.

Superimpose
To place one element over another to create stacking of images or overlays.

Supplementary Lens
Generally a simple positive (converging) lens used in front of the camera lens to enable it to focus at close range. The effect is to provide a lens of shorter focal length without altering the lens-film separation, thus giving the extra extension required for close focusing.

SVHS
Super Video Home system. Clearer than the conventional VHS because it separates chrominance and luminance transmission

Swing back / front
term used to describe the movable lens and back panels of most view and monorail cameras. They allow manipulation of perspective and depth of field.

Sync Cords
The purpose of sync cords is to allow the camera to control the flash, so the flash fires at the correct time. Other common names for electrical cords to connect flash to camera are PC cord, sync cord and synch cord. One type of electrical connector on camera bodies is called a PC socket, whence the name, PC cord. Sync and synch are both intended to be abbreviations of the word synchronization.

Sync Delay
All electronic flash units require X sync, but flashbulbs require a time delay between firing the flash and opening the camera shutter. The optimum delay varies among flashbulb types, but you will get much of the flashbulb light through the shutter and onto the film even if delay is not exactly correct. Firing delay for flashbulbs is indicated by code letters "F"- fast; "M"- medium; "MF" - medium fast; "S" - slow

Sync Socket
Often called "PC terminal" or "PC Socket". Most older manual focus SLR camera bodies have this standard PC sockets which have a threaded collar surrounding the center electrical part of the socket. Some older flash units may not have a hot shoe on the flash unit and would need cable connection to fire the flash (sync) timely with the shutter. Some flash cords have a connector that makes electrical contact with the center part of the socket and is held securely in place by a threaded ring which screws into the outer part of the socket on the camera body. It is also use for multiple flash setup (non-TTL or manual) where the secondary flash can be used via a sync cord to fire at the same time.

Sync speed
Exposure time with a focal-plane shutter is measured from the instant the first curtain is released, to begin its travel across the frame, until the instant the second curtain is released, to begin its travel across the frame. When the first curtain reaches the end of its travel, the film frame is uncovered as far as the first curtain is concerned, so it closes the electrical contacts for X sync and fires the flash instantly. Shutter speed at which the entire film frame is exposed when the flash s fired in flash shooting. Most modern camera with vertical travel shutter curtain have faster flash sync speed like 1/250 sec. or slower, some top camera model like Nikon F5, changeable to 1/300 sec. with the Custom Setting.

Synchronisation
Concerted action of shutter opening and closing of electrical contacts to fire a flashbulb or electronic flash at the correct moment to make most efficient use of the light output. Roughly speaking, FP or M-synchronisation is constructed to fire flashbulbs just before the shutter is fully open, allowing a build-up time, and X-synchronisation fires electronic flash exactly at the moment the shutter is fully open.

Synthetic profile
An ICC profile created in Photoshop with specific gamma, white point, and primary values, used for correcting images with severe exposure problems.