Wednesday, 17 December 2014

Glossary of film photography terms

Glossary
120 size film
Roll film that measures 60 mm across and is long enough for 8 off 6x9, 12 off 6x6 or 16 off 6x4.5 negatives. Still available.
127 film
Roll film that measures 46 mm across and is long enough for 8 off 4x6, 12 off 4x4 or 16 off 4x3 negatives. Now obsolete.
35 mm film
Small film format based on cine film provided in a light proof cassette to allow daylight loading of the camera. Has two rows of perforations used to both locate and to move the film. Image size is usually 24mm by 36mm. Still available.
aperture
The hole through which light passes to get into the camera. In many cameras, this is adjustable.
aperture priority 
An automatic exposure system that allows the user to set the aperture and then calculates the required shutter speed.
automatic exposure
A system whereby the camera decides on what combination of aperture and shutter speed to use.
automatic focussing
A system where the camera focusses the lens on the subject behind one of several pre-set focus points.
baseboard
The hinged 'door' of a folding camera that holds the lens and shutter in place.
bayonet
a system of fitting a removable lens quickly. This only requires about 1/3 of a turn of the lens compared to several turns for a threaded lens.
bellows
a leather or fabric tunnel between the lens and the camera body that collapses when the camera is closed.
BII
The German name for 120 film.
Body release
a shutter release on the body of the camera rather than on the shutter housing. This became normal from the mid 1930s.
bokeh
A Japanese word used to describe the out-of-focus areas of an image. Currently very fashionable but unheard of a few years ago.
brilliant finder
A small viewfinder viewed from above and gives an image that is reversed left to right.
bulb release
similar to a cable release but is a hollow tube with a pneumatic bulb on the end. The shutter is tripped by squeezing the bulb.
cable release
a flexible cable to allow tripping the shutter without touching the camera – this avoids camera shake with slow exposures. The cable is usually wire in a wound metal sleeve.
cartridge
a disposable light-proof container for film. The most common are 126 and 110. Both are disposable.
cassette
A holder for film. Usually the Kodak designed cassette still in use but Leica, Zeiss Ikon and Agfa all produced their own designs at one time.
Chrome
a slang word for colour slide/reversal film
contact print
A print of a photograph on paper the same size as the negative.
depth of field
the spread of distances in the subject that are in focus on the negative
dial-set shutter
On older manual cameras, a separate dial, usually above the shutter that is used to set the shutter speed. Phased out around 1930. cf rim-set shutter.
diaphragm
A series of interlocking blades that can be moved to make differing sizes of holes to adjust the lens aperture. Often referred to as an iris diaphragm.
disc film
A short-lived type of film with small negatives arrayed around a card disc.
double exposure lock
Once the shutter has been tripped, the shutter is locked until the film has been wound one.
Double-extension bellows
These allow the lens to be moved much further away from the plate/film and so allow the camera to be focussed much closer to the object being photographed. They are an early macro device.
emulsion
the light sensitive coating on film
EV settings
a system common in the 1950s and 60s where the shutter speed and aperture were linked in the shutter housing. The user set a EV value on a ring on the shutter housing and could then adjust either speed or aperture and maintain the set exposure.
exposure compensation
A way of over-riding automatic exposure systems where the user can decide to over or under expose the picture by a set amount.
exposure lock
Allows the camera the set the exposure while pointing away from the subject – for instance to avoid under-exposure if there is a lot of sky in the picture.
exposure meter
a device to measure the amount of light so a good exposure can be calculated – most include a calculator. See light meter
fascia
A decorative covering over the front of the camera.
film advance
The means of winding the film on – usually a knob until the mid-1950s and then a lever until the late 1970s when it became an electric motor.
film advance lever
A lever used to advance the film one frame.
film gate
the rectangular opening inside the camera against which the film sits. It provides the sharp edges to the image.
film speed
A measure of the sensitivity of film to light. Measured in DIN, ASA or ISO
film winder
An automatic device to wind the film on once a exposure has been made,
focal plane shutter
a shutter consisting of either two cloth blinds or metal slats that sit just in front of the film and move to allow light to reach the film.
focussing screen
This is usually ground glass. In a plate camera, the glass is placed where the sensitive plate will later be and is used to display they image – upside down and reversed left to right. In a SLR camera, the focussing screen is immediately below the pentaprism and is viewed through the pentaprism with the image the correct way round. Focussing screens frequently include focus aids such as micro-prisms and split-image discs.
frame counter
Either counts how many pictures have been taken or counts how many are left on the roll.
Fresnel screen
this is a type of lens designed by the Frenchman Augustin-Jean Fresnel (pronounced Fray-nl). It is basically a normal lens cut into small sections to allow it to be made much thinner. It is used in focussing screens as a Fresnel screen will be as bright at the edges as it is in the centre.
Front-cell focussing
Ideally, a lens should be focussed by moving the whole lens towards or away from the negative. When there is a shutter in-between the glass elements of the lens, this is mechanically difficult and expensive to make. Cheaper cameras just move the front element of the lens which has much the same focussing effect but reduces the quality of the image formed for close-up shots.
helical focussing 
A focusing system where the lens is fitted in a screw thread and is focused by turning the lens.
hyperfocal distance
this is the maximum range of focus the lens is capable of. It is found by setting the infinity mark on the focusing scale against the set aperture on the depth of field scale.
image circle 
The circular image produced by a lens. It is always bigger than the negative or sensor.
Iris diaphragm
A series of interlocking blades that can be moved to make differing sizes of holes to adjust the lens aperture.
Karat cassette
Agfa's answer to Kodak's 135 film in the (now ubiquitous) cassette. Introduced in 1936, it was almost identical to the Agfa Rapid cassette.
leaf shutter
A shutter either between the glass elements of the lens, or just behind them that consists of a number of thin metal plates that move to allow light into the camera
lens coating
a very thin coating applied to the surface of lenses to increase contrast and reduce flare. On early lenses (from 1930) this was just on the front surface of the front element a but later was applied to all glass surfaces. This became normal from around 1950.
lens hood
a shade for the front of a lens to prevent oblique light from entering the lens. This is more important with older, uncoated lenses as they will produce flare if used pointing towards a light source.
lens node
the effective centre of a lens. For a 50 mm lens this will be 50 mm in front of the film. Sometimes the node is actually outside the physical lens
lens standard 
The board or frame that holds the lens in place.
light meter
a device to measure the amount of light so a good exposure can be calculated – most include a calculator. See exposure meter
M39
The standard thread for fitting a lens to a camera introduced by Leitz for their Leica cameras in they 1920s. Also used by many other manufacturers.
M42
A standard thread for fitting a lens to a camera introduced by East German Zeiss Ikon in the late 1940s. Used for most 35mm SLR cameras until the 1980s and became known as the Pentax thread.
macro
Strictly used to indicate that the image on the negative is life size but is used by lens manufacturers to indicate the lens can be used for close-ups.
manual focussing
Where the photographer must adjust the focus of the lens instead of relying on the camera to do so.
Match-needle
a system used in light (exposure) meters where the user turns a dial until the meter needle and the dial needle are in the same place. At this point, the required exposure can be read off a scale.
mercury cells
A form of battery now banned throughout the world. Usually a modern battery can be used it it place, but there will be a voltage difference to take into account.
Micro-prisms
a focussing aid that keeps the image out of focus until it is correctly focussed. Usually found in Japanese SLRs of the 1960s, 70s and 80s.
Monochrome
a picture in one colour – usually black and white but necessarily so.
motor-drive
A powered device to wind on the film and take the next picture.
negative
The picture formed in the camera on the piece of film. It is called a negative because the dark parts of the scene will be light and the light parts of the scene will be dark.
Newtonian finder
A crude viewfinder either with no lens of with a simple magnifying lens
orthochromatic
sensitive to blue and green light. The name means 'correct colour'. Orthochromatic film can be handled with a normal darkroom safe-light.
panchromatic
sensitive all colours – the usual film that is currently available. Must be handled in complete darkness.
PC socket
Prontor-Compur. Named after the two most prominent shutter manufacturers from the mid-20th century. It is the standard connector for flash guns found on most cameras until the Hot Shoe became normal.
pentamirror
a cheap alternative for a pentaprism. It does the same job for a much lower price but does not produce as bright an image. Found on more modern and cheaper SLR cameras.
pentaprism
a glass prism inside a reflex viewfinder that turns the image the right way around for viewing. It is found in most SLR cameras.
plate camera
a camera designed to use glass plates rather than film.
rapid cassette
An attempt by Agfa to compete with Kodak's 126 film cartridge. Film was held loosely in the cassette and needed to be wound into an empty Rapid cassette. Used between 1964 and the early 1990s.
Reverse Galilean viewfinder.
This is effectively a small telescope as designed by Galileo used backwards – it makes the view appear smaller so that a large scene can be fitted into a small viewfinder.
rewind knob
On 35 mm cameras, the means of winding the film back into the cassette.
rim-set shutter
On older manual cameras, the ring around the lens that is used to alter the shutter speed. Dates from around 1930. cf Dial set shutter.
rise and fall mechanism
A way of raising the lens so that a different part of the image circle is over the negative. It is used when photographing high objects to avoid tilting the camera.
Self-capping shutter
This is a type of focal plane shutter – the type used in all SLR cameras. In early focal plane shutters, the shutter would stay open when rewound meaning the film plate had to be removed first and it could not be used for film. A self-capping shutter will remain closed while being rewound so can be used with a plate in place and can be used for film.
self-erecting
A camera that unfolds with the lens in the correct position for picture taking at the touch of a button.
self-timer
A device in the shutter that delays the shutter opening for ten seconds or so
shutter 
The means of letting light into the camera in a controlled way. Either inside the lens (leaf shutter) or in front of the film (focal plane shutter).
shutter cocking lever 
On older shutters (pre-1955-ish) a lever used to set the shutter ready for use.
shutter release
The button or lever used to fire the shutter.
Signal
some camera provide a visual signal that the film has been would on and the camera is ready to take the next picture. Usually takes the form of a dot by the film advance that turns red when the camera is ready.
SLR
Single Lens Reflex – a type of camera where the user views the scene through the taking lens to give very accurate composition.
Split image disc
This is frequently found in the centre of a SLR focussing screen. It will split a vertical line (occasionally horizontal or diagonal line) while it is out of focus, the line joining itself at the point of focus.
spool
A wooden, metal or plastic holder for rolls of film.
spool carriers
The part of the camera that holds the spool of film either ready for use or once used.
sprocket hole
the row of hole along the edge of film to allow the camera to move it. In 35mm film there is a row on either edge. In 126 cartridges there is only one row of sprocket holes.
TLR
Twin lens Reflex – a type of camera that has two identical lenses, one above the other. Both are focused by the same mechanism at the same time allowing for accurate focusing but at the cost of some parallax error in near shots.
tripod boss
A threaded hole to allow the camera to be fitted to a tripod. On older cameras it will be either 3/8 inch or ¼ inch Whitworth thread and on more modern cameras 3/8 or ¼ UNC thread.
TTL
Through The Lens – a light metering system that measures the light that is coming in the lens. This gives more accurate exposures than using a hand-held light meter will.
V
Vorlaufwerk which is German for self-timer.
vignetting
A darkening at the edges of the picture caused by the image circle being too close in size to the negative – Common with cheaper lenses.
Waterhouse stops
a sequence of holes of varying sizes either in a line or around a disc that can be moved in front of the lens to control the amount of light entering the camera.
winder
a device to automatically wind on the film
Zeiss bumps
Bumps on the outside of Zeiss Ikon cameras caused by the rivets used to hold components together chemically reacting with the body of the camera. This causes visible bumps under the leatherette covering.
zoom
a lens that has an adjustable focal length