Ag Photographic

GLOSSARY

If you are new to 'real' traditional photography, some of the terminology can be a little daunting - but it really is very simple to get to grips with! We hope this glossary helps, but please remember, you can always call us on 0121 444 5352 for friendly advise!

ASA
Short for Americal Standards Association - simply, this is film speed and if you are used to digital, it's the same as 'ISO'. Essentially it is a measurement of the sensitivity of the film: a 100 ASA film is twice as sensitive as a 50ASA film, and  a 200ASA film is twice as sensitive as a 100 ASA film, and so on. Sometimes films are 125 ASA (such as Ilford FP4) so it is slightly more sensitive than a 100 ASA film.

Archival Washer
This is a tool for washing Fibre Based prints thoroughly to ensure all trace of processing chemistry is removed. Usually they consist of a bath with dividers to keep the prints separate. Water enters at one end and flows out at the other keeping a continuous flow of water over the prints.

Baryta
This is a special clay type material also known as barium sulphate. It is used in the manufacture of high quality fibre based black and white papers and some inkjet papers. It's original use was in traditional papers and has only recently started to be used in Inkjet papers.

C41
This is the standard process for all colour negative (print) film. It is the most common process in use in commercial labs and mini-labs situated in grocery stores and pharmacies. Some black and white films are processed in this way such as Ilford XP2, Kodak BW400CN, so to allow convenient processing without the need to find a B&W lab or process youself.

Coating
All film and Paper (including decent Inkjet paper) must be coated with a light sensitive Emulsion (or ink receiving emulsion in the case of Inkjet). This is a very finely controlled industrial process whereby the base (paper or film) is fed past a coating head where the emulsion, in liquid form, is laid onto the base - in the case of most film and paper coating, normally at a speed of 1 or 2 metres per second, or something like that. The coated base is then cooled, warmed and treated in various ways. Coating machines are very large (Ilford's is 500ft long) and extrememly expensive if ever one was to be installed (10's of millions, even 100's of millions). It is worth noting that it isn't only photo products that require coating - there are many other products.

Cross Process
Normally this is where a Colour Transparancy film (slide film) is processed in C41 colour negative chemistry. The result is normally a high contrast negative with some unusual colour balance. Excellent for the right subject. Cross processing can work the other way (colour negative film in E6 chemistry) but it is rarely as successful.

Emulsion
This is a word often used in relation to film and paper, but it has nothing to do with the paint you put on your walls! Both Film and paper is manufactured by coating a base with an "emulsion" - the emulsion is a mixture of gelatin and silver salts. It is the substance that actually records the image.

E6
This is the standard process for Colour Transparency film (AKA Slide film or Reversal film) where a positive image is yielded, as opposed to a negative. Sometimes colour transparency film can be Cross-Processed in C41 chemistry to yield a negative with special features. The resulting film can be cut and mounted for viewing via a slide projector. Generally speaking, Slide film scans better, in terms of grain, than negative film - but this is a debate in itself!

Fibre Based Paper
This is the original, traditional, black and white paper. Chiefly this paper is used by those seeking the ultimate in image quality, tonality and depth. Many photographers interested in fine art work use Fibre Based paper extensively. Until the 1970's all paper was fibre based. The disadvantage is that, because there is no plastic coating, like with Resin Coated paper, chemicals during processing are easily soaked into the paper and thus prints require very thorough washing, normally in an Archival Washer, in order to eliminate the traces of chemicals - failure to do this shortens the life of the print - if washed properly, the print can be expected to have the ultimate in archival longevity. These days Fibre based paper is only supplied as double / heavy weight, which only adds further to the feel of quality.

RA4
This is the standard process for colour negative paper such as Kodak Endura or Fuji Crystal Archive. IT consists of two baths - Colour Developer and Blix, with an optional third bath, stop, inbetween. This is the industry standard process for all colour paper.

Reversal Film
This is colour or Black and White film (although there are no specifically reversal black and white films on the market for stills photography, only a couple for motion picture) that, in the case of colour reversal, is processed in E6 chemistry to yield a positive. In the case of 35mm and 120 film, it can then be cut up and mounted for viewing with the use of a slide projector. Normal black and white negative film can be processed in a special way (reversal processing) to turn it in to a positive.

Reversal Processing Black & White
This is the use of a specific chemicals and process to develop normal black and white negative film as a positive. The process normally involves a re-exposure step. Some black and white films lend themselves better than others for this process. Kodak offer a processing kit to perform this with T-Max 100.

Slide Film
See Reversal Film

Transparency Film
See Reversal Film