Picture research involves visiting the library and searching through stock using a hand lens on a light box until the right material is encountered. Alternatively, professional researchers can be employed to do the searching for you, or librarians employed by the picture library can be asked to supply specified material. If this requires an undue amount of searching, you may be asked to pay a research fee.
Film libraries operate in much the same way.
If your requirements are modest, picture agency staff may be willing to retrieve a sample of transparaencies for you and send them to you by courier for final selection. In these cases, you will be given six to eight weeks in which to make up your mind, after which a fee may be charged. Fees vary according to the size of the market in which they will be sold, so if you only want them for use in the UK be sure to say so. Some libraries are prepared to do special deals for education, others are not, and some increase the fees for electronic uses because there is no limit to the number of times a digital image can be used and re-used in an electronic application.