The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

Home | About | Photography | Contact






Flare
Photographer, touch on the essential points of success and the sources of failure : - '* Owing to the fact that much of the commer-cial sulphite contains sulphate, or has become converted by oxida-tion, the use of sulphite as a fixing agent is often disappointing. We do not recommend a much stronger solution than 20 per cent., but it is desirable to use a much larger quantity than is ordinarily recommended - say 3 or 4 ozs. of the sulphite for half a sheet of paper; and a sufficient time should be allowed for it to Uct. That is to say, double the time should be allowed that is necessary for the apparent dissolution of the chloride of silver, when the print is viewed by transmitted light. If a print, such as on albumenised or any not very thick paper, be looked at against the light during fixation, it will reveal the gradual dis-appearance of the chloride of silver in cloudy masses, in much the same manner as with a glass negative ; and when, after an interval of time, such indications of the presence of unacted open chloride are removed, the print should be returned to the fixing bath (or to a fresh bath) for the same length of time again. This is a good old rule given in connection with hyposulphite fixing, and may with still greater advantage be applied in the case of sulphite of soda. (See Acid Sulphite Fixing Bath ; and for the combined fixing and toning ,bath, see Toning.) For much genera] information relative to fixing see Development and Developers.
Postponed Fixation of Negatives. Some tourists, after having developed their negatives, merely wash and dry while on tour; the fixation being postponed until the return home. This method appears satisfactory provided that the washing is sufficient to remove all traces of the developer.
Flare. A fogged patch, generally central, circular, or arch-shaped, on a developed plate, and of course recognisable by the eye on the focussing screen. Flare may be due to many causes. For example, an image reflected from the concave surface of one glass, then back from another, or an image of the diaphragm or its edges. In these cases only the more strongly illuminated portion of the " object" will cast an appreciable image, and the flare spot will not form a complete circle. Monckhoven, in his " Photographic Optics," states that it is often due to too "lose an adherence to the globular form by the optician who
323