Oldal 91 [91]
OCR
3) If working in the studio, position the object following the recommendations referred to in section b. 4) If working outside the studio or in the field, position the UV radiation sources and the camera around the subject accordingly. 5) Position the reference standards as recommended in section b. A scale may also be inserted in the image if reguired. 6) Puton UV safety glasses 7) Turn on the UV radiation sources and allow them to warm up for 20 mins if not already on from the previous workflow). 8) Turn the room lights off. 9) Ensure that both the subject and reference standards are evenly illuminated, checking with a light meter if preferred. Camera capture settings 10) Camera settings will vary according to the equipment used but some general camera settings are recommended in section b. Exposure settings 11) The exact exposure settings will vary with the equipment used but some general exposure recommendations were made in section b. 12) Particular recommendations for acquiring UV-induced visible luminescence images: (a) Aperture settings in the middle of your lens range (e.g. f8) are usually a good Starting point for maximum sharpness, but choose depth of field according to dimensionality of subject, as advised in section b. (b) Aperture settings will be dependent on the intensity of the luminescence emitted, which will in turn be dependent on the nature of the material being examined. For weakly emitting cases, large apertures (low f-stop number) may be required. (c) Shutter speed will generally be quite long (e.g. 1 sec) but will again be dependent on the intensity of the luminescence emitted. Adjust this as required for correct exposure. Obtain an image of the uniform reflective board 13) Place the uniform reflective board so that it is evenly illuminated and fills the frame of the camera. As far as possible the board should be in the same plane as the subject so that the illumination on it is representative of the illumination on the object. 14) Focus on the board. Defocus slightly. Take the image. Version No. 1.0 83 Date : 14/10/2013
