Equipment: the enlarger
Figure 12.10 Making big enlargements: typical limiting factors are the height of column, and the column base fouling the image area (left). Solutions include (A) angled, extended column and larger baseboard; (B) turning the enlarger head to project from bench down on to the floor; or (C) rotating the head to project on to a distant wall
Figure 12.11 Alternative ways to control variable contrast printing paper. A: drawer for (acetate) filters between lamp and negative. B: holder on lens for (gelatin) filters. C: lamphouse with internal dial-in VC filtration system. D: Colour printing lamphouse (see Figure 12.22)
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horizontally on to a distant wall. Some bench models turn to work vertically downwards onto the floor; see Figure 12.10. At the other extreme, for prints smaller than the negative dimensions, you need to be able to lower the enlarger head and position the lens sufficiently far away from the negative; see Figure 12.9. If the bellows will not stretch this far, try fitting a camera-type lens extension ring. Contrast control filters
In order to alter the contrast of variable contrast printing papers (page 236), all modern black and white enlargers offer some way of tinting the light. This can be a simple filter drawer between lamp and diffuser or condenser. You buy a set of six or more ‘above-the-lens’ acetate filters, Figure 12.12, to use in the drawer one at a time. Changing the filter colour changes the contrast characteristics of your printing paper. Alternatively you can clamp a filter holder below the lens and using a set of smaller gelatin filters alters the light at this point. (Filters must be the more expensive gelatin type, otherwise their use below-the-lens will upset image definition. You must keep these filters completely free of finger marks too.) Far more convenient, a variable contrast lamphouse unit allows you to continuously vary filtration, just by turning a numbered dial which moves built-in filters in or out of the light beam above the negative. If you plan later to colour print, a colour lamphouse unit (with yellow, magenta and cyan dial-in filters) will also serve variable contrast