I rewired/refinished a 1C enlarger and set it up today. The bulbs which came with the enlarger range from 75 to 250 watts. 250 is very hot.

What is the best size bulb for enlargements of 5x7 to 8x10? The light socket slides up and down on a shaft? What is the purpose and where should it be positioned?

-- Richard Jepsen (rjepsen@mmcable.com), March 09, 2002

Answers

Richard: The unit takes a PH211-75 watts, PH212-150 watts and a PH213-250 watts. I use a PH211 in my enlarger. IF you use a standard bulb in the enlarger, you might get the bulb information (75 watts 130 volts) on each picture. I am getting the best results with the bulb all the way up. I do not know what the reasoning for the adjustment is.

Enjoy. :)

-- Mark A. Johnson (logical1@catholic.org), March 09, 2002.

The reason that you can adjust the position of the bulb is to compensate for less than perfect centering of the bulb in the base, and the filament in the bulb itself. It will allow you to get even illumination over the complete field of the print. Generally the light is not (unless you are very lucky) even over the full frame. By moving the bulb up and down, and tilting it sometimes, you can achieve a good balance beween the center brightness and edge falloff. If you have access to an Incident Light Meter, you can measure the brightness at the center and the edges, and work out the best compromise. And I would also suggest the 75 watt bulb.

Regarding Mark's comment about the standard light bulb, if you use a small aperture, you will possibly have enough depth of focus to see the information printed on the end of a standard light bulb.

-- Ian MacEahern (iwmac@sympatico.ca), March 09, 2002.