DIY Solux fixtures

One aspect of monitor to print matching is often overlooked: good lighting. Among the better choices (short of professional viewing booths) are the Solux halogen bulbs, because they are reasonable priced and provide a very smooth spectrum. Using them can be a bit tricky, though, as the following things have to be taken into account.

  • Being spot lights, with a maximum beam width of 36 degrees, you have to be careful to avoid light falloff across your print.
  • At 35 or 50 Watts per bulb, they generate a lot of heat.
  • Surrounding the central spot, the Solux bulbs output a ring of light that is noticably warmer. This is probably because of the unfiltered (unreflected) light coming straight from the filament of the bulb. Also, there is some very colorful light coming out of the back of the bulbs.
The setup (two out of three fixtures shown)

You can get around these problems by using a setup that consists of multiple spots, in which each bulb is enclosed in a heat-resistant fixture with a snoot and an end cap to remove the unwanted warm light. Tailored Lighting, the company behind the Solux lights sells such fixtures, but they don't come cheap. Therefore, I constructed my own setup.

I started out with a fairly standard halogen wire system, in which the fixtures are hanging from two tensed wires. The fixtures themselves consist of two 50cm-long stiff rods with a simple socket for a bulb. Such a wire system gives me plenty of clearance between the hot bulbs and the ceiling or other materials that could be affected by the heat the bulbs put out. For my uses, I have selected a 150W transformer and 3 fictures with 50W 4700K Solux bulbs (36 degree spot).

The system as described provides even (enough) illumination and takes care of the heat, but the standard fixtures leave the bare Solux bulbs out in the open, leading to a noticable warming of the light due to the warm 'halos' around the central spots. This I resolved by creating an enclosure around the bulb from empty paint cans bought at the local paint shop. The cans have a diameter that is approx. 2cm larger than that of the bulb, to allow for some clearance between the bulb and the can.

A top view of one of the fixtures.

I removed the bottom of each can using a can opener. In the lid, I created a central hole for the lamp foot and six smaller holes surrounding it for ventilation. The hole in the middle is made to such a size that the foot of the bulb fits, but does not go all the way through (the foot is slightly tapered). This maximizes the distance from the back of the bulb to the lid of the can in the back of it. Finally, I painted the inside of the cans with a black heat-resistant radiator paint, to absorb as much of the stray light as possible. The resulting viewing light is quite satisfying. I determined the color temperature to be around 4600K by measuring the light reflected off a WhiBal white balance reference card, both with an X-Rite DTP-94 display calibrator and my Olympus E-1 (measure raw white balance in ACR). These measurement methods are imperfect, but they are the best tools at my disposal. Also, I determined the illumination to be between 200 and 500 lux, depending on the distance between the print and the bulbs.