Bulb types for light box use

[Dagwood56]

Okay - I've decided to make a light box, I'm going with the typical cardboard box with sides cut out draped with white muslin etc. and the poster board for the background. {white or black, right? Depending on what I'm shooting?}

What I'm confused about is the type of light bulb. This project has to be done as cheap as possible and since I have the cardboard box, and the muslin [I used to sew] and two old gooseneck type desk lamps, all I need to buy is the poster board, some white duct tape and the light bulbs!

Every set of directions I've looked at, people seem to mention using all sorts of bulbs from regular light bulbs to daylight bulbs to a 6500k daylight flourescent bulb [??] not even sure what they are! I need to have a bulb that will work in a standard lamp socket. A bulb that will obviously produce the right type of light. So what exactly do I buy?

Thank you for helping a fuzzy brained old dolt.

 

[Big Mike]

It doesn't really matter, as long as you keep the lighting consistent. Different types of bulbs will have different light temps/colors. You can adjust your camera to suite just about any light temp, so the type of bulb doesn't matter...but if you start mixing lights with different color temps, then no single WB setting will be correct and you will get weird colors.

 

[Dagwood56]

Thank you Big Mike.

 

[Dwig]

The color temperature of the lamp, as measured in degrees Kelvin, it not terribly important when shooting digital. Digital cameras adjust very well to a wide range.

On the other hand, the Color Rendering Index (CRI) of the lamp is extremely important. In general, you should only use lamps with a CRI of 90 or higher. Tungsten bulbs are excellent. Their CRI is in the 99 range (100 is perfect). Fluorescent lamps area, for the most part, horrid. Their CRIs run in the 60-75 range. The exception are certain special "full spectrum" lamps. These are available from a number of manufacturers and generally have CRI ratings in the 89-91 range. Lamps like the GE Chroma 50 and Sylvania Design 50 are good choices, as are the full spectrum lamps from Ott.

If you use common fluorescent lamps you'll find that most digtal cameras will balance the average color reasonably well. Whites can be made white. What happens is that these lamps don't emit some portions of the spectrum, there are gaps in the spectrum along with some spikes. Subjects whose color relies on a portion of the spectrum missing can't be made to have the correct color regardless of the amount of camera white balance adjustment or post processing.

 

[Don Kondra]

I prefer to not have to worry about a custom WB and use these.

Cheers, Don

 

[Dwig]

I prefer to not have to worry about a custom WB and use these.
Cheers, Don

With a "daylight" balance (e.g. 5500k) and a CRI of 91 they would be a good choice. Also, CFLs produce less heat than an incandescent and would be much safer in a homebuilt softbox. Still, they do produce some heat and you should provide for ventilation and not leave them on in such a softbax unattended.

 

[Don Kondra]

FYI, I have a four head reflector with 45 w CF bulbs. With a nylon diffuser on the head and actually touching the tips of the heads I measured the temperature after a half hour of use. It was just shy of 150 F, a little too warm to actually keep your fingers on them for long but not hot enough to discolor the fabric or burn your fingers with a quick touch

I would not leave any light unattended in an enclosure.....

Cheers, Don

 

[Dagwood56]

Thanks everyone. I'm very alert when it comes to possible fire, so I would be very careful along those lines.