|
Reading through this interesting thread a couple of things ocurred to me -- just my 2 cents.
Using household dimmers on large wattages is problematic. If you run these solid-state devices (opposed to resistive dimmers) close to the maximum rating they get hot and the heat will break them over time (you'll note in some installation instructions that you have to reduce the load if you cut the AL heat sink when ganging a number of dimmers in the same space). The unstated assumption is that most household applications don't reach the maximum rating of the dimmer and that there is an allowed overhead -- in most installations of a couple hundred watts under the maximum load (for example the average household chandelier which is a typical application is often well under 500w).
Years ago I was involved with a little theatre that used household dimmers for lighting control. We were replacing them all the time because we were running them at max rating all the time. So what can seem inexpensive at first and be expensive in practice. Theatircal SCR dimmers are expensive because they have to stand up to such abuse.
Dimming also introduces the color temp issue. Video cameras are engineered to produce accurate color reproduction when illuminated with the standard 3,200K, although some cameras can compensate a bit on either side (white balance), and many have a "daylight" setting (5,600K or so). If you want consistent color shot-to shot, you need consistent color temp. And this will work if you are sure the dimmer is set at exactly the same place each time -- but then the low-cost dimmers "drift" as they get hot and as they wear out the settings change. What was 50% last week won't be this week.
In any case, the color temp of the tungsten lamps you'll find at home depot is usually 2,950K (check the manufactuers web sites) or more yellow than the 3,200K standard. There are some 3,200K floursescents sold for retail display use (by GE and others I think).
One other thing. The intensity of the light is really only one aspect of its look and feel. Changing intensity is not going to change the quality of the light as much as one might think in terms of hard vs. softer looks. What you may really be after is the look of an instrument you can focus hard to soft (i.e. a fresnel). Changing intensity is not the same thing as changing focus.
Before using dimmers I'd suggest three other things to experiement with. First, move the lights back or closer to change intensity. The inverse square law is your friend here: doubling the distance halfs the intensity. Second try ND filters on your lens to reduce the effective intensity. Third, mix the first two. I think the results will be more consistent and less expensive in the long run than messing with household dimmers. Unless you need a sudden brightening effect, I don't see a good reason to use them.
|