If you hook a dimmer up to a halogen, won't the color temperature change as you increase the brightness?

And if yes, how do dimmable camera mounted lights work?
(I'd like to try and rig up my own dimmer to save $$$)

Anyone have any "bright" ideas?

Yes, color temperature will change.

Not to rain on your parade or anything, but I think the time and resources you'll spend on trying to "roll your own" will exceed the cost of just buying a good one to begin with. That's been my experience, anyway.

Do you mean, how well do they work or what is the system used?

Speaking for my Frezzi Mini-Fill with dimmer, I can tell you that it works quite well. The dimmer is something I didn't think of at first, like "how can there be any such thing as too much light, I want MORE light" but Ed at Frezzi talked me into it with his most emphatic recommendation. And I am glad he did. It makes it so much more of a pleasure to use, since I can "roll" in enough light and not make the talent (usually not professional entertainers, just ordinary non-media people) yell "Whoa!" and squint and hold their hand up in front of their face, which we all have too much footage of. Actually, if I need to get to full brightness, I can ramp it up gently so they get acclimated and don't exhibit that shock reaction.

As for what Frezzi uses, "an advanced pulse width modulation circuit allows instant adjustment of the light intensity while minimizing color change and conserving power." It's a lot more than a simple rheostat which works by varying the voltage (which would be bad because that would really play with your color temp).

Not cheap, but worth it for a light that was developed for the first Mount Everest climb (!!!!) and is used by every broadcasting company in the world. You will not ever have to buy another camera-top light again.

Mike...after putting in the good word for me with Frezzi and helping to get the ball rolling on my never-ending order, and now helping out fargograf...I think Frezzi should appoint/annoint you as the "Grand Ambassador de Frezzi!"

I'll volunteer as your attaché since I love my mini dimmer fill, too.

Thanks John. Thanks also for the detailed answer to Andrew in the other thread. I added a little more of my $.02 there as the non-stop Frezzi ambassador and cheerleader.