Lowel Rifa Light
Has anyone had any trouble with the lamps in the Lowel Rifa Light? I have a an EX66 - a superb piece of kit - and I use a 650 watt lamp for 240v AC UK mains. These are rated for 300 hours, but so far the best I've had is about six hours. I use the Rifa for location work and only try to move it when the lamp cools. But these lamps stay hot for a long time and it is supposed to be portable, and time is money. The lamps are not easy to get out to replace when hot so I've ordered a new THX1000 holder which I shall lamp up ready to exchange the whole unit (with a suitable glove)
I seem to lose the lamp on fire-up, rather than after use, so I have introduced a dimmer into the circuit, plus a mains spike smoother which seems to work so far. Is there a problem in the in-line switch I need to know about?
Pearldrop Video Productions
Long-time Rifa user/fan, and this has never happened to me like what you describe. If you say you're not moving or jarring the hot light, I have to believe you, my next guess then would be you got a bad batch of lamps or your power is dirty somehow. Though you say you've taken steps regarding the power already.
You're not in the US, I take it, so maybe it's a hertz thing. All I can say is we use Rifas weekly for hours at a time, and I think I've changed ONE lamp in as many years. Our guys are constantly putting the nomex fabric of the Rifa's to the test by wrapping and putting the things away still a bit warm. They ended up charring a spot into one of them that way, but it still works fine. Ours mostly get worn in the little umbrella rib tips, and of course, if you fold the diffuser instead of rolling it up, you introduce splits in the material, so don't ever fold up the diffusers.
If you can swing the expense, I recommend sending the old Rifas in to Lowel for their 2-head conversion upgrade, which enables you to switch between a halogen-based lamp and a flo-based one in the field, very neat trick and it enables the Rifa to be used where power or heat a big concern.
Meanwhile, I'd try a different brand or at least production batch of lamps, and put a meter on the power supply you're using to see if surges or something are affecting lamp life. Let us know if you figure it out.
Thanks for your ideas Mark. I was interested to note that your lamp replacement is rare, so we have a problem somewhere. Yes, we are in the UK using 240V AC mains at 50 hertz, but the lamps are correctly rated for our supply. I've sent one of the lamps back to the manufacturer to see if we just had a bad batch and I'm waiting for the report. I'm also getting a new THX1000 lamphead this week to act as a quick replacement in the field - this is to get over the hot lamp replacement problem and the waiting time for it to cool on a busy shoot. I think what I'll do is put this lamphead into the Rifa to see if the old one was where the problem lay.
As you say, it's easy to burn the fabric of the Rifa if you strike to soon. I've made a sock out of a plumber's protective mat (bought from our local DIY store) to go over the frame of the THX1000 holder. I stitched this into a cylinder so it fits neatly over the wire frame without making contact with the lamp. I still let the lamp cool a lot before I use it, but it does give the extra bit of protection. I'm sure this is not the reason the lamps are blowing because we had the problem before I introduced it. Incidentally, we take all the usual precautions in not touching the lamps on installation with fingers - we use surgical gloves to hold the lamp, which is certainly fiddly to get into the socket.
The last thing I'm trying is to get a replacement for the switch section of the supply lead - it may be a faulty switch. I'll let you know howwe get on.
Pearldrop Video Productions
I, too, have used these lights here in the US for years and have been very pleased with their performance. It is rare that I change the lamps. When I worked more with students, however, I did have to caution them to handle the lamps with cloth instead of greasy fingers which might shorten lamp life. And they might also not seat the lamp into the socket, which might not bode well for lamp life.
I also use smaller 250w Lowel Rifa 44 lights, and have found those small lamps are easily prone to destruction if handled roughly. But the 650 and 750 lamps I used with the larger Rifa's have weathered very well.
For all the Lowel lights I use, I seem to replace the swithes a lot. I guess you can't have everything.
I'm on year number 6 with the original bulb in My Rifa light. I use it a lot, and probably don't wait long enough to pack it up and move to the next set-up. I really need to do the retro-fit to CFLs, as a lot of my projects deal with energy efficiency. Don't fear the Rifa! (More cowbell)