difference between mole-richardson and Arri lights
Posted 04 May 2010 - 01:50 PM
Posted 04 May 2010 - 03:21 PM
It's good practice to let your lights warm up, then using a color meter you can determine the differences between each light, and gel them accordingly. If you have ever worked on a big production with lots of lights, you might notice a strip of tape on each head with markings like "1/4 CTO", "1/2 minus green", etc. These are usually the designations for which gels to put on the lights so they are all at at the same temperature.
Hope this helps.
Yesterday I did a shoot and mixed and matched some lights, namely an Arri 2k tungsten fresnel and a mole richardson of the same type. I was using them both as the key, bouncing them into a 4x8 piece of white (I didn't have the power for anything bigger and had to really budget). Anyway I noticed that the Mole was very different in colortemp and intensity. The arri was bright and had a nice whitish almost neutral color while the mole was very tungsten-y and not as bright. I had to drop a double scrim in the arri to even it out. Anyone else ever noticed a difference or was there something wrong with the mole light?
Posted 04 May 2010 - 03:51 PM
Posted 04 May 2010 - 05:34 PM
Posted 04 May 2010 - 06:09 PM
Posted 04 May 2010 - 06:17 PM
Were both lights fairly new? I know the age of the bulb affects the color temperature...
Arri's do tend to be more efficient (especially their 1200 HMI pars) but a double is a full stop. For that much of a difference something major must be off. I don't thing the age of the tungsten globe alone could do it alone, they're usually fairly consistent. Several other things can affect the brightness and color temperature as well.
Did you check the basics?
If one light was spotted and one flooded that could easily make a full stop of difference (maybe the mole's mechanism was jammed)
Is it possible that one of the lights was on a dimmer?
Did you check the actual globes? Sometimes people put smaller globes in units for various reasons.
Dust can have a huge impact, if the reflector and the lens are dusty it can significantly reduce your output and warm the color temp, probably not a full stop though...
The size of the light matters - the big studio units have bigger lenses and reflectors and so put out more light, the smaller location lights (baby's) put out less. probably not a full stop though...
I have seen a severely damaged globe act inconsistently. After a hard knock that causes some of the filaments to cross or break the globe can burn much brighter or dimmer than usual (usually for a short time before failing)
Posted 05 May 2010 - 09:16 AM
Posted 05 May 2010 - 01:47 PM
all this can affect a lamps output.
also the reflector could have been out of focus. the position of the reflector in reference to the filament.
Posted 05 May 2010 - 04:30 PM
Posted 05 May 2010 - 04:40 PM
Posted 05 May 2010 - 05:27 PM
Posted 05 May 2010 - 08:07 PM
I'm most familar with the above principle in the HPL series bulbs my Source Four's use. I can get 120 volt HPL575WX's that actually have 130 or so volt filaments and will run 2,000 hours and put out 12,360 lumens at 3050K color temperature. I use them on theatre productions where it's nice to have bulbs that will last for a long run. But obviously I have to design for the reduced lumens per fixture.
But for movie and video work I use 120 volt HPL750's that are rated at 300 hours, put out 21900 lumens and have a 3250K CT. I have some true 120 volt HPL575's that last 300 hours, put out 16520 lumens, and have a 3250K CT.
Bottom line is I suspect your Mole might have some type of long life bulb in it. See if you can still read the ratings printed on the bulb. If it has an ANSI number it will be easy to research what you've got. http://www.bulbconnection.com is a good place to research bulbs.
Posted 06 May 2010 - 08:59 AM
Posted 06 May 2010 - 10:31 AM