double fixture china balls

Sherwin Akbarzadeh · June 4, 2012

Hi All,

I'm making up some 30 inch china balls for an upcoming project. I'm looking into bulbs and with heat/safety in mind I am considering compact fluorescents. There are a lot of open windows in my locations that I cant afford to block and replace so I want something that will match daylight. The Alzo bulbs (http://www.alzodigital.com/online_store/light_bulbs_compact_fluorescent_video-lux.htm) claim 5600K but they get mixed reviews - some people measure them at 6100K.

I was going to put a Y-adapter socket in my china balls so that I could potentially run two 85 watt CFLs if i really need the light. But if these bulbs are really 6100K, I could run an 85 watt in one socket and warm it up a bit with a 27 or 45 watt tungsten balanced bulb in the other socket. The question is, does the light bounce around inside the china ball enough to mix these two color seamlessly? If so, what is the maths for calculating the resulting color temperature from these combinations?

Appreciate any feedback on these questions or anything else that strikes you.

David G. Smith · June 5, 2012

Hi All,

I'm making up some 30 inch china balls for an upcoming project. I'm looking into bulbs and with heat/safety in mind I am considering compact fluorescents. There are a lot of open windows in my locations that I cant afford to block and replace so I want something that will match daylight. The Alzo bulbs (http://www.alzodigital.com/online_store/light_bulbs_compact_fluorescent_video-lux.htm) claim 5600K but they get mixed reviews - some people measure them at 6100K.

I was going to put a Y-adapter socket in my china balls so that I could potentially run two 85 watt CFLs if i really need the light. But if these bulbs are really 6100K, I could run an 85 watt in one socket and warm it up a bit with a 27 or 45 watt tungsten balanced bulb in the other socket. The question is, does the light bounce around inside the china ball enough to mix these two color seamlessly? If so, what is the maths for calculating the resulting color temperature from these combinations?

Appreciate any feedback on these questions or anything else that strikes you.

I bought some of those Alzo 27 watt daylight bulbs and I have to say that I was kind of disappointed in them. I do think that they are pretty close to 5600K, but they also have a pretty prominent green spike. You will need to add at least some 1/8 or 1/4 minus green to counter that. (To your tastes of course. From my tests, 1/8 still leaves a tiny bit of green and 1/8 is too magenta for my tastes. I would like to be able to stack a 1/16 on a 1/8 and see how that looks, but I can't find 1/16 minus green).

My biggest issue is the light intensity. Don't be fooled by that "Equivalent light output" hype about the CFLs. I did photometric testing of the Alzo 27 watt CFL, directly out of a reflector scoop light, and got 30 footcandles (FC) at 5 feet (f2.8 @ 500 ISO*), 7FC at 10 feet (f1.4 @ 500 ISO) and <5FC at 15 feet (>f1.4 at 500 ISO). I tested a 100 watt soft white incandescent bulb in the same fixture and got 50FC at 5 feet (F4 @ 500 ISO), 15FC at 10 feet (F2.0 @ 500 ISO) and 5FC at 15 feet (f1.4 @ 500 ISO). Even doubling up these bulbs in a china ball may not be enough light to really do much when trying to match to daylight from windows.

*F-stop settings are closest match from analog meter readings.

Edited June 5, 2012 by David G. Smith

David G. Smith · June 5, 2012

Oops, in "...From my tests, 1/8 still leaves a tiny bit of green and 1/8 is too magenta for my tastes...", I meant to say, "1/8 still leaves a tiny bit of green and 1/4 is too magenta for my tastes...".

Sherwin Akbarzadeh · June 6, 2012

Thanks for sharing that David.

Interesting test results between incandescent and CFL. I'll get some incandescents or halogens for my tungsten scenes. I was attracted to the CFLs for heat and safety reasons but everyone seems to be happy with halogens in their china balls.

For the daylight stuff, I guess I'll stick to the CFLS and look at some 1/8 minus green. I don't see what choice I have within my budget range.

Thanks.

David G. Smith · June 6, 2012

Oh yeah, I can understand budget constraints, that is for sure. For halogen lights, I found these 250 watt bulbs on eBay, from this seller (Linked seller just in case the item description times out). They seem to me to be the same that are sold at Filmtools for a much higher price. I think they would work well in china balls.

I tested the photometrics of those halogen, in a reflector scoop like noted above, and they gave 320 FC at 5 feet (f8/11 split at 500 ISO), 70FC at 10 feet (f4/5.6 split at 500 ISO), 30FC at 15 feet (f2.8 at 500 ISO) 15FC at 20 feet (f2.0 at 500 ISO), 10 FC at 25 feet (f1.4/2.0 split at 500 ISO), and 7FC at 30 feet (f1.4 at 500 ISO).

They can be screwed into any standard medium base (E-26) socket (rated for the wattage), and are very handy.

Sherwin Akbarzadeh · June 7, 2012

Thanks David.

I was about to get the film tools ones but if the ebay ones tested ok then why not. Kinda wish i could find the same in 500w though. I'd get these if it weren't a paper lantern fire hazard: http://www.filmtools.com/rps-studio-650w-3200k-quartz-halogen-bulb-e-27-socket-adapter-034447041494.html

Sherwin Akbarzadeh · June 7, 2012

think it'd be too hot to stick 2 of those 250w halogens in a 30' china ball using one of these? http://www.amazon.com/Leviton-128-I-660-Watt-Light-Socket-Adapter/dp/B001ATG0JU/ref=sr_1_1?ie=UTF8&qid=1339048731&sr=8-1

David G. Smith · June 7, 2012

You know, a 30 inch DIAMETER china ball seems to me to be big enough to accommodate two of those 250 watt halogens, but I would definitely test it out before I used it on a shoot. I would set up a rig like that outside and let it cook off for a while to see how hot they get.