How much light do I need for X amount of space. at DVinfo.net

Deniz Ahmet · January 4th, 2008, 09:38 AM

Looking for a soft flood light so I can basically light up indoor areas for video work. The Interfit Prolite 9 seems the best as it does away with the bulk of softboxes. This is 900w adjustable - What size room can I expect to cover with that kind of power.?

Also , is this light any good anyway? never seen one in action.

thanks

Bill Pryor · January 4th, 2008, 03:53 PM

Lots of these cheaper fluorescents throw out high wattage figures but if you read the fine print they are comparing it to tungsten equivalents. Some sites, for instance, say a 2-bulb fluorescent, like a Caselight, is equivalent to a 500 watt tungsten light. It is, but only if the tungsten light is in a softbox with an equivalent falloff as the fluorescent. I've used small fluorescents to light small spaces...a Lowel Caselight 4 (four 55 watt bulbs) and one or two Caselight 2s (two 55 watt bulbs). You might see if you can find out what the actual fluorescent wattage of that light is. If the 9 means it has 9 bulbs, they probably are in the 30 watt range, I'd guess, but maybe more. If they are 30s, then that would make it similar to a Caselight 4, which is fine for keying in a fairly small space.

Jack Walker · January 4th, 2008, 05:15 PM

It seems the Interfit Pro-Lite 9 is 216 watts:
http://www.bhphotovideo.com/c/produc...e_9_120V_.html

Here are specs on this series of light from the Interfit website:
http://www.interfitphotographic.com/...es/Prolite.php

Marcus Marchesseault · January 4th, 2008, 07:20 PM

Richard Andrewski pointed out that CFL lamps are not quite as efficient as externally ballasted tubes. Also, I think the orientation of the coils diminishes output slightly. You probably need to compare the 216 fluorescent watts of CFLs at noticeablly less than the 220W from a Caselight 4. Also, if I had my choice I would key with a 330W 6-tube light. The extra light and larger physical size would add just the right brightness and softness (larger is softer) to make these fluorescents just about right for most typical situations. I also like the PL-55W tube lights because they somewhat make their own case and don't need the setup hassle of a softbox. It is probably best to use them with some sort of container, but in a pinch they can be moved alone without risking the lamps.

Don't get me wrong. I would use the Prolight 9 anytime but if it was in my budget I would start with a 6-bank of 55W tubes first.

Leo Versola · January 5th, 2008, 02:27 AM

I agree with Marcus and recently placed an order for one of Richard's (Coollights) portable 6-tube flo to replace a 24x36 softbox with an open face as a primary key.

I'm combining it with a couple of the Coollight CDM-150's to make a flexible, lightweight and very portable lighting kit that outputs around 2500 watts of tungsten equivalent while drawing less current and producing less heat than a traditional 650w tungsten lamp.

I'm guess-timating that I should probably be able to cover interiors rooms up to maybe 15x15 given optimum placement options for the lights.

Eric Lagerlof · January 5th, 2008, 08:32 PM

Numerical equivelancies can be a bit misleading. Take a "900 Watt" fluorescent, light a spot on the wall 15 feet away. Then take a 300 watt open face but focusable, tungsten light, like a Lowell Omni, and set it to 'spot'. In terms of brightness, the tungsten will be much brighter-at least on that spot and from that distance. The fluorescent however, will give a larger area better illumination, and less harsh shadows, from much closer.

The bigger fluorescent fixtures should give you a good base level in a 10'x10' up to 15'x15' room if your video camera does modestly well in low light. But if you can, rent a package for a day, including simialr fixtures to what you want to buy, and test it out. (Hopefully no more than 30-50 euros). Or cut a deal with another vdeographer for a day of your labor for a day with their light kit. That way, you can learn from someone with experience and you get to try before you buy without laying out the cash.

Lastly, in your original post, there was no reference to the conditions under which you are lighting, like whether or not you'll have to deal with natural sunlight. And that can change your equatiion quite a bit.

January 4th, 2008, 09:38 AM	#1
Deniz Ahmet Regular Crew Join Date: Oct 2007 Location: LONDON Posts: 178	How much light do I need for X amount of space. Looking for a soft flood light so I can basically light up indoor areas for video work. The Interfit Prolite 9 seems the best as it does away with the bulk of softboxes. This is 900w adjustable - What size room can I expect to cover with that kind of power.? Also , is this light any good anyway? never seen one in action. thanks

January 4th, 2008, 03:53 PM	#2
Bill Pryor Contributor Join Date: Jan 2003 Location: Kansas City, MO Posts: 4,449	Lots of these cheaper fluorescents throw out high wattage figures but if you read the fine print they are comparing it to tungsten equivalents. Some sites, for instance, say a 2-bulb fluorescent, like a Caselight, is equivalent to a 500 watt tungsten light. It is, but only if the tungsten light is in a softbox with an equivalent falloff as the fluorescent. I've used small fluorescents to light small spaces...a Lowel Caselight 4 (four 55 watt bulbs) and one or two Caselight 2s (two 55 watt bulbs). You might see if you can find out what the actual fluorescent wattage of that light is. If the 9 means it has 9 bulbs, they probably are in the 30 watt range, I'd guess, but maybe more. If they are 30s, then that would make it similar to a Caselight 4, which is fine for keying in a fairly small space.

January 4th, 2008, 05:15 PM	#3
Jack Walker Trustee Join Date: Jun 2006 Location: Burbank Posts: 1,811	It seems the Interfit Pro-Lite 9 is 216 watts: http://www.bhphotovideo.com/c/produc...e_9_120V_.html Here are specs on this series of light from the Interfit website: http://www.interfitphotographic.com/...es/Prolite.php

January 4th, 2008, 07:20 PM	#4
Marcus Marchesseault Trustee Join Date: Nov 2005 Location: Honolulu, HI Posts: 1,961	Richard Andrewski pointed out that CFL lamps are not quite as efficient as externally ballasted tubes. Also, I think the orientation of the coils diminishes output slightly. You probably need to compare the 216 fluorescent watts of CFLs at noticeablly less than the 220W from a Caselight 4. Also, if I had my choice I would key with a 330W 6-tube light. The extra light and larger physical size would add just the right brightness and softness (larger is softer) to make these fluorescents just about right for most typical situations. I also like the PL-55W tube lights because they somewhat make their own case and don't need the setup hassle of a softbox. It is probably best to use them with some sort of container, but in a pinch they can be moved alone without risking the lamps. Don't get me wrong. I would use the Prolight 9 anytime but if it was in my budget I would start with a 6-bank of 55W tubes first.

January 5th, 2008, 02:27 AM	#5
Leo Versola Regular Crew Join Date: Aug 2007 Location: San Francisco, CA Posts: 73	I agree with Marcus and recently placed an order for one of Richard's (Coollights) portable 6-tube flo to replace a 24x36 softbox with an open face as a primary key. I'm combining it with a couple of the Coollight CDM-150's to make a flexible, lightweight and very portable lighting kit that outputs around 2500 watts of tungsten equivalent while drawing less current and producing less heat than a traditional 650w tungsten lamp. I'm guess-timating that I should probably be able to cover interiors rooms up to maybe 15x15 given optimum placement options for the lights.

January 5th, 2008, 08:32 PM	#6
Eric Lagerlof Major Player Join Date: Mar 2004 Location: Pacifica, CA Posts: 348	Numerical equivelancies can be a bit misleading. Take a "900 Watt" fluorescent, light a spot on the wall 15 feet away. Then take a 300 watt open face but focusable, tungsten light, like a Lowell Omni, and set it to 'spot'. In terms of brightness, the tungsten will be much brighter-at least on that spot and from that distance. The fluorescent however, will give a larger area better illumination, and less harsh shadows, from much closer. The bigger fluorescent fixtures should give you a good base level in a 10'x10' up to 15'x15' room if your video camera does modestly well in low light. But if you can, rent a package for a day, including simialr fixtures to what you want to buy, and test it out. (Hopefully no more than 30-50 euros). Or cut a deal with another vdeographer for a day of your labor for a day with their light kit. That way, you can learn from someone with experience and you get to try before you buy without laying out the cash. Lastly, in your original post, there was no reference to the conditions under which you are lighting, like whether or not you'll have to deal with natural sunlight. And that can change your equatiion quite a bit.