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Question about watt-seconds and light output capability

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Alex Ethridge

Alex Ethridge

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Let's say I wanted to light a room 30x30 (feet), off-white walls, white ten-foot ceilings, medium gray floor with 30 or so people milling about, dancing or whatever else, and I wanted to do it with four lights aimed at the walls or ceilings to give images a wide open, almost daylight look.

What WS rating on each light do you think will do it.

Yes, I know WS is input but that's the way they're rated (or were in the days of film). If power ratings are different in the digital age, please set me straight.
 
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That, in part, depends on what ISO you are willing to use and what aperture.
 
Alex Ethridge said:
Let's say I wanted to light a room 30x30 (feet), off-white walls, white ten-foot ceilings, medium gray floor with 30 or so people milling about, dancing or whatever else, and I wanted to do it with four lights aimed at the walls or ceilings to give images a wide open, almost daylight look.

What WS rating on each light do you think will do it.

Yes, I know WS is input but that's the way they're rated (or were in the days of film). If power ratings are different in the digital age, please set me straight.
Click to expand...
It's an interesting perception of a lighting problem and certainly off-track with regard to how to solve it.

Honestly, you should know that there is no formula for evaluating light source WS output power for bounced light, except to combine separate meter readings from each reflected source. It has less to do with the WS power output directly calculated than the metered exposure of reflected light sources. Albeit as you setup, you can run some tests adjusting WS output from the lights independently of each other to hone the results you desire and visualize.

For calculations when you know the exposure for one light, you can take individual incident light meter readings and use the example of multiple light source f-stop combination ...

SQRT(f1^2 + f2^2 ...) = fs

Then use the Reciprocity Law to make Exposure Adjustments for specific Aperture, Shutter Speed and ISO values.

But if you are setting up Continuous Lighting, just do a reflected meter reading from the framed scene area and set Exposure as desired from that reading.

When it comes to the room dimensions, you are of course, interested in fade-off. But you need not go bothering with the Inverse Square Law in that. Light intensity from the source is already altered after bouncing it from a wall or ceiling, both by fade-off and by the nature of the bounce surfaces, followed afterwards again by fade-off. Just meter the light and adjust the power outputs to get what you find acceptable.
 
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flyinglentris said:
Alex Ethridge said:
Let's say I wanted to light a room 30x30 (feet), off-white walls, white ten-foot ceilings, medium gray floor with 30 or so people milling about, dancing or whatever else, and I wanted to do it with four lights aimed at the walls or ceilings to give images a wide open, almost daylight look.

What WS rating on each light do you think will do it.

Yes, I know WS is input but that's the way they're rated (or were in the days of film). If power ratings are different in the digital age, please set me straight.
Click to expand...
It's an interesting perception of a lighting problem and certainly off-track with regard to how to solve it.

Honestly, you should know that there is no formula for evaluating light source WS output power for bounced light, except to combine separate meter readings from each reflected source. It has less to do with the WS power output directly calculated than the metered exposure of reflected light sources. Albeit as you setup, you can run some tests adjusting WS output from the lights independently of each other to hone the results you desire and visualize.

For calculations when you know the exposure for one light, you can take individual incident light meter readings and use the example of multiple light source f-stop combination ...

SQRT(f1^2 + f2^2 ...) = fs

Then use the Reciprocity Law to make Exposure Adjustments for specific Aperture, Shutter Speed and ISO values.

But if you are setting up Continuous Lighting, just do a reflected meter reading from the framed scene area and set Exposure as desired from that reading.
Click to expand...
I know how to use lights, a flash meter and make calculations but there are no lighting suppliers in my area and I don't have anything to experiment with. If I did, I would not have to ask this question.

When I make a purchase, I'll be stuck with whatever I get so I'm trying to get as much information as I can to determine how much power I'll need and what the approximate cost is.
 
Alex Ethridge said:
When I make a purchase, I'll be stuck with whatever I get so I'm trying to get as much information as I can to determine how much power I'll need and what the approximate cost is.
Click to expand...
So, it would not take a lot at those camera settings. My next question is what else would they be used for, if anything? You can dial lights down, or lower or use an ND filter when needed than it is to add light when needed (Raising ISO is not always the answer).
 
antares103 said:
Alex Ethridge said:
When I make a purchase, I'll be stuck with whatever I get so I'm trying to get as much information as I can to determine how much power I'll need and what the approximate cost is.
Click to expand...
So, it would not take a lot at those camera settings. My next question is what else would they be used for, if anything? You can dial lights down, or lower or use an ND filter when needed than it is to add light when needed (Raising ISO is not always the answer).
Click to expand...
Primarily lighting an auditorium, church interior, wedding reception hall. I figure if I have four lights of sufficient power, I could use one, two three, or all four to light most any venue in a manner of my chosen style, which I mentioned in the initial post, bright and airy.

Having more than I need in most situations is my idea and being able to dial them down as needed. Too little power and I'm in trouble, too much and I can dial them down.

I don't want to burn the paint off the walls but I do want sufficient light.

Problem is, I've never used studio lighting and have no idea about the necessary power ratings.

Maybe there are some lighting suppliers in Atlanta (about 150 miles) but I'm trying to nail down as much information as possible to target things better if/when I make the trip.
 
Alex Ethridge said:
I know how to use lights, a flash meter and make calculations but there are no lighting suppliers in my area and I don't have anything to experiment with. If I did, I would not have to ask this question.

When I make a purchase, I'll be stuck with whatever I get so I'm trying to get as much information as I can to determine how much power I'll need and what the approximate cost is.
Click to expand...
Ah, that's different than what I thought I had read in your original post.

I would get light units at least 500 WS. The next step up is 1000 WS and more expensive. When you get into those power ranges, you generally don't want battery power, but outlet power sourced lights. Though you can probably get away with large lithium battery power for 500Ws.

I would think that a 30x30' space could be handled by 500W light units, especially when you are putting 4 of them into play. You can always use Throw Reflectors on the light units to project the light to greater distances - although, the beams will be narrowed.

Larger spaces may require more power, 1000 WS.

You can also use the technique of banking light units to increase area coverage.

I use Buff Einstein 640 WS lights. But some members here will likely recommend other brands which have different virtues. For example the Buff light units do not allow TTL metering. Other brands do. It's your choice with regard to the brand.

I also have a Buff Digibee DB800 light unit which is 800 WS.

--
"If you are among those who believe that it has all been done already and nothing new can be achieved, you've murdered your own artistry before ever letting it live. You abort it in its fetal state. There is much that has yet to be spoken in art and composition and it grows with the passage of time. Evolving technologies, world environments and ideologies all drive change in thoughts, passion and expression. There is no way that it can all ever be done already. And therein lies the venue for the creative artist, a venue that is as diverse as the universe is unmapped and unexplored." - Quote from FlyingLentris
~
flyinglentris in LLOMA
 
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flyinglentris said:
Alex Ethridge said:
I know how to use lights, a flash meter and make calculations but there are no lighting suppliers in my area and I don't have anything to experiment with. If I did, I would not have to ask this question.

When I make a purchase, I'll be stuck with whatever I get so I'm trying to get as much information as I can to determine how much power I'll need and what the approximate cost is.
Click to expand...
Ah, that's different than what I thought I had read in your original post.

I would get light units at least 500 WS. The next step up is 1000 WS and more expensive. When you get into those power ranges, you generally don't want battery power, but outlet power sourced lights. Though you can probably get away with large lithium battery power for 500Ws.

I would think that a 30x30' space could be handled by 500W light units, especially when you are putting 4 of them into play. You can always use Throw Reflectors on the light units to project the light to greater distances - although, the beams will be narrowed.

Larger spaces may require more power, 1000 WS.

You can also use the technique of banking light units to increase area coverage.

I use Buff Einstein 640 WS lights. But some members here will likely recommend other brands which have different virtues. For example the Buff light units do not allow TTL metering. Other brands do. It's your choice with regard to the brand.

I also have a Buff Digibee DB800 light unit which is 800 WS.
Click to expand...
Sounds good. Looks like if I go with four 1K-WS lights, I'll be well prepared. I'll probably start with two and build on that. Now I need to explore TTL metering, brands and other features.

I would also want recycle times around 1.5 seconds or less.
 
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Alex Ethridge said:
Let's say I wanted to light a room 30x30 (feet), off-white walls, white ten-foot ceilings, medium gray floor with 30 or so people milling about, dancing or whatever else, and I wanted to do it with four lights aimed at the walls or ceilings to give images a wide open, almost daylight look.
Click to expand...
That's my routine for wide-area fill in my studio which is a white box of 1/4 your room's volume. I can get full exposure at 100 ISO, f/5.6 with 1000Ws from a bare bulb in one corner, shielding the direct light with a foamcore panel. You could achieve fill similar to my image below with 500Ws in two corners provided the walls are white or off-white. Using a diffuser panel in one corner gives some free directionality.

matt006b.png


Uncropped test shot above has active key lighting from a Magnum dish but note the fill is everywhere and nicely uniform.

--
Canon, Nikon, Contax RTS, Leica M, Sony, Profoto
 
Rico Tudor said:
Alex Ethridge said:
Let's say I wanted to light a room 30x30 (feet), off-white walls, white ten-foot ceilings, medium gray floor with 30 or so people milling about, dancing or whatever else, and I wanted to do it with four lights aimed at the walls or ceilings to give images a wide open, almost daylight look.
Click to expand...
That's my routine for wide-area fill in my studio which is a white box of 1/4 your room's volume. I can get full exposure at 100 ISO, f/5.6 with 1000Ws from a bare bulb in one corner, shielding the direct light with a foamcore panel. You could achieve fill similar to my image below with 500Ws in two corners provided the walls are white or off-white. Using a diffuser panel in one corner gives some free directionality.

matt006b.png


Uncropped test shot above has active key lighting from a Magnum dish but note the fill is everywhere and nicely uniform.
Click to expand...
Thanks, this is more of the very kind of information that helps me. Features are easy to compare once I have a list of them but without experience with studio lighting, power was something I was in the dark about (no pun intended). :-)
 
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4 x 400 watt-second lights with standard reflectors, one in each corner pointing at the ceiling should do it.

--
Ellis Vener
To see my work please visit http://www.ellisvener.com
Or on instagram @therealellisv
 
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Since you've decided you want 1000 w/s flash units, go to the Profoto web site and look for the Daniel Norton article about photographing a model named Marissa Roper.

And look up On Set with Daniel Norton on Youtube, and you'll see him using studio flash.

Go to PaulCBuff.com and go to the INFO section, and look down the menu for various topics.

Here's something to think about: imagine a chess board and pretend it is a 30 x 30 room. Imagine the chess pieces standing all over the board, and facing in many different directions.

In a real room, how would you place a flash pointed at a face 10 feet from a wall and another face 20 feet from a wall so that they are lit equally?

Good luck.

BAK
 
Between bright flashes of light when you click the shutter, (recycling in 1.5 seconds) what's the room like?

Will the people there be whapalozzaled by eye-hurting bursts? I remember shooting a wedding where the bride told me of being a guest at a wedding where the photographer bounced four 2400 w/s power packs worth of light off the ceiling, over and over.

(Apparently the pictures were all overexposed, too)

About recycling times.

1/ yes, I know you do not plan to click click click constantly.

2/ if you see a recycling time for a plug-in monolight listed as 1.5 seconds, it will be implied that 1.5 is for full power. 1/2 poer, 1/4 power, etc will be shorter.

Finally, several good arguments can be made for more lower-powered flash units instead of fewer high-power units.

BAK
 
flyinglentris said:
flyinglentris said:
...
Click to expand...
I also have a Buff Digibee DB800 light unit which is 800 WS.
Click to expand...
The DB800 is a good light, but has only 320Ws of power.

I'm a big fan of the Einstein lights. I think they are a good choice, and can be set for anywhere from 2.5Ws to 640Ws.

One nice thing about the Einsteins is that they are designed to be used with normal power. You should be able to plug two of them into the same circuit, and they shouldn't blow the breaker. Lights that recycle faster than the Einsteins draw more power when recycling, and are more likely to trip circuit breakers.

If you need more power than 640Ws, I suspect you are better off with more lights, rather than higher power lights. More lights make it easier to get a more even distribution throughout the room.

Buff sells a lithium battery/inverter system. With an Einstein at full power, it slows the recharge time down to about 4.3 seconds. You can put more than one Einstein on a battery pack, but I don't recommend it for event shooting,. Multiple lights per pack take even longer to recharge.
 
Position your bare bulb lights without reflectors so that they are aimed at the corner where it meets the ceiling. Having them a couple of feet from the corner should be fine.

If you use light stands block them off to make sure that nobody can bump into them and knock them over.

If the ceiling is a drop ceiling then these are a much safer way to mount your lights. Kupro makes one with a longer pin.

Adorama - Alzo Digital Suspended Drop Ceiling Photo Video Light Mount Kit

Adorama - Kupo Baby Drop Ceiling Adapter with 5/8" Stud

You will not get even lighting and it will be top down lighting so you will have shadowed eye sockets.

You can walk around the venue with your flash meter just in front of your chin and take readings, and use pieces of different colors of tape to show you the different exposures.

Alternatively use a TTL flash on-camera and use Flash Exposure Compensation to turn the flash into a fill flash. You want to fill in the shadows in the eye sockets yet keep the surroundings fairly well exposed.
 
Alex Ethridge said:
Let's say I wanted to light a room 30x30 (feet), off-white walls, white ten-foot ceilings, medium gray floor with 30 or so people milling about, dancing or whatever else, and I wanted to do it with four lights aimed at the walls or ceilings to give images a wide open, almost daylight look.

What WS rating on each light do you think will do it.

Yes, I know WS is input but that's the way they're rated (or were in the days of film). If power ratings are different in the digital age, please set me straight.
Click to expand...
You seem to have had quite a lot of advice on this but I haven't seen anybody ask you an important question. Do you need mains or battery powered lights?

Mains lights are cheaper, can be more powerful (1200Ws or so), generally recycle quickly, and will keep going all night. However you do need to run cables to them and having one in each corner of a room pretty much guarantees that at least one of them will have a long cable run. In a room full of dancing people you will have to be very careful how you run the cables and some venues are rather touchy about having trip hazards.

Battery lights are considerably more expensive. Have limited power capacity (600Ws tops) and limited battery capacity (typically 300-400 full power pops). They have the advantage of being cable free and generally easier to transport and quicker to set up.
 
BAK said:
Since you've decided you want 1000 w/s flash units, go to the Profoto web site and look for the Daniel Norton article about photographing a model named Marissa Roper.

And look up On Set with Daniel Norton on Youtube, and you'll see him using studio flash.

Go to PaulCBuff.com and go to the INFO section, and look down the menu for various topics.
Click to expand...
Thanks, there's lots to digest there. I've already seen a few of those and will be looking at more later.
BAK said:
Here's something to think about: imagine a chess board and pretend it is a 30 x 30 room. Imagine the chess pieces standing all over the board, and facing in many different directions.
Click to expand...
I know there are TTL monolites and that is one of the types I'm thinking about. Of course without any experience with them, I don't know how well the TTL feature works at all apertures or that many TTL units work well together. I heard there may be one or more brands (Godox for one) that over/under-exposure was wild at wide apertures.
BAK said:
In a real room, how would you place a flash pointed at a face 10 feet from a wall and another face 20 feet from a wall so that they are lit equally?
Good luck.
Click to expand...
With remotes, I can turn on/off various monolites based on the direction the camera is aimed. Also, I intend to have on-camera fill on hand to see how that works, then an assistant will carry an accent lite placed either behind the subject with subject blocking his/her view from the lens or just outside the frame.

Of course none of this is carved in stone and this is a scenario I will grow into slowly. Then again, I may never carry out this plan at all. I'm thinking about how many events/weddings I would have to shoot to pay for $10K of equipment and at my age how many weddings I'm willing to do in a month.

It's pie in the sky right now.
BAK said:
BAK
Click to expand...
 
BAK said:
Between bright flashes of light when you click the shutter, (recycling in 1.5 seconds) what's the room like?

Will the people there be whapalozzaled by eye-hurting bursts?
Click to expand...
Maybe TTL monolites and wider apertures will help with that?
BAK said:
I remember shooting a wedding where the bride told me of being a guest at a wedding where the photographer bounced four 2400 w/s power packs worth of light off the ceiling, over and over.

(Apparently the pictures were all overexposed, too)

About recycling times.

1/ yes, I know you do not plan to click click click constantly.

2/ if you see a recycling time for a plug-in monolight listed as 1.5 seconds, it will be implied that 1.5 is for full power. 1/2 poer, 1/4 power, etc will be shorter.

Finally, several good arguments can be made for more lower-powered flash units instead of fewer high-power units.
Click to expand...
Yes, I'm thinking of that, too, but more lights means more set-up and take-down time and more lights to worry about getting kicked over.
BAK said:
BAK
Click to expand...
 
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