How much strobe power do I need?

I'm having a hard time getting my head around all I read regarding strobe power. Example, quantifying the light output, i.e., watt seconds. It seems like having more light available would always be better, but what is enough? What is not enough? In a small studio I would imagine that I could get away with 160was and probably be fine. What if I wanted to take strobes outside, or to something like a gym and shoot a basketball game... 1000ws minimum? Or would 320ws serve the purpose? Is there a site that lists what amount of power is recommended for different situations? Anyone have lots of experience with this?

I've been warned that subjective questions like this make it difficult to answer but I'm really just looking for some plain common sense advice.

320ws is not a strong light. Even in a small studio 160ws is weak, at least for a main light, I'd be surprised if you were allowed to place truly strong lighting on a basketball game.The players might object.

Get yourself two 400's that way if one isn't enough you always have a second, and if two is too much you can pull one back. That's what I plan on starting out with when I get lighting Great for studio lighting and outdoor use

Just depends on what you're doing. If your shooting L/F product then you can never have enough power. For that speedotron blackline 4803s.

Single and couple portraits then ya really don't need allot, groups ya need more. I have white lightning 1200s and for single and couples they're over kill but its nice to have the juice when doing groups.

Phil Light wrote in post #6065422
I'm having a hard time getting my head around all I read regarding strobe power.

I will help you out...

The very first thing you need to know before you go down this path is the following:

1. Desired ISO, aperture, and subject distance (lights from subject distance) you want to shoot at.

2. Desired modifiers (60" umbrella, 50x50 softboxes, 8ft octaboxes)

3. Will you be shooting outside?

Work very hard at figuring out #1 above or we can't help you. But to give you something to chew on I will make an assumption.

** ISO 100, f8, and lights 15 feet from subject indoor studio using two 60" umbrellas and one bare kicker **

Ok that is what your going to be doing... okay I can offer you the following advice. Get two AlienBee B800 and one AlienBee B400.

Next question!

pcunite wrote in post #6066112
...The very first thing you need to know before you go down this path is the following:

1. Desired ISO, aperture, and subject distance (lights from subject distance) you want to shoot at...

I appreciate the responses so far. My primary concern is lighting a gym during a game, not studio. I know if I decide to do studio work I can always dial the light down so I'm not really concerned about the low end. I'm just wondering if someone has experience with this. This actually might have been a good question to post in the sports section. Anyway, here's what I'm thinking:

a. ISO - Of course my preference would be 100 but that's not realistic. I'd prefer not to go above 400 though if possible.

b. Aperture - f/2.8 - f/5.6 typically

c. Subject distance - Tricky one. All gyms are different. On average the light will probably have to be 25 - 40 feet from the players and most likely bounced off the ceiling to avoid blinding a player who might happen to be looking in that direction. And yes, sports shooters use strobes in gyms all the time. It's generally up to the coach or AD as to whether that's allowed.

Just a simple reflector. No reason for modifiers for this

Very possibly

....** ISO 100, f8, and lights 15 feet from subject indoor studio using two 60" umbrellas and one bare kicker **

Ok that is what your going to be doing... okay I can offer you the following advice. Get two AlienBee B800 and one AlienBee B400.

Next question!

No, not really. That's not at all what I'll be doing. I've looked at the AlienBee systems and they seem underpowered for the price. The colors are nice though.

jr_senator wrote in post #6065627
320ws is not a strong light. Even in a small studio 160ws is weak, at least for a main light, I'd be surprised if you were allowed to place truly strong lighting on a basketball game.The players might object.

This is a blanket statement that I don't find to be true at all. I own a full functioning small studio and 320ws was too much power for my main and other subject area lighting. It let me shoot from f/5.6 to f/16 but without using gels or ND's I could never shoot at f/4, much less f/2.8.

I use 200ws strobes and find them to work very nicely and 160ws would also do the job well.

In small studios we don't tend to spread out and have out main light 8 or 10 feet from the subject. So when we want a large soft light source and isolation from the background we place the main light source 2 or 3 feet from the subject. With too much power it's very limiting.

TMR Design wrote in post #6066379
This is a blanket statement that I don't find to be true at all. I own a full functioning small studio and 320ws was too much power for my main and other subject area lighting. It let me shoot from f/5.6 to f/16 but without using gels or ND's I could never shoot at f/4, much less f/2.8.

I use 200ws strobes and find them to work very nicely and 160ws would also do the job well.

In small studios we don't tend to spread out and have out main light 8 or 10 feet from the subject. So when we want a large soft light source and isolation from the background we place the main light source 2 or 3 feet from the subject. With too much power it's very limiting.

I must admit I don't recall taking a portrait where the main lighting was 2-3' from the subject and I'm not sure this is common practice. I would consider my studio area small but the lighting is 7-10 (sometimes 12) feet away from the subject. I don't know what kind of lights you have but evidently you can't adjust the output.

I agree with Robert, sometimes 160 w-s can be too much! Let Alien Bee web site be your guide...B400 unit has 160 w-s true rating. According to Buff, with 7" reflector it has f/11 + 0.2EV @ 10' or a Guide Number of about 120; f/4 reaches to 30'. In a studio, you would shoot at about 10' at most, forcing f/11 + 0.2EV. Dialed down to minimum power, the B400 still requires f/2.8 from a single light at a distance that assumes a roomy shooting area!
If you shoot at ISO 1600 on the Basketball court, the GN becomes 480; f/4 reaches to 120' with the 160 w-s B400 (actually a bit less because of high ceilings etc. that reduce the effective power output from manufacturer's rating!

jr_senator wrote in post #6066590
I must admit I don't recall taking a portrait where the main lighting was 2-3' from the subject and I'm not sure this is common practice. I would consider my studio area small but the lighting is 7-10 (sometimes 12) feet away from the subject. I don't know what kind of lights you have but evidently you can't adjust the output.

More common than I think you realize. If you've got a small softbox and place it 6 feet from your subject you've got a small light source, small catch lights, harder light with more contrast.

It's extremely common to work with modifiers that close to the subject, and it's not just for those with small studios. Many pros will work with a diffusion panel as close to the subject as possible without being in frame. Sometimes that's as close at 20- 24 inches.

I have to agree with Robert. I have 320's and 600's and the 320's I have a hard time getting down to 4 and 2.8 when I want to. I tend to keep my lights closer so I have a softer larger light source. Most of the time within 4 to 6 feet from the subject.

Hey Jeff,

If you want to get some idea of what kind of power will do what for you take a look at the specs of some strobes and you'll see that they typically will detail the output with an f stop, shutter speed, ISO and distance to subject. A little math will then give you other distances and values.


For example, take a look at this 1200ws strobe and click on the Specifications tab.

http://www.bhphotovide​o.com …Digital_Style_1​200RX.html

Ok, good.

Guide Number F-128.1 @ 3.3' @ISO 100, 1/250, with 48° Reflector

Let’s say then the strobe is mounted to a rail on the second floor on the side of the gym, several feet off the side of the floor, pointed at the ceiling. Assume there is ~15 feet to the ceiling and ~35 feet back to the floor where the subject is. So, 50 feet total distance, right? And for the sake of argument let's assume the ceiling is adequately reflective.

You're the engineer. You're gonna have to help me with the math here. I'm not sure where to start.

Phil Light wrote in post #6065422
I'm having a hard time getting my head around all I read regarding strobe power...

After seeing your avatar, I think I know what your problem is....

sfaust wrote in post #6067392
After seeing your avatar, I think I know what your problem is....

You'd think you would just pop that back plate off and cram it in there wouldn't you?

(Wise-a$$)