How much strobe power do I need?

[Phil Light]

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.

[jr_senator]

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.

[Kittygraphix]

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 :D Great for studio lighting and outdoor use :D

[airfrogusmc]

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.

[pcunite]

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! :)

[Phil Light]

...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.

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

Just a simple reflector. No reason for modifiers for this

....3. Will you be shooting outside?...

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. :D

[TMR Design]

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.

[jr_senator]

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.

[Wilt]

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!

[TMR Design]

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.

[ueb0258]

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.

[TMR Design]

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.bhphotovideo.com/c/product/283824-REG/Elinchrom_EL_20727_Digital_Style_1200RX.html

[Phil Light]

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. :o

[sfaust]

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....


:lol::lol:

[Phil Light]

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


:lol::lol:

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

(Wise-a$$) :p

[Phil Light]

(I think I finally stumped Robert) :D

[TMR Design]

(I think I finally stumped Robert) :D

No Jeff,

Just doing a million things.

If I'm doing the math correctly we can take the numbers given and elaborate a bit. Doubling the distance increases aperture by 2 stops.

f/128 @ 3.3'
f/64 @ 6.6'
f/32 @ 13.2'
f/16 @ 26.4'
f/8 @ 52.8'

[Phil Light]

I think that's finally what I needed to know. That tells me that 1200ws would give me more than what I need. Assuming I would probably use something probably between f/2.8 - f/5.6, and I would not be opposed to shooting as high as 400 ISO. Then I could dial the power down and get a faster recycle time too.

Thanks Robert.

[TMR Design]

Correct-a-mundo Jeff.

My pleasure.

[airfrogusmc]

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.

Almost every single subject portrait that light is no farther than 3 ft away from subject. Quality of light is very important to me and usually with one person my softbox is just outta the view of the lens a B/G light and reflector for fill. But the quality is what I get first then dial in desired f/stop.

Also if you back the light up from 2 to 2.8 ft thats a one stop loss. From 2.8 to 4 ft thats another stop. 4 to 5.6 thats another. 5.6to 8 well you see the trend. And the light increases 1 stop if you do the reverse.

[sfaust]

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

(Wise-a$$) :p

You're right. I forgot about the backplate and the 128 pin computer link connector hidden behind it. I would image you can download every piece of photographic knowledge in about 32 seconds.

But the first accident, well, its all wiped out ;)

[Phil Light]

You're right. I forgot about the backplate and the 128 pin computer link connector hidden behind it. I would image you can download every piece of photographic knowledge in about 32 seconds.

But the first accident, well, its all wiped out ;)

I'm sorry, what were we talking about? (I have a headache)

[AB8ND]

Where is link to anAlien Bee article titled How Much Power
http://www.paulcbuff.com/forums/viewtopic.php?t=52
One quote that is interesting is

"Our experience is that far more users end up wishing they had bought lower power lights (i.e. the AlienBees B400) rather than higher power."

For basketball you can, and this is done, mount 2 580EX's or Nikon SB800 high in the bleachers aiming them to cross at the key , at 1/2 power these should give plenty of light to balance with the ambient of the gym (normal gyms anyway). Now if you have endless dollars (read that a Sports Illustrated assignment) you can mount strobes to the rafters and light the whole gym. I remember reading that some pro arenas have strobes permanently mounted and photographers (from recognized media)are issued PW's. I sure these are all strobes with the most power available.

Jack

[Phil Light]

... I remember reading that some pro arenas have strobes permanently mounted and photographers (from recognized media)are issued PW's. I sure these are all strobes with the most power available.

Jack

I was told there is a pro here in town who has his own lights permanently mounted in several different sporting arenas in this city. It was estimated that he has about $40,000 invested just in lights.

The day I can afford to buy $40,000 worth of lights to permanently mount in someone else's facility, that's when I'll know I'm successful.

[Wilt]

Where is link to anAlien Bee article titled How Much Power
http://www.paulcbuff.com/forums/viewtopic.php?t=52
One quote that is interesting is

"Our experience is that far more users end up wishing they had bought lower power lights (i.e. the AlienBees B400) rather than higher power."


Precisely what I have been trying to tell people for a long, long time (and I never read that advice on PCB web site)

[Phil Light]

..."Our experience is that far more users end up wishing they had bought lower power lights (i.e. the AlienBees B400) rather than higher power."...

Precisely what I have been trying to tell people for a long, long time (and I never read that advice on PCB web site)

This makes perfect sense. No argument from me. I assume though that most studio lighting newbs like me assume that the power can always be dialed down. We just want to make sure we have the most power and versatility when it might be needed. But it sounds like there is no "one light fits all" answer.

[TMR Design]

Precisely what I have been trying to tell people for a long, long time (and I never read that advice on PCB web site)

Indubitably :D

[Hermes]

Precisely what I have been trying to tell people for a long, long time (and I never read that advice on PCB web site)

I've tried to do the same and it really is futile. New photographers seem to be stuck in the 'more is better' mindset and completely unwilling to accept that buying higher-powered lights will often rob you of useful, lower power settings and gain you only impractical, higher ones.

[TMR Design]

I've tried to do the same and it really is futile. New photographers seem to be stuck in the 'more is better' mindset and completely unwilling to accept that buying higher-powered lights will often rob you of useful, lower power settings and gain you only impractical, higher ones.

I agree. It's a fight but I think we (you, me, Wilt) have made some progress in that department and seen many switch to lower power strobes. If it's explained in a real world practical way instead of just throwing numbers around then I think it makes more sense and potential buyers come to understand the concept of too much power being a bad or impractical thing, not to mention more costly.

[RichNY]

The amount of power you will need for strobing a gym is going to be greatly dependent on how far away you mount the strobes.

One big thing to consider is the flash duration when shooting sports. This is probably the most commonly used setup for shooting sports photography in gyms: http://www.dynalite.com/sportspkg.shtml

[Phil Light]

The amount of power you will need for strobing a gym is going to be greatly dependent on how far away you mount the strobes.

Right, what I had in mind was something temporary/portable/flexible (enough power) so I could travel to different gyms. I rarely shoot at the same place more than once or twice a year.

One big thing to consider is the flash duration when shooting sports. This is probably the most commonly used setup for shooting sports photography in gyms: http://www.dynalite.com/sportspkg.shtml

I began to realize this as I read the specs on many of the lights. With many of them, the duration is so long that it would virtually defeat the purpose of using strobes. It's not going to do anyone any good if the subject is well lit, but motion blurred. I wouldn't even consider anything with a longer duration than 1/1000 at whatever power level I need.

I'm also beginning to realize that to get what I would really like to have I may have to save pennies for a little while longer. :cry:

Thank you for the link!

[TMR Design]

Hey Jeff,

Unfortunately that is the conclusion that many come to, and it's worth making the right choice rather than getting something that won't do the job. Your requirements made it difficult to get away with a low power inexpensive solution.

[Phil Light]

Hey Jeff,

Unfortunately that is the conclusion that many come to, and it's worth making the right choice rather than getting something that won't do the job. Your requirements made it difficult to get away with a low power inexpensive solution.

I'm not surprised. If I can get to a point where I'm making decent money doing this, I'll consider buying whatever it takes. Right now I'm not very close to that. Ironically, if I just owned them and had the capability to strobe games I would be able to get more work. But I am not in a position to invest thousands so that I might be able to make it back.

For something like this I would only buy it if I can justify it by making money with it. With cameras and lenses though, I'm not so picky. I'll buy those just because I want them.

[Jim M]

I wish I was better at estimating distance. I might have some useful information.

I shoot drag racing pictures and a lot of the action is after dark. A couple of years ago, I started using Novatrons without modifiers to light things up. My current setup is two heads with a 1600 WS power pack. I split the power evenly so there is 800 WS going to each head. Depending on which side of the track they are on and the color of the car (yes, it does matter) I've been shooting at between f/7.1 and f/10 at ISO 500 with a base exposure of f/8 if the pack is set to full power. I like the depth of field since the place isn't too well lit and I've been known to get a little imprecise focusing from time to time. I actually started doing this with a 600 WS pack and I moved up. You'll be surprised at how quickly you will learn what the light intensity is in various places and with various tones. I don't know if this relates well to an enclosed gym, where the stray light will be bounced rather than shot off into space, but it is some real world experience that may give you a starting point.

I should also add that the reason I use Novatron pack and head units is because that is what I had. It works well enough for me, but other than that, I have no particular endorsement for brand.

[Wilt]

I wish I was better at estimating distance. I might have some useful information.
.

If you have a shot where the EXIF information is available, we can estimate the shooting distance simply if there is someone of known (approx) size in the photo to scale the overall photo, because then the FL of the lens can be used to determine the shooting distance!

[susymike]

I shoot in small town gyms with 2 Novatron 400ws heads pointed at the ceiling using either a 20D or 5D @ 800-1250 ISO. Typical settings are 200th@f6.3, camera set to Manual. Lens is usually Canon 28-70 2.8, Sigma 15-30 2.8, sometimes Canon 70-200 2.8 IS. Usually wider angle for boys than girls.
The two examples are w/ the 5D @1250 ISO, 200th@7.1 with the 28-70
They have been cropped quite a bit but are crisp

[TopGear1Ds]

I shoot in small town gyms with 2 Novatron 400ws heads pointed at the ceiling using either a 20D or 5D @ 800-1250 ISO. Typical settings are 200th@f6.3, camera set to Manual.

Why the restrictive aperture setting? Couldn't you be iso 200ish at the same lighting using f/2.8 instead?

[bobbyz]

You can use soemthing like 285HV to light basketball game. Look here at what Dave does.

http://www.davehoffmannphoto.com/imageEngineer/2007/12/follow-the-bouncing-ball/

[Tomi Hawk]

Sigma 15-30 2.8
Sigma makes a 15-30mm 2.8 version? ???
I have the same lens .. but it's a 3.5/4.5 .. :confused:

[transcend]

I've tried to do the same and it really is futile. New photographers seem to be stuck in the 'more is better' mindset and completely unwilling to accept that buying higher-powered lights will often rob you of useful, lower power settings and gain you only impractical, higher ones.

ND gels can solve that pretty quickly...

[Hermes]

ND gels can solve that pretty quickly...

ND gels will also cut your modelling light down to near-useless levels, not to mention enclosing the bulb thereby absorbing light and generating huge amounts of heat which can and will cause the head to overheat.

Then there's the issue of trying to evenly gel octabanks, umbrellas, beauty dishes, strip-boxes and all the other modifiers that are the staple of portrait & fashion photographers. Neither Rosco or Lee make gel-rolls big enough to cover the majority of my large modifiers even if I did want to spend huge amounts of time (not to mention money) constantly fitting and swapping gels to lower their output - if you have an easy solution then I and studio photographers everywhere would be glad to hear it.

[transcend]

You don't gel the modifier, you gel the head.

Ps: I shoot in studio all the time.

[Hermes]

You don't gel the modifier, you gel the head.

Ps: I shoot in studio all the time.

care to elaborate? how, for example, would I gel an Elinchrom octa or a beauty dish with out totally screwing up the light distribution?

[sfaust]

care to elaborate? how, for example, ...

Ditto. I shoot products in the studio all the time, and I've never found a good easy solution to use gels on strobes while also using modifiers.

[transcend]

Use a clip on/clide on etc diffuser holder. There are some 7" Speedo models that work with the 7" elinchrom reflector quite well. (They make various sizes for different reflectors.) This works quite well with an umbrella or any other modifier where you will be using a reflector.

Here is a good example.
http://www.vistek.ca/store/ProPhotoLightShaping/161815/speedotron-7-gel-holder.aspx

For softboxes, I have used and seen others use multiple internal baffles in the box to reduce light output in certain situations. Profoto and many others make fullsized, specialty diffusers to add to their own softboxes. Profoto even makes a 7' (yes foot) diffuser to add to their large boxes. For a beatydish etc, there would definitely be a problem. I have to use mine at close to minimum output most of the time (Rangers).

Although I agree that clearly, if you have a 2400w light in a 8'x10' room, you are going to have a problem almost every time. Most companies DO offers options however.

[Jim M]

If you have a shot where the EXIF information is available, we can estimate the shooting distance simply if there is someone of known (approx) size in the photo to scale the overall photo, because then the FL of the lens can be used to determine the shooting distance!
Sorry, I lost track of this thread when I got quite busy.

That would be fine if the lights were where I was, but the lights are upstream and off to the side. I'll dig around for a picture.

[Jim M]

If you have a shot where the EXIF information is available, we can estimate the shooting distance simply if there is someone of known (approx) size in the photo to scale the overall photo, because then the FL of the lens can be used to determine the shooting distance!
Well Wilt, I hope you can make something out of this. It is one I haven't cropped. It is quite low res since I took it from the track web site and I compressed it once and the track webmaster compressed it again. The pertinent EXIF data is 80mm at f/8, ISO 500. I thought this was two heads, but this may have been from the night that I inadvertently shut off one of the heads and hadn't noticed it. (Closer examination of a bunch of images tells me that it was both lights. The one farthest back isn't casting much of a shadow, but it's there.) Like I say, I don't know if you can figure anything out from this since the lights aren't at the camera position.

[Hermes]

Use a clip on/clide on etc diffuser holder. There are some 7" Speedo models that work with the 7" elinchrom reflector quite well. (They make various sizes for different reflectors.) This works quite well with an umbrella or any other modifier where you will be using a reflector.

Here is a good example.
http://www.vistek.ca/store/ProPhotoLightShaping/161815/speedotron-7-gel-holder.aspx

For softboxes, I have used and seen others use multiple internal baffles in the box to reduce light output in certain situations. Profoto and many others make fullsized, specialty diffusers to add to their own softboxes. Profoto even makes a 7' (yes foot) diffuser to add to their large boxes. For a beatydish etc, there would definitely be a problem. I have to use mine at close to minimum output most of the time (Rangers).

Although I agree that clearly, if you have a 2400w light in a 8'x10' room, you are going to have a problem almost every time. Most companies DO offers options however.

Using a diffuser involves changing the fundamental light characteristics of a modifier and is not the same as turning down the output at the source. On top of that, very few manufacturers make baffles that span the entire softbox interior so adding more density to them will just reduce the light in the centre while the edges get comparatively brighter. I hand-make my own baffles and deflectors which do actually go corner-to-corner and in most cases the narrowest point that I can fit them across the flash tube is still wider than the widest gels you can buy. You'd need to gel a softbox evenly corner to corner in order to reduce the output without changing anything else and that simply isn't possible in most cases. Same thing with beauty dishes and indirect banks. Once you've got rid of all that you're left shooting with bare reflectors and umbrellas (assuming that you don't want to use a central umbrella fitting in which case you're left with just reflectors).

[Wilt]

Well Wilt, I hope you can make something out of this. It is one I haven't cropped. It is quite low res since I took it from the track web site and I compressed it once and the track webmaster compressed it again. The pertinent EXIF data is 80mm at f/8, ISO 500. I thought this was two heads, but this may have been from the night that I inadvertently shut off one of the heads and hadn't noticed it. (Closer examination of a bunch of images tells me that it was both lights. The one farthest back isn't casting much of a shadow, but it's there.) Like I say, I don't know if you can figure anything out from this since the lights aren't at the camera position.

Lights not at camera position makes this more guesswork. I was assuming lights at camera position when you referred to your bad estimation of distance, and being able to use AOV of the lens vs. what fractional part of that field was an object of known size.
Measuring pixel intensity across the upper front edge of the car makes it appear to fall off -1EV across the car's width; assuming 6' wide car front that would put the light about 16' away from the car. How's that for a guess?!

[sfaust]

Using a diffuser involves changing the fundamental light characteristics of a modifier and is not the same as turning down the output at the source. On top of that, very few manufacturers make baffles that span the entire softbox interior .....


I've basically found the same thing. There is no good way to use ND gels on modifiers without changing the light generated, with the exception of standard reflectors, barn doors, and snoots. Nobody makes anything that works well for softboxes, beauty dishes, etc, and I've had to resort to extra diffusion with mixed results (color balance changes, light quality changes, etc.)

[Jim M]

Lights not at camera position makes this more guesswork. I was assuming lights at camera position when you referred to your bad estimation of distance, and being able to use AOV of the lens vs. what fractional part of that field was an object of known size.
Measuring pixel intensity across the upper front edge of the car makes it appear to fall off -1EV across the car's width; assuming 6' wide car front that would put the light about 16' away from the car. How's that for a guess?!
I'm thinking light falloff is more a function of curvature. The front, hood, and top of the car are all curved surfaces and since the light is pretty far to the side, would have light fall off regardless of the distance from the vehicle. The light falloff from the near lane on one side of the track to the far lane on the other side is less than a whole stop. Since the distance down the track varies some from image to image, I have the lights as far off to the side as I can get them and no farther down track than necessary to ensure light on the front of the car. The inverse square law definitely applies. I'll try to get an actual measurement, but it will probably take a while.

[Phil Light]

With regard to the "volume" of light, would it be correct to assume that a 400ws strobe (at full power) would put out approximately the same amount of light as a standard 400 watt bulb?