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How Much Power Do I Need? (low powered strobes)

Prince Cheap Here Again!

"I'm starting out and I don't know how much power I need…" someone recently said to me.

So, I just asked them a question right back. What type of images are you creating? The person said, "…Headshots, family portraits, actors, models, my teacher, mars and my mother…everything!" I responded, "Ooooooookaaaaay, you gotta figure out what you wanna photograph then set your power accordingly to the size of your subject. So get the most flash you can afford, then you'll be able to do power modifications to use that power monster in whatever your situation."

This article is designed to help you to start thinking about what you need and more importantly what you can do with what you have.

Rule number one for beginning photographers out there – get educated: Listen to the first LightSource podcast interview with Paul C. Buff of White Lightning & Alien Bees. There you'll learn about starting out with studio lighting and "power". Trust me… the last 20 minutes of this interview will absolutely make you think differently about what you "need".

School photography classes usually have the most powerful everything and it often handicaps photographers because they start out with the best equipment. The best things on earth have all come out of someone needing something and finding a way to do it! Photography is no different.

How can I possibly have any problems when I have a high power flash? A lot of photographers like the one I spoke with find themselves in this position after making their first strobe purchase because they purchased more light than they really needed. Think about this: you have a strobe that is 300 watt-seconds illuminating portraits of 1-2 people in your garage or home studio. You will find yourself turning its power all the way down and it still may be too bright for what you want. Then what do you do?

Option number one: You dial your cameras aperture down. Problem? The depth of field of your image drastically increases. You may not want that in every case.

Option number two: Back your light source up. This will reduce the amount of light that actually strikes your subject. However, this makes your light source smaller (not physically but visually – just think about the sun… its millions of times larger than the earth, but being so far away its only a tiny blip in the sky!). Smaller light sources create harsh light with very strong shadows. See this article about distance to subject and relative size.

Option number three: This option is my particular favorite. You could use some neutral density gel over your light source to reduce the light output. If you don't have access to gels, you can use black tulle fabric to do the same job. It is sometimes hard to work with but it gets the job done!

Here's the point: You CAN have too much light. When you do, you will have to spend some thought on how to reduce it (But the truth is better have and not need than need and not have!). This situation is when low power Britek PS-200H, Alien Bee AB160, Calumet Travelight 125 and other flashes below 200 watt-seconds come running to the rescue. These strobes, and many others, have very low maximum power output levels. This low power option can make running a home studio much easier!

Mr Fernandez 04 Take this home studio portrait for example – I used was a 125 watt El Cheapo Britek PS-200H flash bare bulb inside of a 60 inch Westcott Optical White Satin Shoot Thru Umbrella. The light was placed four feet away on the camera's left side (set to half power). The camera was set to F4.5, 1/125th, for ISO 100. There was a gold reflector duct taped to a light stand about 3 ft away on the camera's right side. Now I was photographing in the space of a tight living room filled with furniture.

If I had a light source of 300 watt-seconds which could not reduce its power down to about 1/8 power, 9 times out of 10 the image would not have the "pop" it does because I would not be able to use the F4.5 wide aperture! Now remember, there are many reasons to use high power strobes. But for most people portraits the truth is… you don't need much more than 100 watt-seconds of output.

You can do wonders with low power strobes. They are very powerful when you know how to use that power. As for our original question, 'how much power do you need', it still depends on the size of your subject and the quality of light you want. But for people portraiture, 100-160 watt-seconds can be effective. For more than five people I'd say you could get along with 300 watt-seconds effectively. In fact, a room full of people can be lit with a 125 watt-second light slamming into the ceiling. The light reflects off of it as nice as it would in a softbox or umbrella. Hint-Hint-Wink-Wink!

Take this food for thought and turn it into your attitude. You don't need one million watt-seconds to get the job done!



27 Responses to “How Much Power Do I Need? (low powered strobes)”

  1. Leroy Dickson Says:

    Very good article. It's often hard to get noobs to grasp the concept of too much when it comes to any equipment purchase.

  2. David Griffin Says:

    Thanks. After hearing that question so much I thought it would be a good idea to post about it.

  3. Scott Hampton Says:

    Hello.
    That was a great article. I wholly agree that lower powered strobes can do the job.

    I purchased a set of el-cheapo Impact strobes to play with and thought that I made a big mistake with such little power, seeing that the glorious Profotos were 600 watt-seconds strong. I NEVER go full power with these things. Maybe half power, shooting at f/8 and ISO 100. I also use them in a very small area; a home studio.

    One issue that I found though: If adjusting the power down doesn't keep consistent color you can run into warmer color shifts. I suffered that and had to "fix it in Photoshop" too many times. Quick solution: do a custom white balance before and then shoot away.

    Again, great article!

  4. David Griffin Says:

    That always works!

  5. sandra wilkes Says:

    I am turning a spare room into a "video studio". My one-person subject is standing in front of a white board speaking. There is a window behind the camera. I have been told that I need a 500Watt bulb right above the camera to film when there is no sun coming in. Do you think I need this much wattage? Would I be better with incandescent of flourescent? room is about 10X10. Thank you!

  6. David Griffin Says:

    Well Sandra, I dont have much experience with video lighting equivalents. But from info gathered from my video buddy. 500 watts in a 10×10 will be more than enough. He says you can get away with murder with 250, but he says 500watts with a dimmer is the way to go. I suggest you make a light panel and light your video the same way you would a still photograph. Of course you wont be able to keep a subject still.. but using broad sources should give you nice light.

    Just remember, 500 watts in a small 10×10 room… as long as you dont set anyone or anything on fire… it should work out great (especially if you can get that dimmer and have a test run)!

  7. sandra wilkes Says:

    Thanks!! I'm so new at this. I'll keep the fire extinguisher handy!

  8. tony Says:

    Hi,

    I completely agree with you that there's no need to go out and spend so much $$$ on powerful strobes. However, don't you agree that when you buy a strobe is not just for the power but also for the recycle time, light consistency and for the 5500K color temperature…not to mention accessories?

    Just wondering what your thoughts are on this. Great site and very informative…have you site as one of my homepage. Looking forward to more of your video tutorials.

    Thanks!

  9. David Griffin Says:

    Recycle time is important… but as long as were not talking about 3-4 seconds between each shot I dont think an amatuer will mind that much as long as he/she's getting pro images. Light color cosistency is not that important when you have things like photoshop elements (mostly free) and the pro version that will let you adjust color balance in seconds. (Provided that most people shoot or end up editing there images digitally.) As for accessories, hey thats what I'm beating up mostly. Accessories is the backbone of breaking your wallet after your strobe purchase. With a simple understanding of how light is modified you dont have to purchase every little thing a "company" says you "have to". Accessories simplyfy your life but they can also drain your wallet. Ask about the beloved Elinchrome Octalight… its a 7ft octagon shaped softbox that easily costs $1100 and is off limits for the average human! Do you really need it? No. I get similar softness from a 60" umbrella.

  10. kcinfocus Says:

    What gets me is even the cheap stuff is expensive. To a new-B like me it just looks like a light bulb on a pole with an umbrella in front of it. Please help me to understand why using "flash" lighting is different than if I go the the hardware store and get those big work lights and defuse the light. I do get the fact that it will be hotter than a son of a gun because they don't turn off.

    It sure looks attractive though when you can get two on a pole for less than $30 USD.

  11. David Griffin Says:

    Heres the skinny.
    A flash generates like 1,000 to 1,000,000 times the energy in one quick burst. Your lightbulb is measured in seconds. It takes your lightbulb (thats rated at say 100 watts) a whole second to produce 100 watts but your 100 watt strobe only about 500th a second! Thats why you can use many different apertures with flash versus… using slow (blur causing) shutters and apertures with hot lights. Its a speed thing. Go to the lightsource podcast and check out the very first podcast with paul buff of alienbees and whitelightning. He explains it totally for you in the last few minutes of the podcast.

  12. julia Says:

    hi,

    I am very happy to have come across your site, very useful tips on many different lighting issues, logical and easy to understand.

    I am actually writing from germany, and i am doing my university diploma on photography right now, maybe you can help me with a few questions.

    I am doing a "staged photography" projects, therefore i have built a little studio at home, like a "cube, with a 3m by 3m backwall and two sidewalls attached to it, all out of styrofoam. i have two subjects interacting on that stage, with props in the background. I have a large softbox, a second studio flashlight (150W) plus a strong video light (no flash) to use. a lot you d think for a relatively contained space. i have eliminated all ambient light. i am shooting on ISO 400, 1/60th of a second with f8, have my flashlights on full power and still hardly get enough light! how can that be? also, because I have only the FRONT to put my lights, since the stage is a cube with only the fron open, I cant light anything from the side. i have done a test shoot and the faces of the subjects dont really differentiate very much from the background (which has orange wallpaper on it), have you got any tips how I can light the background properly and still enhance the faces? maybe lighting from above might be an idea?

    sorry it is a long email, I d be very thankful for ANY help. sorry about the english.

    thanks

    julia

  13. david griffin Says:

    try this julia…
    set one light above the set aiming at the bg and the other light in the front aiming at the subjects (put it in an umbrella for a wider spread…
    set your aperture to f5.6 (f8 requires lots of light) this should do it if both your flashes are 150 watt seconds.
    this way each light should light 3 ft of space… the truth is if you had a 43" silver umbrella for the background just above and a 43" white umbrella for the front everything should be good as long as you're trying to use each light to cover 3 ft of space.
    the key will be you opening up your aperture. thats your issue. f8 requires lots of light.

  14. julia Says:

    thank you very much david. I will definately try your advice. i think it is fantastic that people like you give professional advice to people all over the world- just like that! it makes the internet a great thing!
    just one last question- will the f 5.6 not make parts of my image (e.g. the backdrop) go slightly soft? thats why I was using f8..?

    thanks again, take care, and all the best.

    julia

  15. david griffin Says:

    To: Julia,
    the shallow depth o field… nothing you can do about it. More light will fix this. You gotta have more light for a wider aperture.

  16. Brandon Says:

    I have a question that may be slightly off-topic, but I think it offers some pertinence: When looking for a strobe, should I be looking at the "true wattseconds" or "effective wattseconds" ? An Alien B400, for example, has 160 true and 400 effective; does this mean it's an over- or under-200 wattsecond performers?

  17. David Griffin Says:

    Everyone has mixxed feelings about this. Its a good question. Hard to answer but great question. Based on my (and a few other peoples tests) the B400 is a great flash regardless of true or effective watt seconds. I myself would purchase based on true watt seconds. My experience with a B400 however tells me that it outputs a bit better than I expected from a 160 watt strobe. With that being said… If you have a small space to photograph in… I'd go with the B400 kit if I could afford it. However with my el cheapo 125 watt Britek units I am able to do the same thing. The primary difference are build quality, reliability, features and customer service. I'd go with overall package and the AlienBee system is probably the hardest to beat on the planet.

    In all, would I take a 160 true watt B400 over another flash that is true rated at 300 watts output… No. Thats just my 2 cents.

  18. David Says:

    So good to see people like yourself hosting things like this, such a great thing for folks like me.

    Quick question: I've got my eye on the Interfit EX150a kit as it fits my budget (just came back to photography after 20 years, so I've shelled out a lot in a short time) and seems to have all I need for home use if I use my speedlite as a rim/background light, what are your thoughts ? For head and shoulders and some full length work ? Thanks !

  19. David Griffin Says:

    TO DAVID:
    First off… HAPPY NEW YEAR!!! GREAT NAME :)!
    Okay, sounds great selection on your kit. However I do suggest you eventually (Sooner than later) purchase a 5n1 40x60inch or a 42" (Disc) reflector from ebay. (You'll also need something to stand it on. Think lightstand, grip head and a reflector holder arm.) Why? You'll be able to use it as a fill (indoors or outdoors).

  20. Amy W Says:

    Mr. Griffin, I just wanted first to say thanks for answering people's questions on here ..not too many forums with such good tips.
    I also just had a quicky question- I'm trying to take pictures of still life (friuts, plates, etc) to oil paint, and I've never used flash…anything to recommend that's for up close & not too pricey? Thanks!
    (btw, will car reflectors work for basic photography needs?)

  21. David Griffin Says:

    TO AMY:
    Car reflectors are okay… but thats it. You'll need something that'll stay flat. That'll give a very even reflection of the light. I suggest the ebay 42inch 5n1 disc reflectors. Mines has 5 sides and only cost $42. As for macro suggestions… if your ur shooting digital with about 6 megapixels or more (DSLR camera that is), it should be good.

  22. Chris Stark Says:

    Mr Griffin – thanks for your informative and candid comments – very helpful for those of us trying to figure out the mono light market!

    I am a photographer who shoots a range of photos from portrait to group/event photography – including stage performances of Dance events. In most of these cases, I use available light. However, I am interested in expanding to more formal posing/lighting that will range from headshots to full length to groups of 10. At times, I may want to do dance studio shots of dancers in motion (i.e. leaps, etc)…

    Looking at Monolight combinations and willing to go up to 3 lights in a kit. Trying to get some tips on what I should consider for this range of photos. Have used alien b 800's for full lengths and like them, but am open to other manufs

    Thanks again for your efforts to help us Nu-Bs!

  23. David Griffin Says:

    TO CHRIS STARK:
    As I always tell people… If you can get the Bees… DO IT! If not… check out Britek/Linco Inc at http://www.lincoinc168.com, JTL lights are cool, Patterson Interfit work and there are a host of others. Heck I just ordered a new elcheapo flash from ebay seller studio4less http://stores.ebay.com/studio4less its 400 watts for $129! I'll mostly be using it A through a panel or B with the Ebay Octabox.

  24. John H Says:

    thanks for the info… i've been to so many shops that are trying to flog me 500w Elinchrom or Bowen kits… they are always saying that you never know when you will need it… i was quite happy with a 300w kit. the other thing is that is there difference between analogue power dial vs digital i.e. the bowens has a dial for power where as other brands has a button to dial up and down power and you have a visual to see what power you have set. .. thanks.

  25. FLOD40x Says:

    thanks a zillion for the info. I was gonna get me a 300w kits but wasn't sure if that was enough power. I hate to go wiv the crowd wanting mur without surety as to whether its the right amount of power or not. U jus saved me the stress of finding my way thru the crowd!!! Thanks man!!!

  26. Kirit Patel Says:

    I will be photographing Families at a church function to raise money. How many lights and what power will I need? I have a Nikon D2X and a Gossen meter. I also bought two 36×36 softboxes. I have a 10×20 Black muslin with the stand. I have a FlashWaves wireless transmitter/receiver. Thanks

  27. David Griffin Says:

    TO KIRIT PATEL:
    What flashes and how much output do they have?



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