What the hell is watt second and how many do you need?
In today’s video I explore how many watt seconds you may need in each situation so that you can make the right choice when you’re purchasing lights for your studio and on location.
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Music: Evolution by Bensound
Comments
38 responses to “How many watt-seconds do you need for portrait photography?”
I need 2 600ws for a single person full body shoot when sun is out there. Later in the evenings 1 600ws is enough. Waiting for global shutters to get cheaper.
Thanks for the video, John! I saw the photo at 0:29 and thought it might be cool if you could make a video about lighting (or even posing) groups. This has always been a challenge for me and perhaps for most studio photographers as well. Cheers and keep rocking mate!
My Nikon d800 I need to take full focus of object
Is 600w enough for shooting portraits outside in a sunny day and for an out door weddings?
How many watts of continueous light does one need to capture fast movement like shutter 125 or 250?
Your numbers are spot on, great information! I use a 1200 pack & head system at the lowest settings. That is 225 ws through a hazylite box and 75 ws through a 3×4 soft box with a model 3' from the lights. I meter f/10 – f/11 at ISO 50. Really, the best advice is power that can be adjusted lower. My 90's gear just cannot be set lower and that isn't ideal for a small studio. ND gels could help, but honestly, I like a lot of DOF in studio shots.
Hey John, you have recently made test for Elinchrom ONE flashes. From your experience, what will be the largest possible softboxes (octa) to use in general situations with those flashes? (for example Rotalux Octa 100cm Deep or Rotalux 135cm) Do you have any more comments to give? I consider to buy El. ONE flashes as my main lights for occasional portrait projects. Thank you for the answer and your great content!
Just thank you. Those very accurate little subject are so important to explain !
That was fantastic. I have 2 godox AD 200s and 1 godox ad600 and they are perfect for most indoor and outdoor shooting situations! But now understanding watt seconds has brought more understanding to what I do! So I just learned that my speed lights are 76 Watts which are good for certain things!
Thanks for a very helpful video John. What are you go to 500W lights that you talk about? I recently got a set of BRX-500 lights and while it's nice to have that power, I can only go down to 31W, which is quite limiting if I want to use small modifiers up close. So it's good to have both options.
Well explained. Thanks for the video. I also like your calm style.
Just found your channel sir.
Thank you very much John for yet another wonderful and informative video.
I have a question to ask about the way you have your Beauty Dish mounted (timestamp: 3:21). I always have problems with my Beauty Dish mounted horizontally on a C-stand grip arm. Gravity pulls the Dish down no matter how much I tighten the arm or the flash's holder. Your solution looks perfect, and I wanted to know what type of attachment (arm) is that?
Thank you in advance for your reply.
John, I absolutely love all of your videos. I taught myself photography during the pandemic and your videos have taught me A LOT. Do you find that for a beginner, someone who may not want to use a 7' umbrella or 5' softbox yet, that speedlights put out enough light?
Hello John, thank you for the overview of the watt second topic. It is of great value to highlight the technical side of photography, such that new and seasoned photographers understand how to best utilize their equipment. With your permission, I would like to provide some clarification on the term, watt second. Watt-Second is a statement of energy as work, Watts vs. Time. Just as our electric bill is stated as KiloWatts per hour, KW/h. In the case of electronic flash, Watt-sec is the statement of the stored energy in the flash capacitor. Ex: filling a glass of water and pouring it out over a toy paddle wheel is stored energy converted to work, if the paddle wheel is connected to a generator. So, Watt-seconds of stored energy is translated into light as the energy flows through the flash tube. The higher the value of Watt-Sec's the more light emitted from the flash tube. Of greater importance, however, is the flash guide number, GN. A flash guide number is the product of flash distance to the subject (times) the f-stop. This takes into account the amount of stored energy, the reflector efficiency and the inverse square law of light fall off with distance. For a complete technical and pictorial explanation of High Speed Sync vs. shutter based flash synchronization, please view my blog article https://www.davidlloydphoto.com/blog/2017/5/5/cl-200x-hss-measurements. I sincerely hope this will provide greater insights into the technical and practical side of flash photography. Best regards, David Lloyd CPP (former flash engineer for Vivitar Corp.)
2400 watt/seconds…. per light source.
And you must shoot every image at an aperture of f/22 or smaller.
No mention of increasing ISO with lower power strobes?
Great video. Ty.
y are in my top 5 photographers
Thank you, this was so informative. And incredibly well-made.
Heck looking sharp John.
At last, clarity.
One size doesn't fit all! Depends on what kind you're doing, where you're doing it, whats the look your going for, You want shallow DOF, you want HSS, You want f/8-f/11, you doing portraits or fashion … Sometime 50ws all you need, sometimes multiple units of 2400 ws or more is needed. Sometimes you don't even need WS. Go study the greats… Penn, Avedon, Stern, S.Meisel, Ritts, Moon, Hiro, Karsh, Newman, etc…
I've never even heard of this! Gonna take this into my photography.. Great video 🔥
How many of ANYTHING do I need? MORE!
N’SYNC Speed hahaha
Everything you say is correct, but a couple of important points . . . Firstly, distance is key, and far more power is needed when the distance from light source to subject is greater than it should be (inverse square law). And secondly, when shooting indoors in a controlled environment with a minimum of unwanted ambient light, low power can be largely compensated simply by increasing the camera ISO setting without noticeable loss of image quality.
What is also important is how low you can go with power. Elinchrom has the lowest power 7Ws. This is sometimes too much if you want to use aputure f1.8 or so,even with big deep umbrella for instance. No everybody using f10 in studio.
🔥🔥🔥
Thanks John for the tips. Please in an outdoor portrait photoshoot, what size of modifier & watt/sec is Ideal using speedlight flash?
Hi John,
I think it can depend on what and how you shoot also. Along with watt seconds always want to know the T0.1 flash duration of a light as well.
A lot are measure in the marketing value T0.5 which for stopping action is useless.
The studio lights I use a Godox based (Pixapro in the UK) The Storm II 400 and 600 heads. They work light speedlites and the battery powered units in that they give a shorter flash duration on lower power settings. With the 600ws heads I can get around 1/1400th sec T0.1 at around 1/4 power which affords me stopping power and output.
Generally I will always go for a higher powered light over a lower one even for the studio because I will gain ( with the right light) a shorter flash duration at an equivalent power to a lower powered light.
Not enough people consider flash duration during the purchase of a flash.
Great video, thanks!
Really enjoy your calm and thorough presentation. This is a great explanation of a confusing subject. Strobes, incandescent light bulbs, and audio amplifiers are marked by the power they consume, not the volume they put out. Not at all saying you are wrong here… the products are both rated and sold with a (sort of) industry standard marketing term.
This is video is a great synopsis of what is needed to photograph in different settings. 👍
I recall you using an optical snoot for accenting in some photos. I've been meaning to ask if you are using it with flash and what power does it need to not be washed out. I acknowledge the other variables involved; distance, lense, gobo, backdrop, main lights etc… this is just a general question. BTW, thanks you for the effort you put into these tutorials.
Never clicked on a video so fast. Been talking about tis topic to a few photographers recently.
Oh wow, you explained it perfectly John Gress thank you! Love the sample image of a group outdoors and yes its better to dial down the power of the source than running out of it. All the best for you and your Team as the world opens up again.
Cool Video again John. very practical and also strategical. In My beginning i startet with way to powerful Elinchrom Flash Units. What was the problem with that, you might wonder: The Flashes of this days where not able to deliver very, very low power and for certain pictures it is important to have a wide range. As you use Elinchrom you certainly know their number system. Today in need power vom. 0.1 = 7WS up to 6.3=500WS (Elinchrom ELC500 / ELB500) per unit. Maybe the question could be extended to: "how much range in power do one needs" ..another question/aspect is the refreshing/charging times. Working with moving Athletes, Musicians, Children fast refreshing is a real issue.
The Elinchrom number/Ws system
Setting Ws
0.1 7
1.3 15
2 25
2.3 31
3.3 62.5
4.3 125
131
5.3 250
300
6 400
6.3 500
522
600
7.3 1200
8.3 2400
Use guide no. – Watt sec. does not say anything about how powerful the flash are….
watt-seconds is a measure of the energy available in the capacitor.
A GN it telling you the effective power output taking in the reflector etc given in the GN specs. a WS rating is only telling you how much power the capacitors will hold. It's like comparing Horse power to 1/4 mile race times, a higher horse power should run faster, but if one is a little import and one is a pick up truck which one will get there faster with the same horse power.