# How do you calculate the maximum watts for the main studio flash strobe?

Some people say: maximum watts for the studio flash strobe depends on what one plans to shoot.

Other people say, it doesn'worth to have very powerful flash strobe if the studio is small.

What would you say? And why?

Studio about 60qm, main flash strobes could be maximum 400, 600, 750, 1000, 1200 and 1500w. Fashion and beauty shootings.

• A pedantic FYI: Watts are a measurement of Power which is Energy (Joules) divided by Time (seconds). Power is misleading in many cases as you can have high power with low energy over a short period of time. A million watt nanosecond laser pulse wouldn't light a match. WattSeconds WS is a measurement of energy (Joules), or total light on subject in this case. Total light can be reduced in two ways; less energy (brightness) and less time. Jan 31, 2021 at 17:44
• @user10216038, 100% agree. The thing is: different sources use different measurement units. I've seen w as watt, ws as watt/second and joule. In my experience w as watt is most usable by flash strobe manufacturers - but i can be wrong here too. Jan 31, 2021 at 17:54
• Yes, common usage is often different from technical definition and most people don't really care. Jan 31, 2021 at 17:59

The main issue most will face is not having the ability to turn the flash down far enough if you get a high powered strobe.

But having more power allows you to use larger modifiers, and it allows you to use lower power settings for faster flash durations (freezing motion w/ IGBT strobes) and quicker recycle times.

For most typical type fashion/beauty work I would say 600WS is completely adequate as long as it has enough adjustability (and consistency). It might be actually more than you generally need; but unlikely to be less than you will ever require.

• Turn flash down far enough - if the flash is dimmable, it should be no problem, correct? Jan 31, 2021 at 15:26
• Easy way to fix that misconception… put a regular strobe an inch from an object. Try to get the flash short enough that it won't white-out the centre of the object. Jan 31, 2021 at 15:39
• @Evgeniy, say you have two strobes that have 4 stops adjustment range; one is 1200ws and the other is 200ws. When both are set to minimum (1/16) the 1200 will still be at 75ws and the 200 will be at 12.5ws. And it is highly unlikely that you will find a higher powered strobe that can be turned down as far as a lower powered one; the bulbs are not designed for that (and it causes color shift issues). Jan 31, 2021 at 17:17

I would first choose the aperture based on the span of depth of field desired. Let’s assume you want this to be shallow. Start with f/5.6. You can adjust as we proceed. Let’s do with a two light set-up. This will be a main placed high and off to one side. Next place a fill at about lens height, placed somewhat near the camera.

With the only the fill operational, shoot a series of test shots using the watt-seconds adjustments. Let’s pretend the 750 setting produced a reasonable exposure.

We want the fill to be subordinate to the main. Try a series setting the main a 1000 then 1200, then 1500. Examine this series. Use the ISO setting to tune the exposure.

Your series will display a contrast change. Choose the contrast result that suites your needs.

Found this from google, thought I'd add my 2cents as this seems to be an opinion based question. Size of studio doesn't make a huge difference unless you bounce light off the walls. Power depends on what you want to shoot and how you shoot it.

I have 3 studio strobes, 500w/s each. I shoot large products where the front is generally is about 2m squared in size and I generally only need to shoot on about 1/2 or 2/3 of maximum power on average. Main light at just below full power, fill light at just above minimum power. For portraiture, my strobes are perfect, maybe overkill in some situations.