# Studio Light Power Question?



## keithfullermusic (Nov 21, 2014)

So, I have have two Bowens 500R studio lights. They are rated at 15Ws-500Ws over 5 stops. But what exactly does that mean?

To me I'm guessing that every time a turn it up a stop, it doubles the Ws - but I might be wrong. I would think that it actually has 6 stops which go as follows:

1 - 15Ws
2 - 30Ws
3 - 60Ws
4 - 120Ws (roughly 125)
5 - 240Ws (roughly 250)
6 - 480Ws (roughly 500)

I should also note that I have two dials:

The first is for complete stops (1-5)
The second is for 1/10th stops (0-1)

It actually goes up to 6 (the full stop dial turned to 5, and the 1/10 dial turned up to +1.0), so did Bowens list that incorrectly?


THEN, that leads to my next question - how much dimmer are the 400W and 250W lights? Is the 400W less that 1 stop at full power compared to the 500W, and is the 250W exactly one stop less than the 500W at full power?

I only ask because I'm looking to get a two more lights, and I want to keep my options open. Thanks.


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## AcutancePhotography (Nov 21, 2014)

I have this site bookmarked as it has a lot of good information. I hope it helps you too. 

http://www.scantips.com/lights/flashbasics2.html

In your example (1-6) that does represent 5 stops as there are five increments between 1 and 6.


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## privatebydesign (Nov 21, 2014)

You have 5 stops of adjustment over a six stop range. For example if you are at full power, 500Ws, you can come down five stops to 15Ws. The settings on the flash would be :Stops dial 1, Tenths dial 0.0, for 15Ws, now go up to 5 on the Stops dial and you have gone up four stops, then go to the Tenths dial and go up 0.9 stops for a 4.9 stop adjustment range across a 5.9 stop output range.

If they had a zero on the Stops dial and you could input just 0.1 on the Tenths dial you would have full adjustment range of your actual output range.

You are right, the numbers are straightforward, 400Ws is close to 1/3 stop less than 500Ws and 250Ws is one stop less than 500Ws.


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## keithfullermusic (Nov 21, 2014)

AcutancePhotography said:


> I have this site bookmarked as it has a lot of good information. I hope it helps you too.
> 
> http://www.scantips.com/lights/flashbasics2.html
> 
> In your example (1-6) that does represent 5 stops as there are five increments between 1 and 6.



thanks for the link. it was very informative.


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## keithfullermusic (Nov 21, 2014)

privatebydesign said:


> You have 5 stops of adjustment over a six stop range. For example if you are at full power, 500Ws, you can come down five stops to 15Ws. The settings on the flash would be :Stops dial 1, Tenths dial 0.0, for 15Ws, now go up to 5 on the Stops dial and you have gone up four stops, then go to the Tenths dial and go up 0.9 stops for a 4.9 stop adjustment range across a 5.9 stop output range.
> 
> If they had a zero on the Stops dial and you could input just 0.1 on the Tenths dial you would have full adjustment range of your actual output range.
> 
> You are right, the numbers are straightforward, 400Ws is close to 1/3 stop less than 500Ws and 250Ws is one stop less than 500Ws.



great - thanks for the clarification. i was debating getting a 250W light for the background. I often find that even with my main lights turned up all the way, and the background light turned down all the way - the BG is still too bright. this is because i often have large modifiers on my main lights (which eats up the light), and just a standard reflector on the BG.

a 250W light should essentially be 1/2 the brightness at its lowest stop compared to the 500W at its lowest stop, which would be great. I would also assume that the 250W at full power would be the same thing as my 500W at one stop below full power. clearly, the recycle time on the 250W is going to be slower, but I think it will be ideal.


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## IMG_0001 (Nov 21, 2014)

I am not very experienced with studio lights but I've researched them a bit in the last few months and I would like to add a couple comments.

First is that from my understanding, the Ws rating is not really a normalised and directly comparable measure. It should be comparable within a given brand, but might not be between brands. For example, the light output from similarly rated lights might differ because of the tube and electrics\electronics efficiency, reflector geometry and reflector efficiency.

Second, because your actual flash has 5 stops does not mean that a lower powered flash will also have five stops. You might pretty well have a 4 stops 250Ws light that has the same minimum output as your larger strobe. Apparently, the actual precision and range of adjustment appears to be one of the most evident compromise of cheaper strobes.


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## keithfullermusic (Nov 22, 2014)

IMG_0001 said:


> I am not very experienced with studio lights but I've researched them a bit in the last few months and I would like to add a couple comments.
> 
> First is that from my understanding, the Ws rating is not really a normalised and directly comparable measure. It should be comparable within a given brand, but might not be between brands. For example, the light output from similarly rated lights might differ because of the tube and electrics\electronics efficiency, reflector geometry and reflector efficiency.
> 
> Second, because your actual flash has 5 stops does not mean that a lower powered flash will also have five stops. You might pretty well have a 4 stops 250Ws light that has the same minimum output as your larger strobe. Apparently, the actual precision and range of adjustment appears to be one of the most evident compromise of cheaper strobes.



I didn't really think about that - different brands having different ratings, but it makes sense. Fortunately, I have two Bowens 500R's and I'm thinking about getting the 250R's to go along with them. I would imagine that they would have similar performance, only the 250's would be a stop dimmer at both ends compared to the 500's - the 500s are 15-500, and the 250s are 7-250.


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## IMG_0001 (Nov 22, 2014)

keithfullermusic said:


> IMG_0001 said:
> 
> 
> > I am not very experienced with studio lights but I've researched them a bit in the last few months and I would like to add a couple comments.
> ...



If you are tout stay within the same brand and series, the outputs should be consistent with the rating.,


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## Koemans (Nov 22, 2014)

keithfullermusic said:


> So, I have have two Bowens 500R studio lights. They are rated at 15Ws-500Ws over 5 stops. But what exactly does that mean?
> 
> To me I'm guessing that every time a turn it up a stop, it doubles the Ws - but I might be wrong. I would think that it actually has 6 stops which go as follows:
> 
> ...



I have a bowens 250watt with a large travelpack kit. 

You have 5 stops of power control since it starts at 1.0
Altho the 500watts kits are cheaper, it will give you far less control in areas with not much room available, especially on location.
It is a fools mistake to think more watts are better. Unless you want to Fry insects from 20 meters or you want to make classroom photos, go for a 250watt kit. 250watt also Works longer on location with the travelpack


And btw, it Works a bit different with strobes thanf-stops on a camera. It is just 500 watt split over 5 stops. What i am trying to say is : use a lightmeter to save time

Your calculations appear to be correct, the official specs say the range is 15-500ws


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