How much lighting power do you need?

Garry Edwards

Garry Edwards

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Garry Edwards
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A simple question, not such a simple answer:)

But this free download may help. It's a (very) brief extract from my tutorial on Studio Lighting & Equipment. If you want to read the other 67 pages and look at the pretty pictures you'll have to pay:crying:

The question of how much power is subjective, different people have different needs and so have different views. You may or may not find it helpful - please feel free to comment.
 
Not a lot of interest in this one then...:crying:
 
Well I found it interesting Garry! :D

A very nice valuable contribution. (y)
 
The silence on this one is quite loud Garry.
I bought your lighting guide a few years back and in the end decided on 2 Bowens Gemmini 500 units and 2 octoboxes 1 @95cm 1 @120cm and a couple large reflectors . I mostly shoot portraits and small group shots and find these lights great to work with and more than enough power for this type of photography . Strangely I find myself mostly using only one light and a reflector for portraits.
I use a Bronica ETRSI 6x4.5

Guid Health:beer:
 
Bronikon,
You made a good choice, Bowens is one of the leading brands. 500J can be a bit on the generous side for people using cropped sensor DSLR's (but still perfectly usable) but is ideal for your ETRSI, where you can get away with shooting at f/22 if you have too much power.

There's nothing strange about using only 1 light and a reflector for most portraits, it makes sense because studio photography is about emulating 'natural' lighting conditions and there's only 1 sun in nature. Some of the top portrait photographers only use one light, with people like William Coupon it's become a trademark.

I wrote this guide basically because 'How much power do I need' is one of the never-ending questions on forums.
 
I guess the problem with deciding how much power you need is that many of the light modifiers don't specify how many stops you loose, and it is only in using them that you find out.

For example if you want to find out what is the effect on the light power of a fensol focusing spot attachment, it is not easy to find out.

But these days, it has become quite fashionable (at least I think it has not gone out of fashion yet) to shoot on location, and underexpose the world and creat a stylised almost painted background. This requires more power then if you were just doing fill, and it is not always easy to work out house much power is enough for these types of applications, especially if you have a couple of strip boxes and a beauty dish each reducing the light power by a different amount.
 
FranchiseJuan said:
I guess the problem with deciding how much power you need is that many of the light modifiers don't specify how many stops you loose, and it is only in using them that you find out.

For example if you want to find out what is the effect on the light power of a fensol focusing spot attachment, it is not easy to find out.

But these days, it has become quite fashionable (at least I think it has not gone out of fashion yet) to shoot on location, and underexpose the world and creat a stylised almost painted background. This requires more power then if you were just doing fill, and it is not always easy to work out house much power is enough for these types of applications, especially if you have a couple of strip boxes and a beauty dish each reducing the light power by a different amount.
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Fair comment about the light loss due to modifiers. I think that some suppliers don't seem to believe in telling their customers anything, others are just interested in shifting boxes. Some though do give detailed info.

When it comes to light shaping tools such as fresnel spots, beauty dishes, focussing spots there is an actual loss of light that's easy to calculate. Diffusers though, such as umbrellas and softboxes, are less easy because the light is more spread than lost and there can be huge variations due to a number of different factors.

As for overwhelming daylight to create a dark background, I agree here, the problem is not only the variable brightness of daylight but also light to subject distance and type of modifier. I know that a lot of people use hotshoe flashes for this but frankly I don't know how they do it - I typically use a portable 600J powerpack and rarely have a great deal of spare power.

As I've tried to make clear in the guide, there isn't a definitive answer. Horses for courses etc. What I've tried to do is list the factors that affect the amount of power needed so that people can make more informed decisions.
 
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