I am a beginner in photography and starting to learn about lights in portraiture. In this portrait below, I am using a home-made soft box with a flash inside (on the right), and two 5000K bulbs at 1750 lumens (one on the left as a fill light, and one on the top as a rim light). Most of my stuff are home-made or DIY because I can't afford proper equipment. But I am trying to understand the basics as much as I can to replicate a proper studio setting.

enter image description here

Question: Although I have high lumen bulbs for my fill and rim, why aren't they filling up the left side of her face or creating a rim ? Even when I use my flash inside the softbox at lowest setting, it seems to overpower my fill and rim lights. What am I doing wrong ?

[Nikon D5200 f/5.6 1/100 38mm ISO-100]

  • 7
    Welcome to Photo.SE. Excellent first question!
    – scottbb
    Apr 25, 2018 at 4:41
  • Thank you :). I thought I understood light after learning lumens and white balance. But today I learnt about lumen-seconds. Great place to learn and understand ! :)
    – Santy.8128
    Apr 25, 2018 at 5:44
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    To be fair, that doesn't appear (to my non-professional eye) to be a bad picture, though it may not be what you're after.
    – FreeMan
    Apr 25, 2018 at 14:00
  • 2
    ^^ I think that's just the beauty of the model. :) :P
    – Santy.8128
    Apr 25, 2018 at 15:17

4 Answers 4


There is a substantial difference between strobe lighting and "hot" lighting when it comes to measuring light output.

You don't specify which flash you are using, so I'll use an SB700 as an example, which if memory serves is rated at about 30watts with a 4/1 efficiency compared to an incandescent. So let's call it 120 lumen seconds.

The difference between the two is the rate at which it outputs the light. You'll notice that I used lumen seconds rather than lumens. This is because a strobe will dump its entire charge in a matter of milliseconds, so the entire incident occurs while your shutter is open.

Hot lights, on the other hand, are generally measured by the light they output in a full second. So for your 1750 lumen output, only 1/100th of that light is entering your camera. That is only about 17.5 lumen seconds during the exposure time.

Compare this to a 120 lumen second output from the strobe, and adding in the inverse square law to compensate for distance, it's very easily over a stop difference between the maximum output of your hot lamps and the lowest setting on your strobe (which is consistent with your sample).

That being the case, you're probably better off working to master single light setups (with reflectors) until you can afford to upgrade your kit.

Back when I was shooting, I did a ton of my work single source. I found the limitation forced me to be more creative. For example, this shot imitates the type of three light setup you're attempting with a single light source (the sun) with 2 reflectors providing the "key" and fill.

enter image description here

  • 1
    Aaahhh I understand now. Great suggestions! One of my friends who is an amateur as well uses reflectors a lot. I thought since I can at least afford to buy high lumen bulbs, I should try multiple lights. But I will get back to playing with a reflector more. Thanks for the suggestion. And amazing explanation.
    – Santy.8128
    Apr 25, 2018 at 1:34
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    Reflector counts as light source. It's still 3 light setup.
    – Agent_L
    Apr 25, 2018 at 8:57
  • @Agent_L I have to respectfully disagree. A light source (as a self defining term) must be the source of light. Reflectors, because they do not produce any light, fail to meet the requirements to be considered a light source. There is only 1 light source in this image, the reflectors merely provide the illusion of two additional sources. Apr 25, 2018 at 18:50
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    @LightBender That is good definition - but in physics. In photography we don't care at all if it produces light or reflects it. What we care about is how the subject is lit by it, hence in photography "a source of light" we define as "something that useful light ultimately comes from". Eg, a bulb that lights the photographer but not the subject counts as "not a light at all", while the Moon counts as "source of light" for us even though we won't argue with grade school physics outside of photography. The atmosphere counts as source of ambient light. Up-flash is not a source, the ceiling is.
    – Agent_L
    Apr 26, 2018 at 8:28
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    @Agent_L I'd be very interested to know the source of that definition, I've never heard light source defined that way. Either way, I think we're talking at cross purposes on this one. The point I was trying to make is that you can accomplish a traditional "three light setup" without actually having to buy three lights. A very useful skill when you're starting out and have no money or have to shoot in locations that require a 30km hike over rough terrain. Apr 26, 2018 at 12:32

Nothing at all against LightBender's calculations and advice, but the OP's question is about balancing flash and ambient light, which is a valuable concept to tackle.

Check out this great how-to on the Strobist blog.

To summarize:

First, turn off your flash completely and find a good manual exposure for the ambient (hot lights). Then, dial that down a stop or two darker. Now bring up your flash. If it really overpowers the hot lights -- even in Manual at 1/128th power? -- you should be able to move it further away from your subject (and/or the hot lights closer) to achieve balance.

The other key point is that shutter speed uniquely controls ambient exposure without affecting flash exposure. In your example, going from 1/100 to 1/30 sec should brighten the fill/rim by a couple of stops.

  • This is a great suggestion as well. Honestly, at this stage I am trying to figure out what I am doing wrong. And understanding the idea of lumen seconds was very helpful. I will try the your method and see if I can improve results without having to buy better bulbs or another flash. Thanks so much. [PS My votes don't show up as I am new to this site]
    – Santy.8128
    Apr 25, 2018 at 5:46
  • 1
    This is the way to think it if your math sucks, like mine ;)
    – Tetsujin
    Apr 25, 2018 at 8:02
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    But but but, I am a mathematician by profession :( :( :P :P
    – Santy.8128
    Apr 25, 2018 at 18:56
  • @Tetsujin Come to the dark side... we have 𝝅 :) Apr 26, 2018 at 12:36
  • @LightBender - I love 𝝅, especially with ice cream... it's just so darned difficult to cut accurately into thirds... now was that degrees or radians... meh, I'll do it by eye... close enough :P
    – Tetsujin
    Apr 26, 2018 at 12:47

First let’s talk about the location of the “FILL”. The purpose of the fill is to soften the shadows cast by the main. Further we want to fill these shadows from the camera’s viewpoint. To accomplish, the fill is set at lens height as close to an imaginary line drawn lens to subject, as possible. Take care that the “FILL” is not so close that it will be imaged.

The fill light is subordinate to “MAIN” lamp. We take pains to force it to be one stop subordinate which yields a “bread & butter” ratio. The name comes from the fact that this 3:1 ratio sells best.

If the “FILL” is adjusted to be subordinate to the “MAIN” by 2 stops, the ratio is 5:1. This is a more contrasty lighting sometimes called masculine.

If the “FILL” is set 3 stops subordinate, the results are very contrasty sometimes called theatrical. The ratio is 9:1.

It is difficult with mixed lighting (electronic flash and hot lights) to make precise exposure determinations. Compose the scene, set the electronic flash as the “MAIN”, set high to simulate afternoon sun. With the “FILL” off take a shot and note the exposure. Now place the “FILL”. With the “MAIN” off, take a shot and note the f-number of the exposure. Back the hot light “FILL” testing to achieve 1 f-stop stopped down. Do the same for the rim light. The objective: Keep the “FILL” and the “RIM” light subordinate. Back the “FILL” or the “RIM” by measuring the distance lamp to subject and multiply by 1.4. This math calculates a revised lamp to subject distance that reduces the light energy 1 f-stop. Conversely, dividing by 1.4 computes a revised lamp to subject distance that increases by 1 f-stop.

  • That is a very detailed instruction. I will have to take some time to digest and understand the details and will get back on this thread if I have further questions. Really appreciate all the suggestions here. [PS My votes don't count because I am new to this site, but I am grateful for your pointers]
    – Santy.8128
    Apr 25, 2018 at 5:48

Probably what you're doing wrong is mixing flash with static lighting. If you need three sources, use three of the same type. No need for particularly powerful lights, I'm doing most of my work with a handful of cheap LED lights now - and I mean the REALLY cheap ones, not the ones that try to maintain the 'studio equipment' price point.

  • Yes, you are correct. I am realizing that now based on all the replies. Thanks for the suggestion.
    – Santy.8128
    Apr 25, 2018 at 16:24

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