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gilbill Feb 23, 2007 8:50 PM

I want to take a portrait with a lighting ratio of 1:2. I understand to do this if I have my key light at f11 then my fill light needs to be f8. I am using an AB400 synced to my camera for my key light and a 60W halogen light with a reflector for my fill. I have a light meter so adjusting my key light to f11 is no problem. My question is how do I get f8 out of the halogen light. Is it distance from my subject? Do I just keep moving it away until it reads f8. And then my other question is how do I meter it if I can't sync it?

These are probably really simple questions but I am still trying to figure this all out and I know there is a lot of knowledge out there.

Thank you so much anyone out there for your help.


wass Feb 23, 2007 10:45 PM

You have to remember that moving your light away from your subject will alter the intensity but will also alter the "quality" of light. The further away from the subject the smaller the light will appear, and the harsher the shadows.

Maybe the easiest would be to put something in front to the light to put something in front of the halogen. If you do this with a sheet then you will increase the "size" of your light, then moving the light and screen away from the subject may be what you want.

You have the AlienBees B400?

If so are you shooting B/W or are you wanting the color differences.

gilbill Feb 23, 2007 11:03 PM

Thanks for answering me. I am using an AlienBees B400. I have a huge sheer reflector I can put in front of the halogen light. Now my other question is metering that light. Do I meter the reflected light?

I am probably going to shoot all color, I have a Nikon D50. I will post process some to B&W I'm sure because I will be shooting an 8 1/2 year old girl and her 6 month old brother.

Thanks again for your help.


wass Feb 23, 2007 11:35 PM

When the light is falling on the main subject you would take an incident reading. If you are wanting the background reading then you would use reflective.


I'm not a pro but I have taken some classes. I hope this works out for you.

Ronnie948 Feb 24, 2007 8:05 AM

What ever you do :::: DO NOT::: drape anything over the halogen light, They get very, very hot and a fire can be caused by getting anything to close.


gilbill Feb 24, 2007 8:30 AM

Thanks you guys! My subjects will be here in about 3 hours. I'm so excited and nervous. If anything turns out I will post it.

Wass, what classes have you taken? On line or university ones. I need to find some good classes to take. Boise State has some classes but I don't think I can afford the time or money so I'm thinking on line.


amazingthailand Feb 24, 2007 8:01 PM

You have Alien Bees B400. Good lights. To set your light ratio you can do one of two things.

First, using a FLASH meter, you can measure the output of each light independantly. Adjust the output of the main (fill off) until you get the desired f value you want. Then (with main off) adjust the fill until you get the desired f value you want.

Now with both on, you have your desired lighting ratio.

Second, if you do not have a flash meter (hightly recommended, by the way), set up you main light until you have the desired output. Now on the fill, adjust the output slider until it is reduced by one f stop from the setting on the main.

I use the first method. You should also use the histogram function on you camera to check the overall exposure prior to starting in on your portrait session.

What I do is get my subject to sit or stand at the point where you will be shooting them, and I make a number of test exposures with my camera, checking the histogram to be sure all is within range (you really cannot do this by just looking at the image on the LCD). I make minor adjustments (usually the f stop) until I get it where I want it. Then just shoot and forget the lights.

If you use your subject as a test subject, explain you are just making final exposure adjustments prior to starting the session. Or use a friend/assistant prior to the arrival of your subject.

Okay, I just read the rest of the postings. You have only one B400 (correct?) and are going to use a 60W halogen light for fill.

This won't work unless you really want a big color difference in the light from the main and the fill. Also, the B400 is VERY powerful especially when compared to a 60W lamp. You will not be able to get the fill ratio you want with such a small light. You really need TWO strobes. The strobe (B400) will completely overpower the halogen.

When I shoot, I also shoot video simultaneously and I have 5 strobe units and three 750W halogen lights set up. The halogens are overpowered by the strobes by a large margin and do not show up as a factor in my still images.

gilbill Feb 24, 2007 11:35 PM

Wow, thanks amazingthailand. A lot of helpful information. I know I need to learn to read my histogram because I cannot trust my LCD. And I did notice that shooting without the halogen and with my AB400 behind me seemed to work okay. What I don't get is I take a meter reading say 1/250, 200 ISO and my meter says f11 is right. So when I shoot at f11 my picture is way over exposted. So I shut my light down to 1/4 so that is reads f5.6 and set my camera accordingly and my picture turns out great. Why? You know it seems so simple, you set up a couple of lights, get a subject and shoot some great pictrures. Not so easy. But it sure is fun learning and makes you feel so good when you finally get a good picture.

I will save up and buy another AB400so I can get a little more creative. But until then I will keep working with what I've got.And with all of the useful info you all have given me I will have lots to work on.

Thanks so much!


amazingthailand Feb 25, 2007 10:03 AM

You didn't say if the meter you are using is a flash meter or an incident/reflected light meter.

If the latter (reflected light) and you are trying to meter the B400, all you are metering is the modeling lamp. The strobe output is considerably more intense and that is why you are over-exposed and why you must use a flash meter when using strobe lighting. A flash meter will measure the strobe output and give you the exposure for the strobe. The modeling lamp output is dwarfed by the amount of light the strobe puts out.

But get to know your histogram. In your case, setting up a studio strobe (without a flash meter) it will act as your meter telling you how your exposure is. Bunched to the right is over-exposed, while bunched to the left is under-exposed. You want to 'expose to the right' without overdoing it.

Like the old joke goes: How do you get to Carnaige Hall? Practice, practice, practice.

For additional information on the histogram and it's use, see this article at Luminous Landscape:

and this:

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