Metering for strobe ratios without a meter

Hey,

Looking to use my studio lights for the first time at the weekend. I've used some similar before, I understand how to work them (as in triggering them, how the change the settings etc)

My plan is to have a key light to one side (45 degrees I suppose) with a softbox on, then a fill light through an umbrella towards the front. Then I plan on adding a background light and possibly rim light just to see how they change things. I also have some gels and a honeycomb to play with.

On the courses I've been on and the videos I've watched I think I have got my head around ratios, meter the key light, meter the fill light appropriately and then away you go.

However, I've just realised I do not have a light meter, how do I use the camera to do this - when I've used one light it's easy to experiment to get the exposure correct when looking at the histogram.

Thanks in advance, and if I've got anything wrong please tell me!

Also, I shall be photographing a 1 year old, two 3 year olds and a 6 year old - all of which are cousins. Any tips for poses and prop ideas would be gratefully received!

Thanks again.

You really cant measure ratios without a flash meter. I suppose you could shoot a gray card with the various lights on to see the proper exposure from each but even then it would be a fuzzy approximation. Assuming your lights are the same, and your modifiers reduce the power a similar amount you can use the settings to get close (provided the lights are the same distance away. But the reason they invented light meters was so you dont have to use those assumptions. You probably just want to eyeball it at this point.

gonzogolf wrote in post #16393660
You really cant measure ratios without a flash meter. I suppose you could shoot a gray card with the various lights on to see the proper exposure from each but even then it would be a fuzzy approximation. Assuming your lights are the same, and your modifiers reduce the power a similar amount you can use the settings to get close (provided the lights are the same distance away. But the reason they invented light meters was so you dont have to use those assumptions. You probably just want to eyeball it at this point.

Thanks, I figured as much. More money to spend!

I bought a Sekonic L308S the other day and I could NOT be without it now. It's probably one of the most important (to me) pieces of equipment I have purchased. Simple things like being able to check background uniformity make it so much easier. I usually meter my key and fill but rim lights I just play around with to get the right look. One thing I do hate having to do though is pop my strobes on the skyport whilst holding the meter...........

dbeugel wrote in post #16393695
I bought a Sekonic L308S the other day and I could NOT be without it now. It's probably one of the most important (to me) pieces of equipment I have purchased. Simple things like being able to check background uniformity make it so much easier. I usually meter my key and fill but rim lights I just play around with to get the right look. One thing I do hate having to do though is pop my strobes on the skyport whilst holding the meter...........

I think that's the model I was looking at. Cheers.

Another quick Q. I have three lights, one key, one fill and one background. Will one be enough for the background? Assuming I'm trying to blow out a white background? It will obviously be off to one side of the background, should I just set it so high that there's no notable fall off of light on the other side?

sancho1983 wrote in post #16393716
I think that's the model I was looking at. Cheers.

Another quick Q. I have three lights, one key, one fill and one background. Will one be enough for the background? Assuming I'm trying to blow out a white background? It will obviously be off to one side of the background, should I just set it so high that there's no notable fall off of light on the other side?

Its very difficult to get an even spread across the width of a background with a single light. Part of this is due to falloff, the closer you get to the subject (in this case the backdrop) the quicker light falls off. Because of the nature of the setup, background lights have to be close to the drop and therefor tend to have a stop or more falloff across the drop. In theory you could blow it out so that regardless of falloff you get white across the spread, but if you do that you will likely have so much light wrap from the white drop bouncing on the back of the subject you get flare and reduced edge sharpness.

Here is an example of the falloff. Its on a gray drop with a single bare speedlite right behind the subject, you see how quickly the gradient shows going from bottom to top? If the flash was farther from the drop is would have been less dramatic but its still a factor.

Thanks, it's good to have examples as well. I have a couple of yonghuo speedlites so I suppose I could try to balance the background a bit with one of those?

The children I will be shooting are my family, 2 children are mine and the other 2 are niece/nephew. This will hopefully be a good chance to try things out without a lot of pressure. I'm sure it will be crazy, but hopefully will learn a lot.

The Sekonic L-308S is not capable of measuring the ratio between ambient (constant) light and the light from a flash unit (or units). The L358 does this, however, and it can be very useful. My understanding, though, is that the L358 is not being produced any more. I haven't done the research to see what replaces the L358, but it seems that you can buy them used.

If you have identical lights and understand the inverse square law, you can get pretty close with the ratio.

If your key is 4 feet from the subject and the fill is 5.7 feet from the subject, you'll get one stop less from the fill and a 2:1 ratio (assuming identical lights at the same power setting and similar modifiers). Move the fill back to 8 feet and it'll be 2 stops less for a 4:1 ratio.

The hard part is figuring out what ratio you really want. If you're indoors with a white ceiling then you'll get plenty of bounce affect that will lower the contrast. With high ceilings or outdoors it's a whole different scenario.

Curtis N wrote in post #16393752
If you have identical lights and understand the inverse square law, you can get pretty close with the ratio.

If your key is 4 feet from the subject and the fill is 5.7 feet from the subject, you'll get one stop less from the fill and a 2:1 ratio (assuming identical lights at the same power setting and similar modifiers). Move the fill back to 8 feet and it'll be 2 stops less for a 4:1 ratio.

The hard part is figuring out what ratio you really want. If you're indoors with a white ceiling then you'll get plenty of bounce affect that will lower the contrast. With high ceilings or outdoors it's a whole different scenario.

That makes sense.

Will be indoors with a high ish white ceiling. Not sure what ratio to use, I suppose 2:1 would be ok seen as the subjects are young?

Shoot tethered.

And shoot tethered!

pyrojim wrote in post #16393783
Shoot tethered.

And shoot tethered!

I don't know whether that will be another thing to worry about or not. What are the advantages?

sancho1983 wrote in post #16393772
That makes sense.

Will be indoors with a high ish white ceiling. Not sure what ratio to use, I suppose 2:1 would be ok seen as the subjects are young?

Or you can just set the identical lights the same distance away from the subject and adjust the power level of each accordingly, for the ratio you want.

set up a white target, shoot your main such that it's just below producing blinkies.
then shoot your fill, power it up to just below blinkies, then, like Leo said, drop the power down by what ever you think you want your ratio to be.


Joel Grimes doesn't meter, only chimps
http://www.youtube.com​/watch?v=Xvj2l4lBeis

dbeugel wrote in post #16393695
I usually meter my key and fill but rim lights I just play around with to get the right look.

Hi, I have the Sekonic L308S too and understand you use incident metering. Do you point the light meter to the camera or to the light source?

Thanks