Nice white background using two speedlights

scottduffy

scottduffy

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Guys i have two yn465 flashes and i'm looking at creating a white background for some head and shoulders portraits tonight. I will be using a cream coloured wall and i was wondering if i should use both lights to blow the background or one light on the background and one on the subject with the background light being set at a higher power?

I was also wondering if i should bother with soft box/umbrella for the background or just have the speedlight on the stand bare.
 
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Have a look at Gavins middle item Grey Backgrounds- Quick shots no.8

Gavin Hoey makes loads useful videos.

http://SPAM/3azjz4h
 
Thanks John. I forgot about good old Gavin. I like his videos too. They're very simple to follow and produce good results without too much equipment. I'll give it a go.
 
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This was shot with one Speedlite on the background (white vinyl), firing through barn doors, and one Speedlite on the subject, reflected from a white umbrella. I think the background was on half power, so there's something in reserve, especially as I was at f/9 and 100 ISO. The only editing is to the skin. I have not touched the background or made any exposure adjustments.

20101020_145516_6108_LR.jpg


The background is not quite fully blown, but would be an easy fix to make.

Here I've used Lightroom to dodge the background a bit, but still not taken it to full white all over. I tried full white but it looks a bit "funny".

20101020_145516_6108_LR.jpg
 
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Hi Tim,

Thanks for posting that image. It's exactly what i'm after. Not sure if you've used the YN flashes but from most of the tutorials i've read it says the background light should be two stops higher than the subject light. I will start off at 1/2 power on the background and 1/8th on the subject and see how it goes. The cream wall should not be too much trouble to turn white i hope.
 
Scott, they're not talking about the power setting on the flash units, because there are other variables such as modifiers used, or not used, and distance of the flash head from the subject or the background. If you have a zoom head then that's another factor that upsets the apple cart.

What they are talking about is how bright the light is that is hitting the subject and the background (not the light coming out of the flashgun), and you measure that with a flash meter. Even then, if you have a white background then you only need the background to meter at may 1/2 to 2/3 stops brighter than the subject. If you have an off white or cream background then you might need a bit more. Without a meter (or even with, if your background is not white) you will need to experiment.

I think lighting the background at 1/2 power is a good starting point, allowing you the option to turn up the wick if you need to. As for the key light, if you're going to pump that through a softbox you will lose a stop or more through that, so I suspect you'll need to be at 1/2 power into the softbox too. Then jiggle to taste as necessary. If you let some light from the softbox spill onto the background it will do no harm in helping brighten the "dark" side of the background if you are only lighting it with one flashgun,
 
If it's not too late, you can get away with just one light on the background for head shots, as Tim demonstates. I find the best way to adjust the background brightness is to set up the front light, and then turn up the background until the blinkies (highlight over exposure warning) just (and only just) begin to flash. You may then want to turn down the main subject light a bit, depending on how much spill you've got bouncing around and filling in from the background, but that's the principle of it. Fast and easy.

Tim, was your background light on the left? There's a bit of flare showing. If your background light was not too bright (hard to judge with a blonde subject) then you could maybe fix that with a really hood lens hood. I use one cut from a rectangle of black card which exactly matches the field of view. It makes a difference.

Edit: Tip - when using hot shoe guns, at full power the recycle time is painfully slow. Shooting at half power halves that time, and at quarter power it's really quite quick. You might want to lower the f/number or trade a bit of higher ISO to get that.
 
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Richard, the background light was to camera left, but protected from causing flare with a spill kill and barn doors. I see the effect you're talking about and I think it is wrap rather than flare. The lens was my 70-200/2.8 IS and had its own hood fitted.

I don't have the original file with me at the moment, but I don't think the background was especially hot.

EDIT : I've now got the original raw file. Here it is with no alterations, so blown in places, but obviously not outrageously so....

20101026_081516_.JPG


I'm not sure what I could have done to reduce the "wrap" effect. I had limited space to work, a background that was much larger than I needed, and the lighting was metered to achieve what I thought was a correct balance. Actually one idea that occurs is that I used the barn door to keep the background light off the subject, but not to prevent spread over the unused portion of the background. If I had tightened the spread over on the left it would probably have reduced the wrap effect.

Oh, just remembered, I had a reflector on camera left, providing fill and acting as a gobo between the camera and the background light, so really no chance of flare at all. Maybe the fill is a little strong, but the subject wanted a shot that was sympathetic to her skin. :)

I don't have a setup shot for the image above, but here's an idea of the working environment, shown here with ~1.5m of grey muslin rather than the 2m width of white vinyl I used above.

20101013_133900_1075_LR.jpg
 
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Thanks for that Tim :) Just to add some comments really.

I think the main problem, if there is one, is that your subject is blonde. It just makes this kind of lighting so much more critical. There is a hot spot on the left, and the background is much wider than it needs to be.

It looks like both flare and wrap to me. Compared to the right hand side, on the left there's more light on the background and on the subject too. The background is much wider than it needs to be, which adds wrap and lots of bright flare-inducing light outside the image area. This is what a really tight lens hood would cut out, and if your 70-200L 2.8 has a shortcoming, it's probably flare. It's far from bad in this respect though obviously - you should try this kind of shot with a nifty-fifty :eek: I won't be doing that again!

But the flare you have there is localised, and not the kind of veiling glare that lens hoods are most effective with. It's usually down to the lens not handling the very bright area behind so well. Note it's absence on the right where the most significant change is the brightness of the background.

Thanks for posting the info, always interesting :)
 
I would just use one flash on the b/ground and one on the subject. I found that I need some kind of mod on the flashgun to stop too much light coming fowards out of the flash and hitting the subject. your going to get some coming off the background, but you don't want it from the flashgun.

I have used a peice of card to stop the light moving forwards when I have done this.

You will need a fair amount of trial and error to balance the lights, without gettng too much wrap around.
 
I think it's just a hot spot on the left Tim. Looking at the diagram, it could easily be one stop higher left to right. That's enough to over cook it with blonde hair ;)

I find that blinkies are a far more accurate way of assessing the evenness of the background light than a meter.
 
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