how do I get a perfect white background?

Foxtrot_01 · Oct 3, 2012

Hello all,
I've been using a white backdrop for some shoots, I am trying to get a white background, I have two 285Hv's at full power shooting at the back with the model aprox 6 feet from the background, I am getting some light spilled onto the model so I am using some flags, still I am getting the center of the backdrop white and the corners dark. Should I use more then two 285Hv's? How to I go about getting a white background with off camera flashes?

cgipson1 · Oct 3, 2012

sounds like you need to move the flashes out a bit.... they are concentrating the light in the center. That will also reduce the amount of light splash. you might also try the wide angle flash adapter (can't remember if the 285's have those built in or not)... or a modifier of some sort that will spread the light wider.

Derrel · Oct 3, 2012

1-Read the Zack Arias tutorial on white background shooting. It is VERY helpful!

2- AIm the flashes in from the sides of the seamless, so you get an even illumination on the paper.

3- If the 2 285's cannot make the paper pure white, then LOWER (yes, lower. aka reduce) the flash power that the MAIN light is firing at.This is called key-shifting. it will "elevate" the background to white, by increasing the differential in exposure ebetween the background and the subject.

4- In a really confined space, some blowback or wrap (the spilled light you mentioned on the models) can happen quite easily. Shooting on light gray paper actually helps a lot. Gray is very easy to elevate to white, and it reflects less than white, so it really helps cut down on blow-back or wrap on the back sides of the people.

Foxtrot_01 · Oct 3, 2012

thank you for your prompt response and advice. The backdrop material is not paper but white muslin. the 285Hv head has a manual zoom from 35 mm to 105 mm, and can go down to 28 mm with the wide-angle lens.

@cgipson1 - thank you for the advice, what kind of modifier do you suggest?

@ Derrel - thank you for the tips, I will read Zack Arias tutorial, I have the two 285Hv's aimed from the sides at about 2 feet away point towards the center.

I also have another question, I use a beauty dish with a 285Hv on a 45 angle, I am getting light to the face and the torso but the feet are dark, any suggestions? should I switch to a soft box instead of the beauty dish?

Big Mike · Oct 3, 2012

I have the two 285Hv's aimed from the sides at about 2 feet away point towards the center.

Move them farther away if you can. The farther away they are, the more spread out, and thus the more even the light will be...but the background will also reflect less light as you move the flashes farther away...adjust your exposure settings and main light accordingly. Also, take care to position the background lights so that they don't overlap too much in the middle of the background. Take a few minutes of just taking test shots of the background until you find the best position for them.

I also have another question, I use a beauty dish with a 285Hv on a 45 angle, I am getting light to the face and the torso but the feet are dark, any suggestions? should I switch to a soft box instead of the beauty dish?

Once again, this is an issue of light spread. If the beauty dish is only lighting up the top of the model (but you want the whole body) then you have to move the light further away. A beauty dish does tend to constrain the light a little bit, a softbox may be worse but an umbrella would likely spread the light out more.

One of the problems with using flashes instead of studio strobes, is that they don't have a lot of lighting power, especially when you use modifiers....and when you have to move them further away, to get the light spread that you want...they may not have enough power. You are just going to have to be creative.

KmH · Oct 3, 2012

Moving a light further from your subject does 2 things

reduces the amount of light power that reaches your subject (Inverse Square Law)
makes the light source apparently smaller making shadow edges sharper, and harsher.

A beauty dish isn't intended to light a subject from head to toe. Light modifier size on the main light should be about the same size and shape as the subject you are wanting to light.

For a full length portrait a main light modifier would be a tall rectangular shape. Westcott 4839 54" x 72" Shallow Soft Box with Carry Bag, Only 20" Deep.

A single 285HV even used at it's widest setting will be hard pressed to light a full body shot regardless the light modifier used. The only hope would be to turn the 285HV sideways so the long axis of the flash head is vertical.