Photography help! White backgrounds?

I'm wanting to photograph kids with white backgrounds. I have a Nikon D40 and was wondering how to go about it with just the camera. Do i use a white sheet and the camera flash or photoshop etc.
your help would be greatly appreciated!
:)

White sheet, whitewashed wall, whatever you have to hand…

a camera flash will not spontaneously change a background colour…

Light the wall a stop or two brighter than your subject

If you are talking about high-key shots, you'll need more than a white sheet to achieve good results… Some form of lighting (I use Bowens 400/750 W/S strobes) is a necessity to light the background, and separate lights to light the subject. Your on-camera flash will cast a shadow on the white background and the lighting will be harsh and uneven.

If you have a white background (BG) make sure that your BG is further from the subject specially if you're going to use a flash on camera. This is to prevent cast shadows on the white BG. Try experimenting with bounce flash too.

Without flash be careful and make sure you meter your subject using spot or center weighted mode. Using multi segment metering might underexpose your shot because your camera might read the larger white BG. ☺

You need to know about lighting if you are taking on portraiture work - don't think you can just do it all in Photoshop.

You will need more than your on camera flash too - a 2-3 light setup plus modifiers (softboxes and/or umbrellas) are required to soften the light. You can go wired (mains) lights or battery operated speedlights (handy for location shooting). You will also need some means of triggering the flash from the camera - either a wired (PC cord) or wireless (radio trigger) solution.

It is possible on occasions to work with natural light only - but you run into problems when it's not enough, or in the wrong direction and you client is waiting…

Best to learn about lighting first - a good online resource is the Strobist blog - start with Lighting 101 & 102. The video also gives an idea of the gear you need to set up.

As for a white backdrop - again you have a choice of material - muslin, paper & vinyl. All have their advantages and disadvantages. To get a white background you light it 2-3 stops higher than your subject.

It depends on the equipment that you have. If you have professional lighting and backdrops then use them. If you don't you can make do without, but it won't be as easy and setting the flash and snapping the picture.

If you only use the flash from your camera you will cast a heavy shadow on the background that will show up in your picture. To get rid of this you will need to have your kids step away from the background and have a light behind them. Even a lap would be better than nothing. You might need to adjust the angle or position to get the best lighting for your picture.

If you are just using a white sheet, you might want to double it up so that whatever is behind it won't show through.

Once you are happy with your picture, take it to Photoshop and edit out any shadows or spots that you couldn't take care of with the lighting.

A white background is created by blasting tons of light at the background and then exposing the shot correctly for the subject.

If you don't have some off camera lighting then you'll have to cheat a bit.

If you have a patio door that gets lots of light, hang your white sheet in fronnt of it (light coming in through the back).

Switch your camera to manual mode. You'll need to use spot metering and meter for your model (kids) and use your popup flash to fill in your subject. You need to use the built in light meter to gauge your exposure correctly.

Be aware that this won't be perfect. It's no real replacement for a 3 light shot with poroper seemless paper and softboxes but it will get you close enough if you are just doing this for fun.

Here is an example (no fill flash and not true high key but you can see what the blown out curtains look like):

The image above was shot purely wiith the light coming infrom the window. The window had a gauzy, white drape in front of it.