Product Photography: Getting the backdrop UNDER the subject pure white

[elaton]

Hello.

I am new to photography so this might be a beginner's question:

I am shooting products against a white backdrop, and I've had success with achieving a pure white background by putting lots of light behind the subject. However, the part of the backdrop on which the product sits is still showing up blue/gray (instead of bright white). If I increase the light in front of the subject that just washes things out (in case it helps, many of the products are white/ivory). (And the items I'm shooting aren't easily selected - e.g., fringed blankets - so correcting in PS takes a lot of time and often ends up looking unnatural.) So how do I get enough light UNDER the subject without over-lighting the subject? As a newbie, any information on where I should position the lights to minimize this problem would be very much appreciated.

[Mark1]

It might be a white ballence isue. If it is white it should photograph white. Or the background is not a neutral white. Your overlighting the background may overpower the color cast. But the light needed to light the subject is not.

There are a few things to try.

If you want the "floaty" look just get it as close to white you can and then just cut it out in photoshop and put it on a white baclground.

If you want it grounded. You can select the background in photoshop and desaturate it. Adjust it as needed to look right.

But I would look into te background. A true white should not shift color. Adjust the WB as needed and you should be good.

[elaton]

It might be a white ballence isue. If it is white it should photograph white. Or the background is not a neutral white. Your overlighting the background may overpower the color cast. But the light needed to light the subject is not.

There are a few things to try.

If you want the "floaty" look just get it as close to white you can and then just cut it out in photoshop and put it on a white baclground.

If you want it grounded. You can select the background in photoshop and desaturate it. Adjust it as needed to look right.

But I would look into te background. A true white should not shift color. Adjust the WB as needed and you should be good.

Thank you for those tips. However, I've played around quite a bit with the white balance (I usually set it using an 18% gray card), and shoot in RAW so that I can make additional white balance adjustments as needed. I want to avoid the completely "floating" look, plus when shooting things like fringed pillows it's hard to cut them out while keeping them looking natural. Even selecting the background in PS takes forever and never looks completely natural. As I mentioned, the background color is coming out properly, and the color of the subject is, too. I just can't seem to get the backdrop underneath/directly in front of the subject pure white without overexposing the subject.

I know it can be done (see, for example, this video (http://www.youtube.com/watch?v=Yue9BWbrb7g&feature=related)), but I'm not sure what I'm doing wrong.