How to acheive a pure white background in a lightbox?

[BEphoto]

I home built a lightbox a month or so back to do some product shots for some friends' website.

It is constructed of:

Cardboard box with two windows covered with vellum
two 500w worklights as the light sources
White posterboard as the backdrop

Heres a quick shot i took to show it when i first put it together, just for reference sake.

http://farm4.static.flickr.com/3573/3321635523_e9443ca052.jpg



So, my problem is that my background never comes out pure, solid, bright white. I even shot the lightbox with no products inside of it and used that as the custom white balance, and it still comes out a tad grey or has a hint of whatever color my product is. They look great on my LCD at the time of shooting (and i keep my LCD at the halfway mark, not blown out turned up all the way), but as soon as i get them home the grey comes out.

Here is an example of how they look, straight out of the camera. Only RAW conversion to JPEG done.

http://farm4.static.flickr.com/3600/3449603758_a3e51c5459.jpg





Now, i figured it should be as easy as clicking the background either in DPP, or in PS to set as my white point and that would fix it. Well, it doesnt really. I want the backgrounds pure white, where on a white page you cant even see the edges of the image.

So, the only way i knew how to do this was to just dodge the entire background until it was completely white. That works great for the most part, but getting around the edges of the product get tricky, and you get discoloration when the brush hits. I set my dodge exposure to highlight, then only put the exposure at around 13% or so.

This is the look I get using my method, and pretty much what im going for from the get-go.

http://farm4.static.flickr.com/3357/3448796229_5b08193199.jpg


It looks great for the most part, IMO, but you lose some detail where there are highlights around the edges of the wheels when you run the dodge brush near them.



So, in conclusion here, how can i get this look straight out of the camera? I would love to avoid my dodge method at all costs. It just takes too dang long to go through 200+ products and do that to every single one.


Not even sure if this is the right section to post this in, but any help you guys/gals could give would be great! I've got some similar products to shoot soon and would like to get it right the first time if possible.

Thanks again in advance.

[Karl Johnston]

I think its a great DYIer

I've been wanting to get a lightbox/build one

[vincent_su]

Although I've never used a light box I do know the pure white background without details needs two elements.
1) over exposure of the background, 1/3-2/3 stop.
2) distance from object to background to prevent wrapping.
For a light box setup like you have, I would try to add one more light from the top and blocking the light source so that it only light up the background.
Use a larger box will help as well.
Hope that helps.

[Hermes]

Use a strong light from the back and place the products on a sheet of reflective material like plexiglass to ensure that the surface beneath them also blows out. This will be the most practical way with the setup you have

[silvrr]

A better initial exposure will allow you to use the click to set the white point method. Light your background from behind and overexpose 2/3 stop. From there adjust as needed after the first shot to control the exposure but get the background as white as possible. Adjust the products position and light position to avoid blowing out the subject and go from there.

When I had my LB setup I could get it really close in the exposure and use the levels or curves eye dropper to make the background totally white.

[BEphoto]

Great advise here. So, should i use a sheet or something transparent for the background rather than the posterboard. I cant really light that from the back. I liked the look of the posterboard because its completely seamless so you dont get wrinkles or anything like that.

Would it be better to just shoot the box empty until the background blows out completely and just lock in my exposure there? Im very new to using artificial light. I've always done natural light portraits and speedlight stuff. Never anything with constant light sources, so i had no clue how to meter. I realize now that i think i was metering for the product and not the background, trying to be sure the product is exposed properly. Also, i may have used Av rather than just setting the exposure in manuel once and leaving it. I was thinking that Av would give me a proper exposure every time, but now i see that my logic was completely off on that one.

When i get home today i think im going to play with it a little more until i can get it closer straight from the camera. Both times i have shot for these guys has been pretty much spur of the moment so i havent had much time to work with it before shooting.

Thanks again for the suggestions. Anything else you guys wanna add, go right ahead!

[silvrr]

Great advise here. So, should i use a sheet or something transparent for the background rather than the posterboard. I cant really light that from the back. I liked the look of the posterboard because its completely seamless so you dont get wrinkles or anything like that.

If you blow it out you wont have to worry about the wrinkles as much. Also make you box deeper and use a shallower DOF to help blur the background which will aid in making any wrinkles dissapear. You could also try thin paper.

Would it be better to just shoot the box empty until the background blows out completely and just lock in my exposure there?
Its really a blancing act. What makes the background all white may overexpose your subject. I prefer to setup the exposure with the product in the box.,

Im very new to using artificial light. I've always done natural light portraits and speedlight stuff. Never anything with constant light sources, so i had no clue how to meter. I realize now that i think i was metering for the product and not the background, trying to be sure the product is exposed properly. Also, i may have used Av rather than just setting the exposure in manuel once and leaving it.

Pick a aperature and adjust your shutter speed in manual. I find that works best. I dont think the camera really wants to make the pictue you are taking in this case so best to leave Canon's logic for a good exposure out of the picture..

I was thinking that Av would give me a proper exposure every time, but now i see that my logic was completely off on that one.

When i get home today i think im going to play with it a little more until i can get it closer straight from the camera. Both times i have shot for these guys has been pretty much spur of the moment so i havent had much time to work with it before shooting.

Thanks again for the suggestions. Anything else you guys wanna add, go right ahead!

It always takes me quite a few shots before I get the lighting correct. And then you can put something else inside the LB and need different settings.

[BEphoto]

It always takes me quite a few shots before I get the lighting correct. And then you can put something else inside the LB and need different settings.

thanks a lot for the response. Also, what type of lenses work well for this type of work? I used my 70-200 f/2.8L IS for all of these because the size of each product was varying and I figured the zoom would be easier to work with than moving my tripod around if I used say, my 50 1.8.

Kind of thinking the 50 may have been better now though, for one because if the larger aperture, and two, the shorter minimum focus distance would give more blur and maybe get a little more detail out of the shots.

Again, thanks very much for your input.

[silvrr]

Either one would work. Your not really going to want to open up either of those all the way. 1.8 and 2.8 would provide a pretty shallow DOF and Im guessing you would like most of the product in focus.

Again just play with it. Try taking your cam off the tripod also. adds alot more room for creative angles.

[dadohead]

Use drafting vellum to make the sweep. Roscoe makes a very heavy roll plastic for exactly this purpose that's even better but probably a little harder to find. Then pump some light from the back to match whatever the lightbox is putting out. Move the utility lights on the sides to match. You could also think about a little top light, rather than the on-axis strobe on the camera. This will help punch a little detail into those black wheels.

The problem is the size of the box. When you light up the back, you'll start getting some lightening around the edges of the products, especially with partially transparent items like these skate wheels. You could fix this with a bigger box (MUCH bigger). If you are doing anything reflective, you'll eventually just wind up buying a Cocoon or tent; however you can also accomplish this in a pinch with a cone or cylinder made from the drafting vellum with a hole cut in it for the lens.

Having said all this, you'll always get a better shot after a little work in PS. It's hard to accomplish fully in camera without a studio full of gear.

[jrsforums]

Get the exposure right for the products.

Then in PS, open a Level adj. leyer. Move the white arrow (the one on the far right) to the left until the background is the way you want (I doubt you want "pure white, probably a little short of that).

If your "products" have white in them you may need to mask the levels adj.