Kristy mentioned over on her blog that we’re trying to purge ourselves of some of our excess stuff. Part of that means finding things that have been in boxes for a long time and getting rid of them, either by donating them, or, if they seem salable, by putting them up on eBay.

One thing that I do, when buying from eBay, is try to find an auction with a crappy cell-phone looking picture, or, better, no picture, and as little descriptive text as possible. These ones get missed by more searches and overlooked by more bidders, and as a result, I spend less money. So of course, to maximize our take from the items that we’re going to try to sell ourselves, we’re trying to do the opposite. And part of that means getting *nice* pictures of everything we want to sell.

What is a photographer with little equipment to do? Worse, what is a photographer who has pledged to forego discretionary spending to do? Why, construct a lightbox-alike for cheap, of course!

We had a white sheet that we’d purchased to project on (unfortunately, the day we wanted to project on our patio, it was quite windy, so the sheet was in pristine condition). Fortunately, among my equipment, I do include a few un-substitutable essentials: a tripod, a reasonably advanced digital camera (I am overqualified in this area). I also have a nice fast lens, which helps get rid of pesky backgrounds, and a totally-overpriced gray card. A word about gray cards–they cost so much because they’re supposed to last. But if you have a decent color printer and don’t mind reprinting one every month or so, you can use this handy one I threw together in Photoshop (more details about what it is, what it’s for, and how you use it later on).

1. Controlled lighting
2. White sheet
3. Tripod and camera
4. Gray card

Setup

Even with a tripod to help you out, you still want a reasonably bright light source; however, to save time, try to make sure that the light source isn’t going to change while you are shooting (light from a window is bad for this). To make it easy to reach your work surface, I recommend working up on a table. To give yourself enough room to work, the table needs to be relatively deep. Finally, you need to be able to attach a white sheet behind your work area, and the sheet needs to be long enough to drape down to your table surface and cover it. The sheet should be draped loosely, not forming a sharp angle where it meets your work surface–otherwise you’ll get strangely shaped shadows. Pictured at right (or above, depending on how this text lays out) is the arrangement I used. If you can arrange for your light to be coming in at a 45 degree angle, it will produce some nice shadows for you. I know that in a real lightbox, you try to completely eliminate shadows, but that isn’t going to happen for us.

1. Work table at comfortable height
2. Hang sheet behind, curved gently from vertical to horizontal
3. Light at 45 degree angle

Getting Started

Turn on your light source and walk away for at least five minutes. This is especially important if your light source is a CF bulb or (ugh) a fluorescent tube. The light will change as the source warms up, so just let it sit for a few minutes. Before we start shooting and every so often while we’re shooting, we’ll be metering to make sure we take the best pictures we can.

Before we start shooting, there are a couple of steps to get your camera ready. The first thing you should do, whatever camera you are using, is set the ISO value as low as your camera will permit. Higher sensitivity lets you shoot in lower light at faster speeds, but it adds a lot of noise to the picture; and we’ll have a tripod, so shutter speed is immaterial for our purposes. Once your light source has warmed up, take your camera off the tripod, bring it over to your work surface, and haul out your gray card. Almost all cameras have a feature that lets you adjust the “white balance”–this is how the camera compensates for the fact that most light sources are not pure white. The first thing you’re going to do with your gray card is set this white balance. The process varies from camera to camera. With my D70, I hold down the WB button and roll the primary selector until PRE is selected. While holding down the PRE button, I press the shutter release. On my SD400 point-and shoot, I press Func/Set, choose “CUSTOM” white balance, and then press the menu button. Check your manual for details. For this part of the process, you want to be pointing only at the gray portion of the card. Your camera may have a hard time focusing at close range; if manual focus is available, use it. If you have a viewscreen, you should see the colors of things around you abruptly change; if you have an SLR, snapping a few shots should show you quite a difference.

The next thing we’re going to use the gray card for is to figure out the best exposure for our photos. Sadly, many point-and-shoot cameras aren’t flexible enough to let you perform this adjustment on the camera. If you’re using one of them, instead place the gray card in the middle of your workspace and shoot a couple pictures of it. Try to make it take up about 1/4 of the frame in at least one of the shots and about 1/2 of the frame in another. We’ll use these later in Photoshop to correct your images. If you have an SLR, however, we can actually figure out the correct exposure settings using your card. Put your camera in aperture priority mode; after selecting the aperture you want to shoot at (I recommend f2.5 if you can), shoot a frame containing only the gray card, again probably using manual focus. Note the shutter speed the camera uses; then abandon aperture priority mode, and put the camera in full manual mode with the aperture and shutter speed from the previous step. The metering logic in SLRs will try to perfectly expose this “18% gray” value. A final note about exposure: when shooting photos in this style, I prefer to overexpose by about “one stop” of light, to help blow out any background details that may escape our shallow f2.5 depth of field. On my SD400, I do this by setting the “Exp” value to +1; on an SLR, you would do it by setting the shutter length to twice the value obtained from the previous step (so, for example, 1/40s -> 1/20s).

Please note that if you’re shooting on an SLR, I highly recommend that you use RAW mode. If you should overexpose an image too greatly, it can usually pull back at least half a stop of detail more than if you had been shooting JPG.

Place your camera back on your tripod and start shooting. If you are using a point-and-shoot that doesn’t let you manually adjust aperture and shutter, try to make the object you’re shooting fill as much of the frame as one of your test shots with the gray card; that will make color correction easier. In either case, remember to repeat the procedure above every hour or so to make sure that the light has not changed too much on you.

1. Let the light warm up
2. Use the lowest ISO setting available
3. Set the white balance on your camera using the gray card
4. SLR shooters, use aperture priority to figure out correct exposure with the gray card, then MAKE SURE to switch to manual
5. If you can’t adjust the aperture and shutter independently, take several test shots with the gray card to help with correction later
6. It might be a good idea to overexpose slightly, especially if you shoot RAW anyways. If you are unable to shoot in full-manual mode, you must overexpose

Shooting

Because we are working with (probably) an artificial light source from around the house, and because we’re actively trying to overexpose the image we produce, the shutter time is likely to be rather long; at anything longer than 1/60s, hand shake is likely to be visible in the image, and even if you are using a tripod, pressing the shutter release will likely cause some jitter. If you have a remote release, you should use that; and if not, you should use the self-timer feature. Set it to the minimum value (2s on my SD400), and use the 2s it provides after pressing the shutter release to gently let go of the camera.

Work as quickly as you can to prevent the light from changing too much on you. I recommend a brush to dust your work surface off if you are photographing items that have been in storage; if the bristles are soft enough, you can use them on the item itself. Keep in mind that if you attach any additional filters, such as a polarizer to cut reflections or a close-up lens to capture details, you should repeat the white-balance and metering steps; anything in the light path will change the light received at the sensor.

When you are done shooting, drink a beer.

1. Use a tripod
2. Use a remote / cable release if you have one
3. Use the self-timer feature if you don’t have any better option
4. Redo the metering and white balance whenever the light changes
5. I like a nice weiss beer

Post-Processing

If you are fortunate enough to be shooting with an SLR, you should have very little in the way of post-processing to do. Congratulations–the extra $374189 that you spent on your camera is paying off today The image at left came directly from my camera with no color correction whatsoever–just the RAW processing, but that’s a part of my workflow by now. What’s great is that if I’d followed my own directions (I didn’t–I left the camera in aperture priority mode, a big mistake) all I’d need to do at this point is crop. Because I left some of the exposure decision up to the camera, quite a few actually needed the kind of adjustments that the exposure section is meant to avoid.

If you’re shooting with a point-and-shoot or if your camera otherwise restricts your ability to control exposure, you still have some work cut out for you. The white balance should have removed any color casts, a particularly difficult problem to solve in image processing software, but there’s still the question of making sure your levels are where they should be. Because cameras try to expose “18% gray” correctly, photos that are mostly white tend to get underexposed–it thinks the white should be gray, see?–so you’re going to have to do what you can to correct that.

An important tool in post-processing is the histogram. You might remember histograms from that stats unit that sometimes happened toward the end of the year in math cla–WAKE UP BACK THERE–class. Histograms show the frequency of each of a discrete set of values. In image processing, the values are usually luminance values, and the histogram is to show you how much of your image has a particular brightness. At right is the luminance histogram of our sample gray card image, as I produced it on my computer. Notice the small spike at far left to show the region of the image that’s pure black, the small spike at right for pure white, and the large spike for “mid gray.”

The goal here is to, using the levels tool, find the adjustments that restore your photo of the gray card to the correct brightess.  Once you’ve done that, write down the levels settings that you used, and apply them to subsequent images.  This should resolve any brightness problems you may have.