A guide to photographing items without a background and using focus stacking to keep the entire object in focus.
Sometimes one just feels like Cervantes’ knight, flailing away at our windmill. Everyone I care about insist on using their dishwasher to clean their good knives. This, despite all the experts telling them not to do it. Well just, look at this knife!
There is a back-story here. I spent two hours photographing this knife to show how damaged it was. Do you know how many times this knife could have been washed by hand in two hours? Well since I have the photograph let me tell you how I accomplished this. You will note the knife does not have a background and note the knife is in focus for its entire length. Product people love to get photos without a background since they can place the photo in front of any background.
We cover the technique for getting a photo without a background in this post and we will cover the focus issue in a latter post.
To obtain the knife without a background we used two procedures. The first is to photograph the knife with a white, blown-out background. Then the photo was later adjusted in Photoshop. If the first step is successful, the second is fast and easy.
To obtain a blown-out background you simply have to overexpose the background and correctly expose the subject, i.e., the knife. How to do this? There are most likely several ways but I know one and I only know it in theory. This is my first attempt and I now explain it.
We want the background very bright and we set our camera to photograph this background and overexpose it to a degree that it has no information in this area. The histogram of such a photograph would look like this:
Photographers try to avoid this normally. To try this on purpose is unusual. The second aspect is to photograph the knife at the same time with the correct exposure. This is my approach. Set up a white background and light it from both sides with bright lights. The Kelvin temperature of this light is not important. Photograph this background, setting the camera f-stop, speed, and ISO in manual mode so that the background is blown out. Be sure your speed is 1/200 or less since you need the camera to synchronize with a flash. Now place the knife on a pedestal in front of the white background, the greater the distance the better since we do not want light to spill onto the back of the knife and wrap around it. Now take the photograph. Check your histogram for detail from the knife or chimp your camera’s screen. You can no longer change the camera settings so adjust the flash output power. The setup is diagramed below.
When you are happy with the photograph, you can process it in Photoshop.
In the next post, we will show how to use focus stacking to achieve a fully in-focus knife in our extracted photo. Until then…