One thing that I do frequently with my photographs is I use a combination of a wide aperture and a long focal length to decrease the depth of field (DOF) in my images to add more compression to the background, making it soft and out of focus. When photographing this cake pop I thought I would create some photos that show how different aperture settings can affect the background of an image.
The photos above show the final photograph along with a behind-the-scenes image. (For the final image I actually merged two files together … one at ƒ/4 to get a soft background, and another at ƒ/11 to get sharper focusing on the cake, since I wasn’t happy with the focus quality on the cake at ƒ/4). For this setup I used window light, bounced onto the subject with white foam board. For the background I used Christmas-tree lights in front of a soft yellow-ish cloth-covered piece of foam board to add more gold tones to the background, and bounced some light on it to make it a little brighter (that’s the foam board you see attached to the boom stand). The cake pop was about three feet from the background lights, and the camera was on a tripod (that funny-shaped black thing in the image on the right) approximately four feet from the cake pop. The DISTANCE you put between the subject and the background, and the FOCAL LENGTH you use (longer is better) are important if you want to achieve a very soft, out of focus background like I did here in this image.
The photos below show the same setup with different apertures, starting at ƒ/4 and going all the way to ƒ/32. All images were photographed at 200mm on a Canon 7D with no change to anything except the exposure settings. (To see it “in action” I created an animated GIF so you can watch the changes happen quickly.)
BTW, here’s a link to the recipe I used to make this cute little guy.