One of the most important factors in how good a photo looks is the focus. It doesn’t matter how great a subject or the lighting looks in the photo, if the focus is off then the photo isn’t worth keeping.
- Modern DSLR cameras used with SLR Booth Support at least 3 focus modes:
- Phase detection auto focus
- Contrast detection auto focus
Some new cameras such as the Canon 70D and 7D mk II support a hybrid auto-focus, but we’ll concentrate on these three main types.
Phase detection auto focus is the standard focus system for DSLR cameras. It is very fast, and quite accurate, but only works with the camera’s mirror down. When SLR Booth is running and showing a live-view preview, the mirror is up, so if this method of autofocus is used the camera must drop the mirror to focus, perform auto focus, then raise the mirror to take the picture. This flipping of the mirror up and down adds a bit of shutter lag and noise, but results in fast, accurate focus.
Contrast detection auto focus is used by DSLRs when running in live view mode. It is typically slower than phase detection to lock focus, but it doesn’t need to move the mirror. So while focusing is slower, there is less shutter lag. Some cameras will also do automatic face detection in this focus mode, which can be very helpful for a photo booth.
Manual focus is done by the photographer, rather than the camera. The benefit to manual focus is that there is no shutter lag, and you get consistent focus between shots. The downside is that your subjects have to be in the same place each time for this to work. Luckily, in a photo booth setting, this is actually pretty easy to accomplish. If shooting with a crop-sensor camera with at 24mm, and the apeture set to f/8, set the focus point to 6 feet and then everything between 4 feet and 11 feet will be in focus. Just place a mark on the floor 6 feet from the camera, and have the subjects stand there.
Personally, I only ever find myself using phase detection and manual focus: Manual when using a foot-pedal trigger, and phase-detection otherwise. Just remember to change your shutter delay in the settings when switching between focus modes!