Equipment: Canon EOS-1D Mark III with EF 100mm f/2.8L Macro IS USM lens. Exposure: f/2.8 at 
second and ISO 250.
Training yourself to recognize and anticipate the decisive moment is the key factor in learning to shoot effective, artistic candid images. To really step up your game and sharpen your intuition to best capture people in their element, you must commit yourself to hunting these singular opportunities 100 percent of the time. When you go out on a shoot, you’ll need to adopt a new attitude, coupled with some preparative thinking.
Have you ever turned around while at a shoot to find your subjects hugging, with their faces all scrunched up, just aching with happiness, and missed the shot? Maybe you saw the embrace and reached for your camera but, once you wrestled it from its case, you found its strap was knotted around your arm and the lens cap was on. By the time you were ready to compose the shot, the interaction was over and the subjects had moved on. Had your camera been ready to go, prefocused with the lens cap safely tucked away, you would have got the shot. Instead of kicking yourself, you’d be patting yourself on the back.
Avoiding this kind of mishap is simple: just be prepared. Professional athletes don’t leave anything to chance. They do everything in their power to eat correctly, hydrate themselves, stretch, and warm up before the event. Photographers who want to take their artistry to the next level should adopt the same attitude.
For the best results, check your camera settings often. Maybe you changed your aperture during the vows and forgot to reset it when you went outdoors. Perhaps you turned your flash off for a long exposure earlier and are now preparing to shoot the first dance. You and I may scoff and call these rookie mistakes, but the truth is, something like this happens to all of us on occasion. Given that the odds are already against you, it’s a shame to let a simple, preventable error ruin the shot of a lifetime. So check those settings. Stick your lens cap in your pocket. Put your strap around your neck. Be sure everything is easily accessible and ready to shoot at all times.
If your subject is engaged in an action or conversation, zoom in and find your desired focal and cropping points.
Then, go a step farther and seek out your subject. Prefocus on them. If they haven’t arrived yet, focus on a person or object in the general area where you’re expecting them to be. This is especially important in a dark environment, as low light can cause autofocus lenses to operate slowly. Keep an eye on everyone around you while you’re making your preparations. People will be getting used to you being there and may start to ignore your presence. You’ll be able to snap off a few dramatic candids of the guests while you wait.
If your subject is engaged in an action or conversation, zoom in and find your desired focal and cropping points. The more accurately you can compose your image in the camera, the less you’ll have to fix later. Once your background is perfect, your cropping is good, and everything is lined up just right, don’t jump the gun. Keep your camera up and ready. When the decisive moment arises, you’ll feel it in your gut. When the subject is mid-laugh or just starting to tear up, you’ll be prepared to fire away. As photographers, we tend to look at the technical aspects: the shot looks right, it’s in focus, and no one is in your way, so you shoot. But consider how different the shot could be if you just wait.
Equipment: Canon EOS-1D Mark III with EF 70–200mm f/2.8L IS USM lens. Exposure: f/3.2 at 
second and ISO 200. Focal length: 200mm.