From this photo you can see the midway position of the weight. As you can see from the position of the hands, they are wider than the shoulder width. There is a good reason for this. The closer together your hands, the less the pecs work and the more you bring the triceps into play.
Bench presses use a number of secondary muscles including deltoids (shoulders) and triceps, part of the arm. You have to be very careful when you train that you are focusing on the right muscle - the chest (pecs) muscle. If you do not get your mind right, the smaller weaker muscles like the triceps will think they are the ones being trained. You will finish the training not really getting the most out of the chest training. It is also very important to remember that if you train triceps on the same day as you train chest, always train the chest first. If you train the triceps first then they will be too fatigued to be able to get a proper chest workout. I have often had people tell me that they get tired in other places instead of the chest. It is because the focus is not on the muscle being trained.