In the previous post, we discussed ISO, Aperture, and Shutter Speed. We had just taken a photo with a fast shutter speed and everything was perfect!
Well not so fast. Remember when I mentioned that the key to a perfect photo was getting the correct Exposure Level or the correct amount of light into the camera Sensor? Well just because you set the Shutter Speed to 1/150 sec, doesn’t mean you allowed enough light into the camera Sensor. It is actually possible that the photo may be to dark, especially if the photo was taken late in the afternoon, when the sun wasn’t at it’s brightest. So the real question is, “How do I allow enough light into the lens to the Camera Sensor to make that perfectly sharp photo?”.
You have to ensure that when you set the Shutter speed to 1/150 of a seconds that the aperture is open (big) enough (small number) to allow enough light into the camera sensor can take the picture with out it being to dark. Now it is possible that you set the shutter to 1/150 and the Aperture to 2.8 and the photo is still to dark. So the next step could be setting the ISO from 100 to 200 or even 400, to allow enough light into the camera sensor to talk that perfect photo. Now Remember, I mentioned that little thing called “Depth of Field”. If you make your depth of Field to shallow because of a setting of 2.8, then only a very small section of the photo may be in focused.
Lets imagine that you are on a Football field at the Goal Line and we setup a three football players on the field. The 1st at the 10 yard line, the 2nd at the 20 yard line and the 3rd at the 30 yd line. If we focused at the 2nd player, and our camera settings were at ISO 100, Aperture 2.8, and Speed was at 1/150 sec, then the 2nd player will be in focused and the 1st and 3rd players will be out of focused. This is because I have a very shallow depth of field. Now if I set the ISO to 800 and Aperture to 11 and Speed stays at 1/150 sec, and I focused at the 15 yard line, I would probably have the 1st and 2nd players in focus and the 3rd player out of focus. The reason that both the 1st and 2nd player are in focus, is because I split the difference between them and because my depth of field was deeper, I was able to bring both of them into focused. If I wanted to bring all three players into focus, I would probably need to increase my Aperture to 22. Unfortunately, if I leave my ISO to 800 and Shutter to 1/150 sec, everyone might be in focus, but it will probably be dark. so i’m going to have to increase my ISO to 1600 and have noise in my photo or I’m going to have to lower my shutter speed. This now can possibly cause motion to occur in my photo. The other thing I can possibly do, is increase the amount of light by using a Flash to ensure that I let all three players have enough light to still make a sharp photo.
Now I used the football player example on purpose for a couple of reasons. One there was a football field and I had some known distances, but also because you probably know that football players are never still. They are in motion either running with the football or running to tackle the person with the football. To capture motion, we are going to have to increase the speed of the shutter to probably 1/250, 1/500, or even 1/1000 of a second. this will make the photo even darker unless we use one of the techniques to adjust Aperture or ISO, or add additional light. It is important to make sure you have enough light coming into your camera to take a photo no matter what the subject matter is. In a later section I’ll talk about buying faster glass (lens) or better camera bodies to help improve these things.
The first techniques you have to master is to determine if enough light is coming into the camera to capture that perfect shot. The picture to the right is the Exposure Level you will see in in your view finder on the camera as you look through it. There is a scale that has a minus (-) sign on the left and a positive (+) sign on the right with a 0 in the middle. By changing the Shutter Speed and and Aperture, you want the little lines on the bottom to move toward the center spot or near the 0. When you get the Exposure Level set to ‘0’ the photo will be set correctly to take the photo. Now, once you see these settings, you are going to have to make some decisions.