Zoom lenses were created to be a prime lens’s versatile counterpart. If you want to show more in a photo, you zoom out. Of course if you want to have a tighter field of view, you zoom in. But there’s an additional zoom you've had all along, it is called Foot Zoom (jokes aside, if you do not have feet then whatever way you have to physically move your body and camera farther or closer from the subject will work). An example would be taking a photo of your significant other. In this make-believe but entirely possible scenario, you’re in a restaurant with light from a bulb shining right on their face. You pull out your camera, since you carry it everywhere like a good photographer should, zoom all the way in on their face and take a photo. The photo then comes out grainy and blurry!
But wait, Image Stabilization?!
Hold your horses! Zoomed in, the maximum aperture has become smaller and the camera has had to compensate by raising the ISO, or how sensitive it is to light. Also, the shutter speed may have been slower so the smallest movement from the subject would cause blur (IS is for your shaky hands, not someone’s shaky face).
Now, you will learn this tried and true technique. Set your camera to Aperture Priority, zoom all the way out, and set your aperture as wide as it will go. Slowly zoom in until you see that the aperture changed to f4. Take the photo again. You’ll notice two things. First, there’s a lot more of the scene. Second, the photo is slightly less grainy and not blurry. Now three things are coming into play: you’re zoomed in, causing your aperture to be at f5.6. At f4, you’re letting in twice as much light (1 stop). You can also have a slower shutter speed because the wider you go, the easier it is to stay steady (1 stop due to longer shutter speed). So roughly two stops gained translated to your ISO dropping about two stops, resulting in a cleaner image. Lastly, you took a photo of your significant other in the context of a scene. You might see other people eating, sunlight bursting in through windows, or perhaps a waiter/waitress taking someone’s order. This makes for a much more interesting photo.
These were taken by my wife, Cecilia. The first is at ISO 6400, 55mm. The second is at ISO 800, 23mm. even at almost the highest ISO, the first photo isn't even that noisy at this size (click to view at 700 pixels on its longest side). With that said, you get a better idea of where we're at and what I'm wearing. A little bit more 'story,' you could say.
The upcoming post will be about thinking in terms of light, shadow, and shapes.