Lens Aperture and Shooting Indoors

If you’re a camera novice, like me, all the numbers around the lens, and in the camera descriptions, are really, really confusing. They were basically meaningless to me, until I needed to shoot photos indoors; and they mattered for online sales on Ebay.

Photos are captured by exposing a sensor in the camera to light. If too little light gets to the sensor, it’s a dark picture. If too much light gets to it, it’s a overexposed or bright white picture. You want just the right amount.

Cameras have two ways to control the quantity of light: aperture and shutter speed. Aperture is how large the shutter opens, and shutter speed is how long it opens.

For indoor photography, you want the maximum aperture to be as large as possible. In the camera (and lens) specs, this is identified by the “f” numbers. These are called the “speed” of the lens, and you want a “fast” lens.

  • f1.8 : this is very large, the max for Fujifilm XF1
  • f2.0 : also large, the max for the Canon S110
  • f2.2 : not so large, but still good
  • f2.8 : typical of expensive “prime” lenses for DLSRs
  • f3.5 : typical of zoom lenses for DSLRs included with camera kits

Typically, you will see the numbers indicated like this: “f1.8-5.6”. That specifies a range, with the lower number being the maximum size aperture, and the higher number being the smallest size aperture. You don’t really care about the higher number.

The other thing that affects lens speed is the amount of “glass” (really, plastic) in the lens. The more lenses you have, and the thicker the lenses, the less light gets through, and the “slower” the lens becomes. That’s why the big DSLR lenses are slow, and why point-and-shoot lenses are faster.

The faster the lens is, the faster you can set the shutter speed.  The faster your shutter speed, the less likely you are to introduce camera shake blurring. The main way to avoid shaking is to use a tripod; the problem with tripods is how they limit the photos you can take. You also need to spend money to get them, and you won’t use them too often.

The faster the lens is, the less time and money you need to spend on artificial light kits. I use a cheap LED lightbulb setup that I got from the hardware store. It’s great for the cameras with fast lenses, but just barely adequate for the DLSR.

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