Wide Angle Lenses and Focal Length

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.

If you’re coming from the camera phones and cheaper point-and-shoots, you probably don’t know about focal length or wide angle lenses. On the phone’s camera, you cannot modify these, and it’s fixed to “wide”. On the point-and-shoot, typically, the lens can go from wide to narrow.

When you’re shooting photos for Ebay, you want a wide angle lens. You’re shooting indoors, so you cannot get very far from the subject. If the subject is large, like an article of clothing, a wide angle lens can take a photo that shows the entire object.

Identifying if a Lens will go Wide

When you look at the lens, or the numbers around the lens on the camera: it never says “this is WIDE”. Instead, you see numbers like “24-104mm”.

That number is the range of focal lengths of the lens. The lower the number, the wider the lens. So you want a low number, down in the 15mm to 25mm range.

I bought a camera that came with lens that wasn’t wide enough, so I bought a second lens, an 18mm-55mm lens, which was the right size.

The old S110 has a lower focal length of 24mm, and that’s pretty good.

What the Numbers Mean

The numbers are called a “35mm equivalent”, and refer to an idealized sensor size that’s the same size as 35mm film, and an idealized lens.

The actual sensor is smaller, and positioned closer to the lens. In the DSLR I got, the sensor is 24mm (the Nikon DX sensor size). In the S110, the sensor is 14mm. The estimated size of the iPhone 6S sensor is 4.1mm.

  • One of my Nikon DLSR lens is 14mm to 55mm (35mm equivalent)
  • The old Canon S110 has a 24mm to 140mm lens (35mm equivalent)
  • The iPhone has a 24mm lens (35mm equivalent)

The DLSR is huge and bulky. The S110 fits in a jacket pocket or in a bag. The iPhone fits into a jeans pocket.

So, the cameras all have “similar” lenses, but the cameras vary in size because the sensor is smaller, and closer to the smaller lens.


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See Also

What happens when a full frame lens is used on a DX DLSR.

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