I know next to nothing about cameras (other than how to push the shutter button). Up until a few days ago I thought of zoom as simply a multiple (e.g. my Canon S95 has 3 or 5X optical zoom) and had no idea what these millimeter values were.
I'm starting to read about focal lengths and more advanced measurements, but the explanations are not that intuitive to me. I think I'm getting it, and it would help if I could get confirmation that what I think is actually correct:
- focal length of our eyes is about 50mm (or is it 35mm? I have seen both numbers). So if a lens has a 50mm focal length, it will take a picture roughly of what I can see with my eyes.
- less than 50mm is considered "wide angle" because it's essentially "zoomed out" of what I can see with my eyes
- the amount of zoom (in standard point and shoot speak) is the ratio of the longest focal length of a lens to the shortest. Some lenses have only one focal length (fixed) and thus no zoom
- a telephoto lens has a large focal length (how long though?)
- the Canon SX510 HS has a 24mm lens, and a 30X optical zoom, so thus its longest focal length is 720mm. This should zoom to about 10X what my eye can see.
Is what I've written above correct?