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Can someone help me understand lens focal lengths and also the comparison between interchangeable ones and P&S?
For example, if a pancake lens is 20mm f1.7, does that mean it is wider angle than the Panasonic LX5 (a point and shoot) which has a lens of 24mm and f2.0 (with about 4x zoom)? Or is there a conversion factor when comparing?
What measurements would be considered wide angle, telephoto, and fast for interchangeable lenses? Do they compare the same for point and shoots?
1 Answer
- B.E.I.Lv 71 decade agoFavorite Answer
As far as comparing DSLR lenses to a P&S, there are a lot of variables that you need to consider. It is like comparing apples to oranges to fruit punch. As far as your lens question, it would depend on the camera you put the 20mm lens on.
Different DSLR cameras have different "crop factors" (magnification in simple terms). A Nikon D3x and a Canon 1D (and 5D) are "full frame" sensors, a 50mm lens is 50mm on them. Other DSLRs have a 1.3x or a 1.6x factor sensor, a 50mm on them is equivalent to a 65mm (or an 80mm lens respectively). The other thing to consider is the sensor type and size itself. A full frame DSLR sensor is 36.0mm x 24.0mm, a 1.3x sensor is 28.7mm x 18.7 mm, and an APS-C(1.6x) sensor is about 22.3mm x 14.9mm versus a P&S sensor of 5.75mm x 4.31 mm (numbers from various Canon cameras).
The aperture (or f/stop) is what determines how "fast" a lens is. The lower the f/stop number, the faster the lens is, meaning the lower the f/stop number the wider the aperture opening allowing more light in to the sensor.
