Ef-s focal length

ross attix wrote:

If you are a beginner and have gotten through all the discussion of this topic and have come to this understanding you are doing really well, and you are correct.

The difference between sensors on FF cameras, vs APS-C in the case of Canon, is simply cropping.

Think of it this way-A lens is simply "projecting" an image onto the sensor. Using the same lens to subject distance a 100mm lens will project the same size image on any body. If you aimed it at a coin, and the coin image measured 1/4 inch on the sensor, it would measure 1/4 inch on any sensor.

The FF body has a bigger sensor so there is more room around the coin; the crop body has a smaller sensor so there is less room around it.

--
Ross Attix