相機既 chop factor

It should be " crop factor ", not " chop factor ".

When compare to 35mm film camera (what we called " full frame "), some DSLR can also provide the " full frame " sensor but some cannot.

For example, Canon 1Ds is full frame (no " crop factor ", or you can say " crop factor = 1 "), Canon 1D Mark II has 1.3 crop factor (that means when you put on a 50mm lens, it becomes to 65mm), Canon 350D (your camera) has 1.6 crop factor (that means a 50mm lens would become 80mm).
Some lenses are designed for 1.6 crop cameras only and cannot be put on to 1.3 crop or full frame camera bodies. You have to make sure if the lenses can be fitted on to your camera!