All three zoom out to 300mm i.e. that is the maximum magnification. The 70 – 300 has a zoom range, the minimum vs. maximum is 300 ÷ 70 = 4.28. The 55 – 300 has a zoom range of 300 ÷ 55 = 5.5. The 70 – 300 has a zoom range of 300 ÷ 70 = 2.28. The difference is the span of the zoom from minimum to maximum. All three have the same maximum zoom but the minimum magnification is different. Two have a minimum focal length of 70mmm, one has a minimum focal length of 55mm.

All three zoom out to 300mm i.e. that is the maximum magnification. The 70 – 300 has a zoom range, the minimum vs. maximum is 300 ÷ 70 = 4.28. The 55 – 300 has a zoom range of 300 ÷ 55 = 5.5. The 70 – 300 has a zoom range of 300 ÷ 70 = 4.28. The difference is the span of the zoom from minimum to maximum. All three have the same maximum zoom but the minimum magnification is different. Two have a minimum focal length of 70mmm, one has a minimum focal length of 55mm.