Converter question

[Eric Mc]

Ok...so theres something been bugging me for a while now.

A 2x converter I can understand....doubles the focal length of your lens....200mm becomes 400mm ect

But 1.4x....why? Why not 1.5x so 200mm becomes 300mm ect

 

[mmcp42]

because everything photographic is based on the square root of 2 = 1.4(14)
look at apertures 8 5.6 4 2.8 2 1.4 (1!!!)

1.4 = 1 stop

 

[DiddyDave]

Also, there no such thing at 'ect', you mean 'etc.'

Other than that, what he said ^^^