I'm thinking of getting a macro lens.

I've noticed that the minimum focal distance is around 20cm (at the lens i'm looking at).

I've also noticed that some come with a 1:1 ratio, and others 1:3.

My question is, 'is there much of a difference from the 1:1 ratio as there is to the 1:3?'

At the moment i'm looking at these ones

Tamron SP AF90mm F/2.8 Di Macro Lens
Sigma 18-50mm F2.8 EX DC MACRO /HSM Nikon Mount
Nikon AF 60mm Micro 60 f/2.8D Lens

But i'm just a bit confused.

So if someone could shed some light, that would be greatly appreciated.


TIA