Hey Mike,

Great question. As with anything else, the big question is about application, right? I.e. until you get the 24-70 and know how it feels and looks at different focal lengths, you won't really know which lens you will use more often. There are trade offs with both lenses - certainly if you look at them from just a paper perspective.

What are your other lenses? Are the 77mm filter sizes or a different size? That may also impact your decision on which filter to buy (i.e. most of my lenses are 77mm, so it makes it easy to buy one set of filters for all lenses).

If you need to buy today and cannot wait, there is a sloppy short term fix that might appeal to you. I am thinking on the order of using a step-down ring for the larger lens (the 28-70). The problem with that is that you are sitting the filter further away from the lens and may cause vignetting - particularly at the wider ends of the spectrum...otherwise, I might consider waiting a bit.

Congrats, BTW, on the variable ND. It is a definite 'want to have' filter from Singh Ray.

James