Ive started out focusing on landscapes, then added pet photography. Started with the 24-105 F/4 and learned I need to add the 24-70 f/2.8 for pet photography and some indoor events. I plan to get the 24-70 within the next 6 months. However, on my christmas wish list is the Singh Ray vary ND. Since the two lenses have different diameter sizes, and I can buy ONE of the filters... Im wondering which lens should I buy it for? So far, Ive used the 24-105 for landscaping with good results, but am wondering If you were given that choice, and wanted to use the Vari ND, which lens would make more sense to use it on? I understand losing stops due to the light, so in my mind starting with 2.8 seems to make sense. Wanted to pick your brains. Thanks