. What would I need to fit a filter to my Nikon 18-200 VR which has a 72mm diameter.
Is it just the Cokin adapter and then the filter?
Is there a specific adapter for 72 mm lenses and does it need to be of a specific width to accommodate the '18' end of the 18-200 range to avoid vignetting?
Why did you suggest that specific graduated ND filter?
ok ignore if you know this -
the "cokin" or similar system consists of 3 bits
the filter
a holder for that filter
a fitting called an "adapter" to fit the holder to your lens
so, working backwards
you buy a 72mm adapter [eBay] and screw into the filter thread
you buy a holder to suit filter size [more later] and slide onto adapter
holders have 3 slots to hold 3 filters
this makes then "thick" so a wide-angle adapter is available so you dont vignette at 18mm - the WA holder only holds 1 filter
then you buy a filter - and chaos begins cos there are a zillion available
so time to do some Google searching
there are 3 sizes/widths A P and Z
you will need "p" series for your lens i think
thus you buy a "p" series holder
I'm just beginning - here's where i got sofar
a ND filter - this cuts down light across the WHOLE frame - loved by togs to slow down lovely rivers so they look like milk......


the higher the number the more light it cuts
or Grad ND used to cut back the exposure in the sky usually
you slide the filter up/down in the holder to match the horizon
on landscapes use a soft grad to blend with the hills
on seascapes can use a hard grad which cuts right across the horizon
grads are designated 0.3 = 1stop, 0.6 = 2 stops, 0.9 = 3stops
i just started off with a couple of 0.6 grads
hope that helps...............
