I had ordered a BTP x3 6stop ND filter and had hoped to take it with me on my last trip. There was a delay in production and it was evident it wouldn't be here before my departure. Because of that, i hastily chose a replacement filter. Knowing Singh Ray is based out of FL and not being able to decide on which level of ND filter to buy, i purchased a Variable ND filter from them. It arrived quickly and i was able to take it with me. Unfortunately, i was un aware of it's shortcomings with regards to vignetting when using a wide lens. Because of this, a 2 - 14 stop filter is only good up to about 6, maybe 8 stops. In day light at F22 this only allowed for 4 to 10 second exposures which wasn't slow enough for the effects i was going for.
I decided to keep the order for the BTP 6 stop filter thinking that i could stack it on the variable ND which should allow for 30 second exposures in bright daylight. So now i have 2 ND filters in 77mm and i just upgraded my most used lens which will now require 82mm filters. ugh....
So i've ordered a BTP x3 10stop ND filter. I figure that should handle most situations and when looking for longer exposures in the evening or dawn, i can utilize a cir polarized filter to gain a few stops. Which i'll also have to repurchase because outside of the newest ND filter, ALL my other filters are 77mm.
I guess most people are used to having different sized filters and i was just probably spoiled by having all of my lenses use the same size filters for the last 10 years. Oh well, i guess i can use the filter size issue as a justification for upgrading my other 2 lenses.