ND split filter for widefield and AFS nikkor 14-24/2.8

[chrismalin]

Hi there,

maybe some of you doing widefield astrophotography / and or using cokin filters in the past have an idea?

I am searching for a ND split filter like this hoya

http://www.hoyafilter.com/products/hoya/oef-08.html

but in form and shape like a square glass-plate, which is bigger in size than the diameter of the huge frontlens of the AFS 14-24/2.8. I'd need such a filter to dim the lights of cities in the valleys below on days where there is more saturated, haze air, which you can see in my video here.

http://newswatch.nationalgeographic.com/2011/05/26/new-mountain-timelapse-a-soundgarden-of-night-lights/

If I am able to dim the city lights better I can show more sky (thats a nice application of a split ND filter). I have seen some astrophotographers in the past holding glassplate split ND filters in front of their wide angle lenses per hand just for the long exposures, but at that time I failed to take exact notes what they used.

for stills I use a pice of paper or sometimes the back of my hand, but for timelapse it would be handy to have a true ND filter.

thanks for any hints.

sincerely

christoph