grad nd filters

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In the process of choosing a mattebox with 4x4 trays. One issue is how many filter trays to get. Most come with two with only one rotating. The rotating one is most important with nd filters.

When I shoot something with sky in it even at the beginning of the day and particularly at full sun I find that there is a difference of at least 3 to 8 stops. I was thinking of getting some grad nd's say a 2 and 4 stop one and stacking them if I needed more filtration power. What do you guys find you give you the most flexibility?

Also do you buy your gradations sharp or gradual? Is it better to get the nd part extending 3/4 of the way down the filter before it goes clear again. This way you can adjust how much of the nd part covers your scene by sliding it up and down.

What is the thickness of most of the 4x4 filters? I'm in the process of asking formatt and schneider but would appreciate anyone who can quote me some. One mattebox has a tray of 4mm thickness so if the filters are 2mm I can stack two together on one rotating tray. Is this possible?

Lastly glass 4x4 are quite expensive. Are there any alternatives like gel ones? I assume they would be alot less durable.

Sorry for so many question. As you may or may not know I live in Australia where no shop is keen for you to try any gear.

thanks

 

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Re: grad nd filters

Well guess I'll answer myself on this one. Spoke to Paul Stephens who runs the Formatt factory in the UK and he reckons I should go the route of the 4x5.6 panavision size filters. They can be inserted in a vertical manner (as opposed to landscape) so that I can adjust where the transition line cuts and still have the filter edges not being in the field of view. He said to stick with the nd being half the filter.
Formatt can actually custom make you grad nd filters which impressed me.