[LargeFormat] Filters

[Clive Warren]

At 2:12 pm -0700 7/7/02, Brock Nanson wrote:
huge snip
>The real advantage to using glass is durability.  I really hate having to
>use Cokin and the other 'soft' materials as filters.  I'm always concerned
>about damaging them, scratching them when they require a dusting, etc...
>I also don't like the potential for light to get in behind them and cause
>unwanted reflections and otherwise lower contrast.  That can't happen with
>screw on filters.  However, it's impossible to do any graduated ND work
>with a screw on filter!

The optical resin filters are surprisingly tough - it's the same 
material used for a lot of contemporary lens elements, although 
whether it is used for a front or rear outside element on pro lenses 
is another matter.

If you buy dyed in the mass filters then a small scratch does not 
remove the filter coating as it would with a cheaper filter. If the 
filters are shaded from direct (sun) light then there are not any 
noticeable issues with light spill behind them.

Optically they are probably superior to polyester - which is usually 
coated with filter material or surface impregnated.

Cheers,
        Clive