Cokin Grad Filters

[RobbieW]

Hi

I have a cokin graduated ND4 filter, which is the equivatalent of -2 stops. If I buy a ND2 (-1 stop) filter,a nd put them both in the filter holder will this be the equivalent of a ND8 (-3 stops) filter?

Are there any disadvantages to do this?

Thanks for any help

Rob

[chrisiow]

The main disadvantage is extra layers of glass in front of the lens, its got to degrade the image to some extent.

[Jimmy_Lemon]

I have done the same before and in some shots it works, but if you have sunshine hitting the lens it can cause very nasty reflections inbetween the filters and you can either end up with reflections of your lens or just odd lines of yellowness :(