I apologise for not responding to your post yesterday, unkyUb.......the old brain shut down when my BP went awry.
Glad to see that roseway has posted a comprehensive reply to your points.......and I would agree with all he has said.
As to the polariser.........first of all, yes you can still attach the hood but there may be problems depending on which thread the hood screws onto.
If the hood normally screws into the filter thread on the front of the lens, no problem as there is a same sized thread on the front of the filter. That all assumes that your hood is round, if it is square or petal shaped at it's front end, you couls possiblt get the cornes of that front end intruding into the scene.
If, however, the hood screws onto it's own thread elsewhere on the lens then you have a problem in that the hood will prevent access to the filter and thus prevent you rotating it for effect.
In that case you would have to adjust the pola. then attach the hood.
I realise that budget constraints are influencing you decision....but in all honesty I would place a ND Grad before a polariser on the priority list.
Lets go back to your earlier question about which filter to use for a seascape.
OK, you see your scene and think "great, on with the polariser and saturate the colours...also it will knock out the reflections from the water. No reflections so I can see the seabed, and capture that lovely white sand under the water...or use the same pola. technique at rock pools...eliminate the surface and snap the crabs and thinks creeping around on the bottom. And to boot get a lovely blue sky"
But........there is a snag. The sky, as discussed earlier in the thread, is very much brighter than the foreground and when the foreground exposure is right you may well get a washed out sky. The polariser will not correct that imbalance.....it will attempt to saturate that sky but if the sky is burned out to such an extent that there is no detail there, then there is nothing to be polarised.
The polariser will not balance foreground and sky........for that you want the ND Grad.
Conversely, the ND Grad will balance but not saturate the image.........so what to do to achieve both effects ? You use both filters together ! !! and that is why the square filter system in a holder is the better option...much easier to use.
However that costs money, so let us try to economise........by not getting the polariser. For those on a budget, let us not forget that we are talking digital photography here...and the effect of the polariser can be achieved in any good, free image editor simply by pushing up the saturation and contrast levels.
