Not sure about the vignetting on film for the 18-55, but I did the test with the 16-45 on the Z1:
http://www.pbase.com/mattmatic/smc_da_test

Might help...
Matt

Pretty much ditto niblue here...
My wife's *ist-Ds has the 18-55 and takes acceptable images. But, the 16-45 is clearer through the viewfinder, faster at focus, and generally sharper.
But then it's a lot more than £29
As niblue says, if you haven't got anything else, the £29 is well spent... and you'll probably recoup that if you need to upgrade later
Matt

NP:
http://www.great-landscape-photography.com/graduated-filters.html
http://www.earthboundlight.com/phototips/neutral-density-and-graduated-nd.html
http://members.aol.com/kevinoneil/nd.html
http://www.bythom.com/filters.htm

That should keep you busy for five minutes
Matt

Ideally you should spot meter between the two halves and work out the exposure difference. The goal is to bring the brighter parts within the range of the darker area... but not too much (you don't want to lose the tonal range).
There are a few guides online I've seen... might be able to Google one out for you if needed

Yes. Generally I don't bother spot metering - I'll just look at a scene and guess on the ND grad, take the shot and review on the LCD (checking the histogram and exposure). If necessary I'll change the ND grad and shoot again.

...one of the wonders of digital

Matt

I didn't mean those!

I almost always use ND grads, and sometimes use a polariser.
Of course, with the Cokin you can use polariser and one or two ND grads (or just an ND if you want to slow things down in bright light).
Matt

I used to use the Hoya Pro filters - which are expensive, ultra thin, and have superb optical properties.
But, boy, do they splinter if you drop them! Nearly gouged out the front element on two lenses (Some of the dangers of having children! LOL!) Since then, I use nothing on the lens, but always keep the hood on (a £40 hood is cheaper than getting a lens repaired).

As far as the Cokin P system goes - I've used HiTech and Kood, as well as Cokin's own. As with all such filters, you have to watch out for scratching - so treat them like gold dust
In the long run, a square/rectangular filter system will last a lot longer... and once you've used ND grads (Neutral Density Graduated) for landscape work you'll never go back

Matt

Why don't you investigate the Cokin P system?
I have a Kood Circ Pol and a set of ND grads. That way you can just buy the P-adapter ring for each lens size

The P-system can just manage the SMC-DA 12-24 (if you modify a Cokin holder)... though I upgraded to the Lee & Z-Pro system (but can't justify £130 for the 105mm polariser :shock

HTH!
Matt

And I passed one up at £399... idiot
(Goes off to give self a good kicking )
Matt

Just to add to Don's suggestion...
You get much more control if you use Layers (There's some PSE tutorials on layers on my website)

* Add a new layer
* Fill with 50% gray (or grey if you're in the UK )
* Then use Filter/Noise/Add Noise
* Change the layer blend mode from "Normal" to "Overlay" (if Overlay is too much, change it to "Soft Light"

The advantage is you can adjust the intensity with the layer's opacity control; re-do the noise if needed etc etc.

You'll find there's plenty, plenty to learn in PSE!!

Have fun
Matt

Without a doubt: Robin Gillanders - "The Photographic Portrait"
Absolutely fascinating with some sublime portraits
Matt