Noooooooooooo ---  no need for such drastic action as telling the wife you got it wrong !!!

The scene above didn't use the benefits of the filter to the best advantage, it doesn't mean there are not loads of shots where it will perform so much better.  

Firstly in the shot above you are fighting a very difficult battle because because you are working against the light rather than with it.  Now imagine if you had lowered that tripod down to its unextended height and set up on the grass next to the stream in front of you. The shot from there would have been a more abstract nature of the water and rocks, zoom halfway to 15mm to get rid of the vignette and the filter would have given you a lovely shot of water movement over the rocks and down the fall.  The warming effect of the filter would enhance the image, you don't have any sky or clouds to go funny colours, but a nice warm tone cast onto the rocks and water. No tripod shadow either, if you use that lens on an extended tripod it will always capture any shadow that is there.
Imagine the lovely quality the filter would give to a sunset by the sea. The warm tones would be working with the light and the light reduction from it will give a super effect to the waves motion.
The filter has many uses but it may mean using it on shots where its benefits come into play and don't work against the light that is already there. 

Getting the best from filters and very wide angle lenses takes a bit of practise and techniques that are unique.  Anyone who has tried has made all the mistakes and more. I am no expert the only knowledge I have is from practise and talking with professionals who specialise in this type of photography.  That lens works best when up really close to the foreground, hence the low tripod. It has a very close focusing range and I tend to think of it as almost taking a macro shot of the foreground with the rest of the field of view contributing to the overall effect of the image. I try to use F11, or as near as possible, because that is where you will get the sharpest image with a C size sensor and at that aperture with focus on the middle ground everything will be in focus from a few inches to infinity. I like to use filters to balance out light where needed or to alter shutter times as you have here.

Well I hope that is helpful, as it is intended to be, and doesn't put you off experimenting with wide angles and filters. It is a very interesting genre of photography and one which I love if only I had the time to use it.

Richard.

 

 

And every one said, 'If we only live,
We too will go to sea in a Sieve,---
To the hills of the Chankly Bore!'
Far and few, far and few, Are the lands where the Jumblies live;
Their heads are green, and their hands are blue, And they went to sea in a Sieve.

Edward Lear
http://www.nonsenselit.org/Lear/ns/jumblies.html