Hard to spot the difference!

After my recent purchase's of a Sigma 10-20mm and a Hoya Pro-1 circular polarizer I went on a weekend out shooting pics in the desert.

What I struggled to see was the difference the polarizer made to any off my shots.

What should I be looking for in the in the pictures taken and what ideally is the polarizer meant to do??

I am sure it is a matter of understanding what I am doing and practicing it, but just not 100% sure.

I also think I will look at buying a 17-40L as many of you recommend as the 10-20 is sometimes just too wide.

The easiest way to see the effect of the polarizer is to point your camera to the sky (preferably with your ear pointing at the sun) and rotate the filter. You will see the sky change from light to dark blue (and if you have any clouds you will notice the contrast change).

Also, anything wet with a lot of glare (like the ocean, lakes, or even wet grass and leaves) will change the amount of glare as you rotate the filter. This is one of the most significant uses of the polarizer to me as it can signficantly reduce the glare from such surfaces (oh, and glass too). Try looking through a window and, again, rotate the filter.

Like Poco said, you need to rotate the filter while looking through it to set the position for the desired result. That's why the filter can rotate in the mount (the ring with the threads on it).

The most common things that the polarizer can change are the intensity of the blue in the sky and "cutting through" reflections.

The reflection thing is the most common reason that I use a polarizing filter. For example, if you want to photograph fish swimming near the surface of the water they are in, the polarizing filter can reduce or even virtually eliminate the reflections on the surface and let the fish be seen clearly. Same goes for shooting a storefront display. The reflections on the near side of the glass can be reduced using a polarizing filter, making it possible to take a much better shot of what's behind the glass.

Don't expect to reduce reflections on metallic surfaces, though. That usually won't happen.

Again, as Poco said, make sure that you rotate the filter to see and control the effect before taking the shot.

That explains why it doesnt work. Rotate the end and you can see the reflections go up and down in strength.

I rotated the polarizer, but the only noticeale difference I saw was that you would get either a constant lighter blue or you get a darker blue in a strip and then it would lighten off on the sides. I guess the idea is to make the sky a constant blue. However I did feel it made much of a difference to not using it. I guess I will have to try it again and pay close attention to with and without!

Would using on a wide angle make any differance as there is a lot more sky to contrast??

I will have to try it also looking at water reflections and see what it does for myself.

Thanks

The problem with the sky darkening is that you are using a very wide-angle lens. The effect with the sky changes with the angle to the sun. With a very wide-angle lens, you are seeing the changes because you see all the angles.

That's a known - a polarizer has maximum effect on the sky when aimed at 90 deg. to the incoming sunlight. With wide angle lenses, you accept so much more sky that you'll see the gradation as you move away from it. Typically, a polarizer's less recommended for sky effects on lenses under 28 mm (FF), which translates to 17-18 on an APS-C. YOur 10-20's almost totally in the "too wide" zone. I'd consider, for this situation, a rectangular graduated neutral density filter. They fit into slotted mounts so you can adjust where the transition occurs and the mounts can be rotated. They're available in your choice of densities and hard or soft transitions, and will hold back the sky so it's less "overexposed".