I have a step up ring for my filters that makes me able to use either my lens hood or my filters, but not both. I tried taking pictures with a UV filter and Hood separately but I don't have a good enough eye to tell much of a difference. I know they both achieve similar effects to decrease haze and increase contrast, but if I have to pick one over the other, is there a clear better choice?
As you know, distant mountains are most often veiled by a bluish haze. This is a vapor cloud that often spoils the beauty of the vista. The same is seen when we fly; the clarity of our aerial image is tainted by the same phenomenon. What is happening is: The UV and violet light has the shortest wave lengths of the light spectrum. They can and do skip past some tiny particles of dust and water vapor. However they have a higher probability of colliding than the longer frequencies. When collisions occur, the UV light from the sun is scattered. Photographic films are super sensitive, and will record this scatter as a thick haze.
We can reduce the harmful effects of UV scatter by mounting a UV filter. Now the scatter is only seen if the light must travel many miles to reach our camera. In other words, the UV filter is worthless if the subject is a mile or less away. You should also know the popularity of the UV filter is mainly the product of camera shop salesman trying to line their pockets.
The digital camera also has sensitivity to UV light. Because the image sensor is delicate as well as precious, it is protected by a thin transparent cover glass. This allows the sensor to be cleaned when and if it accumulates dust etc. Now this cover glass is also a UV filter. That makes mounting a UV filter to the camera lens, a redundant act.
Let me add that the lens shade is used to shield the camera lens from stray light that originates from bright objects outside the field of view of the camera. If a lens hood is not used, there is a high likelihood that some of this stray light will intermingle with the image forming light rays. When this happens, optical flare is induced as well as ghost images. Flare robs contrast and ghost images are creepy. The lens hood is worth mounting, always.
Lens hood. It will protect your lens from flare while a UV filter will add some.
The only time you should use a UV or a Clear filter is when your lens is in danger from flying dangers such as sand or salt-water spray. Both of these can damage your lens, so if you are in a desert and the wind is picking sand, you can place a filter to sacrifice it instead of damaging your lens.
Should you be using a film camera, then the UV filter may reduce haze since film is UV sensitive but UV light does not reach a digital camera sensor since it is behind a filter already. If you were to need a UV filter for this, it would be beneficial to add the lens hood as well since a filter is a flat surface which can easily cause flare.