I'm usually very good at getting water/finger marks on lens, so I must use something for protection. Is there any downside of using an UV filter instead of a protector filter?
Example: Hoya HD Protector or Hoya HD UV?
First, I wouldn't be especially worried about the odd fingerprint, dust mark, or water on the lens as it would take quite a bit to make an impact. To give you a sense, helpfully posted in another thread is this lens which, despite massive damage to front element, still works and does so reasonably well.
Second, there are ways to reduce your incidental contact with the lens such as using the lens hood and ensuring you cap it when its not in use. If you do get something on it, despite that, then cleaning tools such as the lens pen and microfibre cloths will help you remove it. That's if you even notice!
However, if you do get something like a UV filter, which will help with this problem, bear in mind that you still have to clean that with reasonable care or you introduce potential image artifacts beyond what the filter will already do. By the way, the downside really applies to both options in a way, primarily artifacts from light sources appearing in unexpected places. It is, after all, another piece of glass added to your lens.
The only advantage of an additional protection element (UV or protector) is that it is cheaper to replace should you scratch it when you rub it with your t-shirt/accidentally drag dirt over it. And for that purpose they do admirably. Having said that small specks of dust and dirt rarely have a significant impact although water drops can.
But if you're going to add another layer of glass then it's probably best to make sure it’s as good a quality piece as you can get, commensurate with the quality of the lenses it goes onto.
So the best quality one for the price will be the better option.
I tend to have a polariser strapped to the front of my lens whenever shooting outside (which is, of course, the third option).
Given that digital cameras are less sensitive to UV light than film is, then the choice is moot.
Personally, I'd tend to opt for the UV filter option, when I'm not using a polariser; as I'd still be able to use it with my film cameras.
It's an ongoing debate in the photography world and blogosphere whether having a UV filter is a good or a bad thing (whether it reduces the quality if images). Assuming you want one, do like spg said and get a good quality filter. Putting cheap plastic in front of (quality) lens elements doesn't make much sense as it essentially can reduce the image quality of the lens, causing lens flare etc.
I personally tend to use a UV filter or a lens hood to protect the lenses. I've got a Hoya Pro 1 Digital series UV filter and some B+W filter and I haven't had any issues with either one.
Also notice that if you've got a wide-angle lens, you may need a slim-line filter to avoid vignetting.
It just occurred to me that anyone of us could make a simple cover for the lens using a plastic bottle of the right diameter.
I've been spending 'hours' looking for the right protection. My new cameras now has a step up (adapter) so to avoid vignetting.
I think I'll get a plastic bottle. Cut the top off and slip it over the lens. Add a piece of parachute cord that was $5 for 100' at Amazon and I've got a no lose free protector. If the bottle's a bit too tight a slit along its length of the right length or 'angle' (maybe slice it like a circular ham slice) Anyway that would allow it to spread if you're off by 0.1"
I was so 'groomed' to buy something instead of doing what I would have done when I was 8 years old...
No. The filter stack directly in front of your camera's sensor already has a UV filter.
Whether either an UV or a protective filter actually provides a protective benefit is a hotly debated topic. Because a thin flat filter is more likely to shatter than a thicker and differently shaped front element made of different materials, there are cases where a shattered filter may actually increase the amount of damage to a lens' front element by causing multiple scratches. One must also consider the optical penalty imposed by adding two more air/glass interfaces into the optical path. Just how detrimental that will be depends on the specific shooting conditions as well as the overall quality of the specific filter and its coatings.
For more about the overall subject of To filter or not to filter (for lens 'protection'), that is the question, please see the following questions here at Photography at Stack Exchange:
is it normal to get significant lens flare with a 50mm f/1.8 prime lens?
Will a filter cause more or less damage when lens is dropped?
How do I remove a broken/warped UV filter from my lens?
Do cheap filters have an effect on image quality?
Front element shattered, can I have my lens repaired?
What kind of filter (if any) should I use when photographing a theater scene?
Does high reflectiveness of digital sensor lead to poor lens performance?
How durable are external lens coatings?
Can incense damage a lens?
What could cause this visible artifact which seems to a be a glowing inverse of something outside of the frame overlayed on this photograph?
Are there any downsides to using a good-quality UV filter?
What is the downside of a cheap UV filter that is used solely for the protection of the lens?
Does the quality of a UV filter make a difference when used with a cheap lens?
What effect does a UV filter provide?
Should I put UV filter to protect the lens even if I put a lens hood?
"Filters must be destroyed!" (Must every UV/protection filter question get this response?)
Beyond our site here, there is a good series of blog articles by Roger Cicala, founder and chief lens guru at lensrentals.com, that addresses the issues surrounding using filters for protection. They are presented below in chronological order.
The myth of UV filters
The Glass in Front of Your Glass: All About Filters
Good Times with Bad Filters
Front Element Lens Protection Revisited
Yet Another Post About My Issues With UV Filters
My Not Quite Complete Protective Filter Article
Generally, digital sensors are far, far less sensitive to UV light than film, because of this you probably wont notice much, if any, difference between using a UV or clear protector. Personally I prefer to use a clear protector, 1 - because I don't use film any more so don't feel I need to keep one around and 2 - even though I know the UV filtering probably makes no difference, it's nice to know my lens has an uninterrupted view of the world.
Whichever one you choose make sure you get the highest possible quality filter you can afford. I use the Hoya HDs but if your budget is a little tighter the Hoya Digital filters are also very good. Don't even think about the cheap eBay filters - I had some and they ruined every shot I took, I was surprised quite how bad they were.
Some digital cameras have a built-in UV filter, so using UV on them is the same as using a protector.