Our fellow forum member Harvey Melvin Richards recently posted some woeful images of his wonderful 40-150mm 2.8 Pro lens with 2 large scary scratches in the front element. So sorry man, I cannot stand my lenses having scratches on them. Especially expensive ones. But instead of hijacking his thread, as I think he has plenty of responses to ascertain his situation (124 to be exact) I thought I would try one last time to end the debate and talk about what is fact and and what is fiction when it comes to this filter debate. In the end its always a personal choice, but at least for newbies and veterans alike, the decision should be based on actual real information rather then opinion and hyperbole. I used to never use just plain UV filters as I rarely owned cheap lenses and bought into the story of nothing gained and much to lose argument. This was until I scratched my Canon 24-70 f2.8 L. That evening the only thing I could narrow it down to was when I took it out of my bag the lens cap had fallen off and during a long hike back to the car It marked the lens with a 1/8" scratch on the front element. My thought was how can plastic (seemingly softer then glass) scratch the front element, but regardless the deed was done. My scratch and Harvey's scratch have something in common. Both could have been avoided with a filter. Now the debate begins. Well I went on a hunt for info back then and the same stories were about. "UV filters are a waste of money". "They reduce sharpness and resolution" "they add unwanted flare to your photos" "They are a marketing stunt aimed at making easy money" Every time I read a diatribe on someone being against UV filters they never seemed to post ANY SAMPLES! Took awhile to find anyone with a real test but in the end I did find some real world tests that changed my mind. That was awhile ago so I did another search today. Same thing as a few years back. Plenty of blogs going on and on about how bad it is to use UV filters. All without a single image to prove it. Well then I found one that actually did do a real test. He wrote it very subjectively without making anyone feel stupid. Do Filters Affect the Resolution of Lenses? He shows there is no adverse effect AT ALL when using high quality filters. Image sharpness is NOT effected. Flaring is NOT effected and does not add any additional flare attributes the lens didn't already have to begin with. He DOES note however that sure, in certain situations you can get ghosting or some adverse effects from light sources, but then makes a good point. Take the filter OFF in those situations. So which situations does a UV filter ruin photos? Here is a nice post on DP Review about it: should-you-use-a-uv-filter-on-your-lens It seems ghosting can appear in photos that involve small concentrated light sources. Things like city or street lights, candles in dark rooms, etc. For me these types of photos make up less then 1% of my photos. Maybe others are more like 10%. Regardless, once you know what not to do with a filter on, isn't it easy enough to remove it? Then you know that 90% of the time your lens has got that extra bit of protection? Ok no, it will not help if a baseball hits your lens. But then again nothing would guard against that. A lens hood might. And even one of our forum members (thanks eteless) stacked 7 filters together in Harvey's post and showed it did almost nothing to image quality. At least nothing I could see as a deal breaker. Also notice a common theme among the tests. No one is using cheap filters. Here is another example from photography life showing cheap filter results compared to high quality filter results: https://photographylife.com/lens-filters. So, so far we have the following facts to chew on 1. High Quality Filters do not effect resolution or sharpness of the lens. 2. Flare is also not effected nor do UV filters create additional flare where the original lens had none. 3. Stacking multiple filters do not degrade the image noticeable to the naked eye. 4. Low quality or cheap filters DO IN FACT degrade image quality 5. UV filters can induce ghosting of small, bright, concentrated sources of lights. Worsened by smaller apertures. Its recommended to remove the filter in these situations. Ok now for some counter arguments. However, these arguments are not against using filters. Im going to argue how much abuse a front element can take before actual reduction in quality begins to happen. Thanks to Vinepocetine he posted some very good examples of people absolutely bashing their front elements and seeing what happens. The results will probably shock you. Hope you are sitting down. Here is his post https://www.mu-43.com/showthread.php?t=72997&page=2&p=734730#post734730 Ok don't want to read all the links? Ill summarize. It does very little. Even a completely smashed element does little, especially at F4 or below. However once pointed into bright lights or stopped down past f7.1 or so, you will start to see some issues. On a very old lens once I used a black marker as suggested in some forum once. I could see the black marks at f11. So we add a fact. 6. Front lens elements can take quite a bit of abuse before showing adverse effects in image quality. Especially at F4 or below. Ok Ive written a whole lot here :horse: but without spending too much MORE time on this, another lesson to take away is dust and dirt are probably the most common contributors to image degradation of your images and is discussed a bit in some of the links above. Everyone knows that you should keep your front (and rear) elements as clean as possible. Microfiber and lens cleaners are easy enough to find. Lens pens are really nice as well. Always use a bulb blower to clean of any physical dirt on top of the lens before wiping. Ive also heard that finger/skin oils can harm your coating if left unchecked for long periods of time. Now I have kids. My friends have kids. I photograph kids all the time. Its next to impossible to keep my lens clean as the younger ones find it hilarious to scrunch their nose up to my camera. "Yea, thanks son. We'll talk about this 10 years from now" hehe. Anyway the more you clean the front element of your lens the more chances you have to getting a scratch. A microscopic piece of sand being the worst offender. Im happy to clean the front element of my lens once every 6 months or so. The filter gets a wipe down every few days or after a particular 'dirty' day of shooting. So for those you who do not 'believe' in using filters have a point and some justification to your choice. If you simply are more comfortable with a naked lens AND you could care less about scratches, dirt, cleaning the element, or shipping your lens off for a repair, then you can be happy about your decision. Just remember its a choice/opinion and that there is no evidence that filters cause more image problems then they solve. The biggest points I can agree with not using a filter would be 1. A hard blow directly to the front element can possibly smash a filter before a front element might shatter causing scratches from the broken filter to the front element (though I can't find any actual factual evidence to support this). I think this would have to be a fairly strong direct hit and most likely can be solved using a lens hood. Though Lens Hoods also provide great protection regardless of using a filter or not. 2. An indirect blow that would bend the metal frame around the filter threads could potentially cause you a lot of problems in trying to remove the filter from the lens. This would bum me out too but again, a lens hood could protect against this, and I bet after some sweat (and tears) you could manage a way to get it off. 3. If you own a large collection of lenses, filters can end up costing more then the rare time you would have to repair a lens. Its a valid point. However to me, I would rather spend the money upfront then worry about shipping a lens off with the possibility of losing the lens in the mail or having to come up with a few hundred dollars at once. So for those of you who absolutely HATE the idea of having a scratch on your front elements (me), or trade and sell your equipment often (me again) or shoot in environments that subject your lenses to danger (me and me again), or really do not like the idea of having to repair a lens for something that could have been avoided then rest assured, using a high quality, multi-coated filter is perfectly fine and may even help you sleep better at night. Just remember those situations where a UV filter can cause adverse effects and be sure to remove it (and then replace it again) at the end of those sessions. So, everyone satisfied? Probably not. Feel free to agree or bash away. Im cool with it.