What filter do you use for concert, low light photography? I'm buying a Nikon F mount 24-70 and not sure what type of filter? Clear, UV?
I've never used a protective filter on any of my lenses. If you are not careless and use basic common sense, there is very little chance of damaging a lens in normal use. Volcanic eruptions, sandstorms and warzones may be exceptions.
The downside(s) of a 'protective' filter is that it's an extra piece of glass in the way of your image. Even if it's a high end filter it will still affect image quality to a greater or lesser extent.
If you feel that you absolutely must have a filter for your lens, a multicoated clear filter will be your best bet.
Though it's taken outside of a theater instead of inside, here's a perfect example of why you don't want any flat surfaces on the front of your lens when shooting in a dark environment with a few bright spots in the scene.
The bright lights on the upper left are reflected reversed and upside down on the lower right.
The best solution when shooting in such an environment is to use no filter at all. Instead, use a lens hood to block stray off axis light from causing flare and to also provide physical protection for the front of your lens.
Whether a UV or other 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 denser 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. When shooting a scene that is mostly dark with a few bright areas and highlights, even multiple coatings aren't perfect at preventing reflections that cause this type of flare known as ghosting.
My own personal experience:
I don't use "protective" filters except in rare circumstances when there's going to be sand, salt water spray, microscopic pieces of hot metal (think machine shop), etc. flying around in the environment in which I am shooting. The vast majority of the time, there's no filter on the front of any of my lenses. Though I do have a couple of clear filters in my bag just in case I need them, I can't even remember the last time any filter other than a circular polarizer, which I occasionally use for the optical effect, has been on any of my lenses.
I DO use lens hoods religiously when any lens other than a 17-40mm (for which the wide and shallow hood doesn't provide much protection from either stray light or physical hazards due to the lens' wide angle of view) is mounted on one of my cameras. I also use lens caps, both front and rear, when lenses are stored in my bag. When I'm not shooting with the camera to which it is mounted for any extended period of time the front lens cap is placed on the lens, especially if I'm in a crowd or other hazardous environment.
I've got lenses I've owned 10-15 years while shooting sports (mostly American football from the sidelines) in all kinds of weather, sports and pep rallies in crowded gymnasiums, music acts all the way from bar bands in crowded, rowdy bars to commercially staged outdoor festivals, the rare wedding, parades, other community events, etc. My 70-200/2.8 (2010), 24-70/2.8 (2012), 17-40/4 (2013), 135/2 (2017), 100/2 (2016?), 85/1.8 (2015?), 50/1.4 (2011), and 35/2 (2020) don't have a single visible front element scratch between them.
Several lenses have been dropped or taken hits while attached to cameras. One lens had to be sent to a service facility to have the internal optical alignment adjusted after a particularly nasty fall while attached to a monopod. But in every case the hood protected the front element from even the slightest damage. Some of the hoods do have multiple scratches, cracks held together with super glue and/or tastefully black duct tape, and even a paint rub or two. After being glued together several times until it would no longer stay glued, I had to replace one hood at well less than the cost of a decent UV filter. The front lens elements of all of these lenses are still immaculate.
My 24-105/4 bought in 2011 has had a single speck smaller than a tiny grain of sand missing from the front surface for around ten years. A young person stumbled towards me and managed to get the metal handle of a wire brush inside the lens hood when I was shooting a fundraising car wash. It's not detectable in a single one of the well over 100K photos I've since taken using that lens.
In my opinion the worry about front element scratches is vastly overrated, particularly if one conscientiously uses lens hoods that provide better protection while also providing a potential optical benefit compared to a filter that probably doesn't provide near as much protection as many people think it does while also contributing an optical penalty. If your lens takes a hit hard enough to break a filter, you've got more to worry about than whether the front element has a minor scratch. The internal optics can be knocked out of alignment, the lens barrel or internal zoom/focusing helicoids can be bent, or even the squareness of the lens' or camera's mating flanges can be tweaked.
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?
Is a UV Filter required/recommended for lens protection?
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
There is no physically plausible way in which putting something in front of your lens will either make your image sharper, or make more light hit the sensor.
Filters are useful in other situations than the one you describe. ND filters are useful when you have way too much light for the shutter speed you want to use (e.g. photographing waterfalls in bright sunlight). Polarizers are useful when you have reflections you want to get rid of (e.g. photographing a body of water), or when you want to make colors (especially in bright sunlight) more intense.
UV filters, as others have said, offer no real benefit on modern cameras. Here is a blog post demonstrating their effect on image quality in extreme cases.
Either filter will work fine, and having the UV component would be beneficial when you're shooting in normal light (i.e. a non-concert setting). CORRECTION: though the UV filter won't harm anything, it won't offer any benefit. Most digital cameras filter UV light in/near the sensor itself. Go with a clear filter instead.
As long as you don't buy something really cheap, you shouldn't have any degradation of your image. Just make sure to thoroughly clean the lens itself and the back side of the filter before you screw them together (use a lens cleaning cloth, not an old t-shirt). Then keep the front of your filter clean at all times. A dirty filter will affect your image, especially in a concert lighting situation.
I'm amazed that people would recommend going even a minute without a filter. In a concert setting, you could have people dancing, jostling, spilling drinks, bumping your lens... Not spending $$ on a filter to protect a $$$$ lens seems crazy to me.
Using a physical filter is probably a bad idea but, having said that, a circular polarising filter will introduce a gain grain on your images and possibly artifacts which may be undesirable. If shooting in RAW you can always post process darker image exposures to monochrome and overlay the colour image for an interesting effect.
A lense hood may be advisable if there are likely to be bright sources not directly in the frame but still hit the lense at an angle. Lasers are one such interference common to concerts