Protector filters

[jamesmartin]

I was wondering what peoples thoughts are on protective filters for lenses. I have a hoya hd protective on my zeiss, nothing on my canon 70-300mm but it doesn't get used as much.
Reason for getting it was I shoot a lot on the coast/inland etc so I thought it made sense as over time it would accumulate small scratches & if it got bad I could easily replace it with a new one. As I was cleaning it the other day it got me thinking, are they really necessary? Would small scratches ever show up in landscape shots if printed large? Or are they more intended for protection in case you drop it?
My zeiss lens hood is metal & I can hardly bend it so it already has pretty good protection. Apparently this hoya protector doesn't affect picture quality which was one of my initial main worries before getting one. If you had a really expensive lens like a otus would you get a good quality protector filter.....

[Boo53]

I use cpl filters for the polarising properties. Anything you put in front of the lens will reduce light transmission so you need to consider that as well as cost

[Tannin]

https://www.lensrentals.com/blog/2016/12/front-element-lens-protection-revisited/

Says it all really. Except that you still lose image quality every time you add glass. In particular, you lose contrast.

[Geoff79]

I’ve never actually heard of a protector filter. I just assumed that’s kind of what a UV filter was for. :)

[arthurking83]

I’ve never actually heard of a protector filter. I just assumed that’s kind of what a UV filter was for. :)

They're really the 'same thing' or so to speak.
As more and more folks become educated on what and how digital photography works, there's les and less need for manufacturers to push the UV filter marketing BS.
Digital imagery isn't affected by UV .. almost to the point that 0% UV is transmitted to your image. One of the filters in the filter stack on a digital sensor is a UV cut type(as well as an IR cut filter).

So to use a UV filter on a lens, which itself doesn't transit much UV light anyhow! ... is light using a torch in a well lit room to see better. i.e wasted effort.

OTOH, in some very specific situations a 'protective' filter can be of use .. like James says, he's on the coast, and worried about stuff on his lens.
In this situation, one could argue that a protective filter could be worth the effort, but not in that it will protect the lens wholly .. more so that you would have multiple protective filters and change them regularly to speed up your session.
That is, sometimes it takes some effort to clean a front lens element quickly and properly(each lens has it's specific quirks), so it could be a quicker and easier process to simply unscrew the now sea sprayed filter and replace it with another, and another, and just before you're ready to finish up, just use the bare lens(filterless) and finish up.

Move away from the spray a little(or just out of the weather) clean every thing up nicely and repeat above process.

But FWIW, the front element of most lenses(especially newer ones) is much hardier than 'protective' filters .. which also includes polarisers.
All my filters, the single ND I have, and all the polarisers, and the two UV/protective filters I also have, all have very slight scratching on them over the years of use(not abuse tho).
It's barely visible, and would only really be an issue when shooting into contra light(like Tannin said .. loss of contrast).
But, you don't really shoot a lens with a polariser into contra light(zero point using a polariser, in almost every instance of that situation) .. so my very lightly scratched filters aren't affected by those scratches in real world usage.
I don't use the UV protective filters, to be honest I can't even remember how I got them, but most likely came with a lens I got.

My most used lens is my Sigma 10-20mm. Pretty much my staple lens from the day I got it. I'd estimate that if I've shot say 1000 hours of photography outdoors, that lens would have done 999hrs of that.
Just about every environmental condition too, from sand storm to snow. a little sea spray, but not all that much. It has been cleaned reguarly, dropped regularly, bounced about on the rear seat of the car regularly .. dropped again reguarly, is now slightly out of alignment(internally), where one side of the rendered image is slightly blurrier than the other .. etc.
Front lens element is basically fine. has one small mark where it was dropped, more specifically I don't drop lenses, more so that I'd tip the camera off the tripod every now and then. I don't ever remember dropping on really hard surfaces tho, usually bushes, grass sand and such like, but stuff like salt bush can still be a very hard substance on something like a lens. lens does have very minimal 'scratching' marks on it if you look hard enough, but compared to any of my filters, looks like nothing considering the relative abuse they've respectively endured.

I'd estimate that a lens is roughly 10x to 100x harder to damage than your regular filter, no matter the filter type.

In fact a few years back I tried to deliberately see if an old lens would be easy to damage the front element too. Old Nikon 18-35 consumer grade lens. Used a kitchen sponge scourer to try to get obvious scratches on it .. zilch! .. I produced barely any more than it already had on it.
At this stage, the lens would have been about 15 years old and AF stopped working on it.

I've never tried any impact testing, and never saw any need too .. already enough of them about to show that lenses are much stronger than filters are.