Funny no one ever suggests genuine Canon, Sony or Nikon lens protective filters... or for that matter find a specifically designed protective filter from the manufacturer as an accessory in the box. Isn't it odd that they are all aftermarket products...Kind of like paint protection for your car, or special covers to protect your trucks mud flaps.

As an ending note, years ago I destroyed a Canon 24-70 f2.8 when the shattered shards of a broken filter scratched the lens coating beyond repair. I thought I was being wise. Since then, never a problem going bare lens...

It probably doesn't matter, but under certain conditions they do have negative effects. Used car salesmen and UV filter salesmen I think come from the same family DNA. Arguments will be endless.

Unfortunately, this question, operating to protective filters, usually opens up a can of worms and as you can see the "shouting and counter- shouting has l already started.

The anti-filter came to insist that protective filters will introduce flare and negatively affect sharpness. The pro-filter folks remind us of the possibility of serious lens damage due to various impacts, dust, dirt, great fingermarks, etc.

Technically speaking, anything you place in front of you, even the finest optical glass coated filter can possibly cause the aforementioned issues. A poorly crafted filter will certainly do so. I high-quality filter such as the kind made by B+W, Zeiss, and other reputable and time-honoured manufacturers will usually NOT cause any perceptible loss of image quality.

As for wide-angle lenses, B+W has a very comprehensive stock of THIN filters for wide-range lens applications. Also, note that with ultra-wide-angle lenses LENS SHADE usage can be problematic. The shade would have to be very large and shallow to preclude vignetting, the same problem caused by a filter in a thicker rim or made of thicker glass.

So, here is my personal experience. I do quite a bit of industrial photography on construction sites and other hazardous environments. I am dealing with airborne particles, metal filings, sparks for welding, sawdust, etc. I will use the protective filter in those situations. Over the years, 5 filters needed to be replaced because of damage that would have seriously harmed the front element of my lenses. I have made extremely large prints for trade-show booth displays with no loss of quality due to filter usage. You have used the filter on your other lenses, so I assume you are satisfied withte the quality.

A serious head-on impact or dropping a lens on a hard surface will cause serious damage regardless of filter protection. If the filter is shattered, the shards of glass will, in turn, damage the lens. A lens shade may prevent scratch of the lens by heavy brush or sharp twigs in the woods, etc., but again would not abate a head-on impact.

Here is a link to a very comprehensive website. It explains the thin-filter usage and has a handy "vignetting" avoidance tool that will hel you determthe correct filter for your focal length and filter mount diameter.

https://www.the-digital-picture.com/Reviews/UV-and-Clear-Lens-Protection-Filters.aspx

I hope this helps.

Here is a link to a very comprehensive article pertaining to a light transmission of "protection" filters.

It includes the mysterious .03% thing and also includes other optical phimonina.

This has nothing whatsoever to do with the issue of possible vignetting or pros or cons as to the use of thin or standard thickness of filters. It has nothing to do with lens caps!

If there's any visually perceivable issue of loss of lig transmission or optical distortion caused by a filter, it will be present over the entire filter, not just the edges. If the is any vignetting it will be caused by the rim, ending or the adapter ring, retaining ring, or filter hold interfering with the lig path even before it passes through the front element. That could be due to the thickness of the filter or not. It depends on the diameter of the filter being too mass for the lens or the filer being too f far from the front elemental. As the les is stopped down, the rim, edge or other aforementioned obstruction comes more into focus and the degree of vignetting worsins.

If you have the appropriate filters and lens shade for your wide-angle lenses, vignetting should not occur.

At my studio, I do not have the optical analyzing instrumentation to test filters transmission. I have to go by manufacturers' specifications or independents tests. In any event, I have used skylight, UV, and clear protection filters where required, made very large prints, in some cases photomurals, from the negatives and digital filer, over many years, and never observed a loss of IQ.

If any of y'all can SEE a transmission loss of .03%, indeed you have a rare talent!