Hey Gang,
Do you use filters? If you do what and when?

Thanks Tom

Tom,
The one filter I use often in my landscape photography is a circular polarizer. It is especially useful for water, leaves and telephoto work. It also reduces the effect of haze on canyon shots.
I do not like using a CPL for wide angle shots that include blue sky as it makes the blue too dark on one side. One can overcome that by using a filter for the land and then blending another exposure without CPL for the sky.
The camera bag has a few neutral density filters, but I rarely use them to reduce the shutter speed to blur clouds or moving water.
Some use a graduated neutral density filter to even the exposure between sky and land, but I do not like the top of the mountains and trees burned/darkened by the GND, and hence would rather blend two exposures.
A clear UV filter is not used.

Check your PMs.

I'd second on a polarizer as that effect can not be generated in post processing. Most other color manipulations can.

When I first set Cookie up I bought several filters thinking mostly about protecting lenses so skylights and I think amber and reds were ordered. Cookie spent a weekend out chasing deer and there was something just a bit short in every image. We finally tried some shots with and without filters on a distant sign board, and one could not read the smallest print with the filtered shots. Quite legible without the filters. Round filed the whole batch and now just keep lens hoods on for protection.

Cookie seasonally runs with a few pros (wildlife). They all have high end gear and not one of them uses a filter.

Given the science and coatings that go into fabricating today's lenses, slapping a piece of flat glass on the front end is probably not an optical plus.

The only other time a filter was called for was the eclipse run last year. Made our own out of some cardboard tubing and mylar. Low tech but was sufficient for seeing sunspots and shooting the fully exposed sun. No filter is needed for the diamond ring and totality phases. Could not justify high end glass for something that could be foiled by a cloudy day and might only come around every 8 or 10 years.

I have a clear filter of some sort but has no color. It is just for keeping dirt off of the lens . You have me thinking though 1 minute. I will try to see if the filter dulls the picture. Do you think a clear protector would do that?

ihookem:

My days of studying college physics and refraction are well behind me, so I'd suggest one simply do their own tests. Modern lenses are engineered with the knowledge that colors respond differently as they pass through glass, water, air, or whatever. One of the objectives of our modern lens coatings is an attempt to have those rays follow the same path or if not cause them to again converge at a common point.

Pick a distant target like a bill board or structure that carries several levels of detail all in a flat plain preferably perpendicular to ones position to eliminate depth of field issues. Sit up ones gear for optimum performance (tripod and remote shutter release) and shoot several images with and without the filter. One might also do a series with both auto and manual focus as well. Download and zoom into the detail with side by side comparisons at the same scale if possible.

Adding a layer to any lens will have an effect that may or may not be noticeable. Cookie is mostly dedicated to wildlife imagery and lots of her throw away stuff would be perfectly acceptable to a novice. Really nailing focus and exposure, however, produces images where one can count eyelashes or whiskers on the target. Todays high end optics are truly amazing and sadly expensive as well.

Please do post your findings whether they be positive, negative, or neutral. Given the downsizing and loss of resolution necessary for displaying images, I'd not bother with posting images unless one sees marked differences. I wish we had saved Cookie's examples, but we're hobbyist as opposed to publishing professionals and they were dumped at the same time the filters were round filed.

Have a good one.

For a UV filter, an expensive one should not noticeably degrade your image. Some cheap ones may. You could test your lens with and without a filter by photographing the want ads in the paper or a test pattern. You may see a color cast if your test target is white. Some will use a UV filter to protect the lens, but that is debatable for impact. I do not use a UV filter for impact protection, but always have the lens hood on, and also the cap when changing locations. I could see using one in a misty waterfall environment or blowing sand for example, or for fingerprints, as I'd rather wipe down a filter than the front lens element.

With any filter, there is the added chance of getting unwanted flare when shooting towards the sun or other light source.

I bought a very cheap ND filter at Best Buy when I was first starting and wanted a slower shutter speed for a creek. I found the filter gave a terrible color cast. Buy top of the line filters.

Some UV and CPL filter tests:
https://www.lenstip.com/113.1-article-UV_filters_test.html
https://www.lenstip.com/139.1-article-Polarizing_filters_test_2015.html

If you get a good UV/Protection filter it will not degrade the image and in most cases will help.
Since I started in the industry in 1975 I have seen many new lens sales because the photographer was told not to put a clear filter on the lens and something happened. I agree, don't by garbage (Cheap). Most reputable photo specialty stores, like us, only carry quality filters.
The effect filters depend on what you are shooting. Circ Pol, ND, etc

Yes, UV always, good quality. Circular polarizer for most outdoor/landscapes, and sunny days. Just buy good equipment.

It depends on the quality of an image that I get to capture, a filter is needed to enhance the features of the image.

I use a quality, multi-coated polarizer or protective filter.