Keith S Loc: Federal Way, Wa

From everything I have read lately the UV filters were used in the old days with film. Today's film is suppose to be much better with UV and may not be needed at all. I will be doing my own test on that since I dragged my old Pentax off the shelf a few weeks ago.
Ahh retirement, so much time to play around.
Keith

John_F Loc: Minneapolis, MN

Polarization is all about angles. As your lens is sampling the light by a differing angle from one side of the sky to the other, you should get a varying degree of polarization. Its all wrapped up in the physics of light.

Keith S Loc: Federal Way, Wa

John,
Thanks,
Ahh, physics. Isn't everything about physics? I finally understand that the polarizer should be used with a 90 deg angle to the sun for optimal performance. Less performance when the angle decreases.

rmalarz Loc: Tempe, Arizona

Keith, a circular polarizer would definitely be advisable. Careful when using one with a wide angle lens. Additionally, don't scrimp on the price. Once you attach a filter to your lens, it becomes part of your optical system. Purchase high quality, Shott glass filters. My personal preference is B+W filters.
--Bob

jerryc41 Loc: Catskill Mts of NY

Right, although you may not mind the effect.

https://havecamerawilltravel.com/photographer/polarizing-filter-wideangle-lens/

Here are lots of links about polarizers.

https://backcountrygallery.com/how-to-use-a-polarizing-filter/
https://www.lensrentals.com/blog/2017/09/my-not-nearly-complete-but-rather-entertaining-circular-polarizer-filter-article/
http://www.lenstip.com/139.25-article-Polarizing_filters_test_2015_Results_and_summary.html
http://www.techradar.com/how-to/photography-video-capture/cameras/best-circular-polarizer-filter-5-top-models-tested-and-rated-1320842
http://www.the-digital-picture.com/Reviews/Circular-Polarizer-Filters.aspx
http://www.lenstip.com/index.php?art=139
http://nikonrumors.com/2014/07/26/how-to-use-a-polarizing-filter.aspx/

http://www.lenstip.com/115.1-article-Polarizing_filters_test.html
http://www.lenstip.com/115.4-article-Polarizing_filters_test_Results_and_summary.html
http://www.techradar.com/how-to/photography-video-capture/cameras/best-circular-polarizer-filter-5-top-models-tested-and-rated-1320842\

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

The NiSi system allows you to use both. On that system the polarizer fits in the back and you can rotate it separate from the filters that fit in the front. I rotate mine until I get a really nice sky and then drop in my grad ND filter and shoot away. Works very nice.

camerapapi Loc: Miami, Fl.

I can only speak in my behalf and I tell you that many times a polarizer is not absolutely necessary, at least it is not when I am using my mirrorless cameras. I do recommend a polarizer if you want to darken the sky. A graduated ND filter darkens the sky when the intention is to cut down on the contrast of the scene to make it more pleasant to the eye.
Polarizers are very useful to cut or eliminate reflections from non-metallic surfaces.

waegwan Loc: Mae Won Li

catchlight.. Loc: Wisconsin USA- Halden Norway

Hi, I am a photojournalist from Norway...

Don't be afraid to crank up the white balance for certain lighting or seasons, but remember your taste or specific style may be different from my example.

Your image can be interesting and surreal right out of camera. Here is an example of an UN-edited sky from a few days ago. I used a polarize filter and cranked the K way up to 10,000.

My point is that, you can improve the sky and reduce the negative effects of a polarize filter by choosing white balance to tweak the blue along with a warm look.

(Download)

waegwan Loc: Mae Won Li

Thanks, I didn't know that. :-)

waegwan Loc: Mae Won Li

Nice, thanks for sharing. :-)

PhotoPhred Loc: Cheyney, Pa

Don't buy a cheap one.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

B&H are currently selling out grad VU ND filters that will soon be bought out by a tripod firm. They are selling some $230.00 filters for $28.00. But act fast. By the way, they fit my current NiSi filer system.
https://www.bhphotovideo.com/c/search?Ntt=100X150%20graduated%20filters&N=0&InitialSearch=yes&sts=ma&Top+Nav-Search=

amfoto1 Loc: San Jose, Calif. USA

Regarding Graduated Neutral Density filters (some earlier responses misread your question and were talking about standard Neutral Density filters, which are another matter)...

I assume you are shooting digital. If so, graduated ND filters are "old school", were needed with film but are not necessary with digital. You can do a much better job of it by making selective adjustments to the sky in post-processing software, than was ever possible with graduated ND filters. It's also possible with digital to make two images... one for the sky, the other for the rest of the scene. Then merge the "correct" portion from each in post-processing.

Still, some people insist on using graduated ND filters. If you do too, don't buy the round, screw-in type. You'll need the large, rectangular, oversize ones that fit into a filter holder that's attached to the lens. This is so you can adjust the transition line to match your composition, rather than having to make your composition always match the filter as is the case with the round ones. Also, be careful to get the glass, multi-coated graduated ND. Those are pretty expensive in the 100mm and larger sizes usually needed (depends upon the largest diameter lens you'll be using them upon), but they do a better job and are more durable than the plastic, uncoated ones. Typically you would need 1-stop, 2-stop and maybe 3-stop Grad ND. There also are "soft" and "hard" transition types. If using with a wide angle lens, usually a "soft" transition filter is needed. Usually the "harder" transition type are used with longer, telephoto focal lengths, but it depends upon the scene and sometimes a sharper "hard" transition is needed with wider lenses too. But even with the higher quality expensive filters, you could instead do a better job in post-processing with selective adjustments.

I still have my Graduated ND filters from when I shot film. Haven't used them in years, since I now shoot almost exclusively digital and they are unnecessary and a pain to carry around, slow and cumbersome to use. I only keep them in case I need/want to shoot with film sometime.

You might find standard ND filters helpful. Gray all over, they are used to allow you to use slower shutter speeds and/or larger apertures than would normally be possible with your digital camera's lowest selectable ISO. Although somewhat specialized, standard ND filters may be the only way you can get blur effects or shallow depth of field effects in brighter lighting conditions. If those are things you need to do with your photogrpahy, get one or two fairly strong, high quality, round screw-in ND filters... say a 4-stop and a 6-stop, which can be combined (stacked) for 10 stops if needed.

There are also Variable ND filters, used the same way as standard ND and for similar purposes. While convenient, those have their problems. First, they're expensive. Some of the better ones are extremely expensive. The less expensive ones are notorious for problems with uneven effect and ugly color tints. Even the higher quality, very expensive ones aren't completely free of those problems. For still photography, Variable ND aren't generally needed. They may be more useful for video, but a number different fixed strength ND would be better.

Regarding a Circular Polarizing filter...

A Circular Polarizer can deepen a blue sky. And, unlike most other filters, it can do things that are difficult or impossible to replicate in post-processing. I'd highly recommend getting a good one in the size you need for your favorite landscape lens first, then plan on getting other sizes if needed for other lenses. CPL also can be used to control reflections, enrich colors, and are one of the most generally useful filters for digital photography. Highly recommended. (Personally I use CPL most for scenic shots with shorter focal lengths, far less often with telephotos.)

A very good value are B+W XS-Pro and F-Pro Kaesemann CPL. They are among the highest quality, but cost half what some others of similar quality do. The difference between them is that the XS-Pro have 16-layer "Nano" multi-coatings and are mounted in "slim" frames. The coatings make the XS-Pro easier to clean and a bit more resistant to oils, water, dust, scratches. However, slim filters can be a little more difficult to install and remove... especially in larger diameters. The F-Pro are also very good to, with 8-layer multi-coatings... and their "standard" size frame is slimmer than some other brands use. Both use high quality Schott glass and are mounted in brass frames that are less likely to get stuck than aluminum used on many other filters. They also are both now "High Transmissive" CPL, which aren't as dark as standard CPL, so don't "cost" as much light lost to the filter. One of the problems with CPL and a reason to not use them at times is that in conditions when you are struggling for enough light, a CPL reduces it by a little more than 2 stops, depending upon the filter's setting. The HT or High Transmissive type allow a little more light to pass... at max setting they reduce it by about 1.5 stops. It doesn't sound like much, but can be the difference between getting the shot or not when light conditions are low.

B+W also make standard ND filters that are very good quality, though not as great a value as their CPL, compared to other brands.

B+W doesn't make the rectangular Grad ND, such as are recommended above. They only make the round screw-in type.

Also, especially when used on wide angle lenses a CPL can give uneven effects that can be seen in broad swaths of blue sky. This is because the filter's effectiveness depends upon where the light source (i.e., the Sun) is located. CPL have strongest effect with light source at 90 degrees, tapering off to no effect at 0 or 180 degrees. For example, when the sun is directly overhead, the filter will have strong effect... but if it's low on the horizon directly behind you or you are shooting a sunrise or sunset with it directly in front of you, the filter has no effect. (Actually, it's usually recommended to use no filter when directly shooting sunrises and sunsets, because any filter is likely to cause flare problems.... a CPL is among the worst for this because it's made up of multiple layers of glass).

The wider a lens' angle of view, the more likely there will be times when the effect of a CPL on it will be uneven. When it occurs, the uneven effect can usually be seen in the camera's viewfinder. It may be "hidden" in cloud detail or similar. And it isn't necessarily a bad thing, can even be useful at times.

alfeng Loc: Out where the West commences ...

Excellent tip ...

... Excellent photo.