Filter comparison "none" " UV" " 81A" and "polarize" .

[dvdowns]

I am doing a set of tests on these filters but not seeing huge differences , maybe I won't , possibly the wrong subject . Maybe someone can suggest one[?] subject that will show the major differences in these filters .

[Rokcet Scientist]

Originally Posted by dvdowns

[...]Maybe someone can suggest one[?] subject that will show the major differences in these filters .

I doubt it.
And, anyway, reading up on those filters is a whole lot quicker and clearer.

[ohenry]

I can understand why one might compare a UV to a 81A filter, but a polarizer has a totally different use.

[dvdowns]

I realize they are very different , [ I noticed that the UV has a mild "81A' effect] , which is why I was wondering if one subject used for comparison would help to show where a polarize filter is good , as well as show the strengths of the 81A . So far I like the 81A filter's effect... sort of like afternoon sunlight .
I have read up on these filters but I understand fully what they are saying then in half an hour I have forgotten what I have read . Posting a question also has the advantage of geting to the crux of whichever part of an article I don't fully understand . And when you have a memory like mine you will understand that there is no substitute for going out and doing some tests so that I will be able to explain to someone else what difference they make , helping me to remember better .

[dmacgee]

81A and UV have very similiar effects. I think the main difference is personal preference. I have on or the other on all of my lenses more a protection for the front element of the lens that for the filter effect. Although they do cut the haze effect somewhat.

The polarizer is definelty a different animal as mentioned. It will saturated colours and cut refelections, ideally your subject ant its light source should be a 90 degrees to each other. A polarizer also adds a couple of stops, the UV and 81A won't affect the stop.

Dave

[dvdowns]

Since posting this topic I have learned a bit more . I was using the wrong test subject here and never used the polarizer properly . 81A indeed makes pictures much warmer in normal daylight shooting . The polarize is another story though , because it is a circular polarizer I assumed this meant it was the same effect all the way around and never needed to be rotated . Rotating it has a huge effect on some pictures .. an oil patch would normally have a bright glare reflecting off it , the polarizer turns it into a black patch . A car has light reflecting off the top and sides , rotating the polarizer can either remove reflections from the side or top but not from both because the light is 90 degrees different in reflecting off those surfaces . Why the heck does a circular polarizer need to be rotated ? how is it made ?

[Rense]

Take a look at this pdf file filters can make all the difference from TLR

[richardpcrowe]

Tiffen: Polarizing Filter Effects
https://post.craigslist.org/manage/723818383/qyp95

Replacement Light Bulbs.com: Filters
http://www.replacementlightbulbs.com/tipsfilters.html#Filters

PSA Journal – Using CPL in combination with a linear polarizing filter
http://findarticles.com/p/articles/mi_m1306/is_1_73/ai_n17154395

Filter Connection – Facts on Filters
http://www.2filter.com/faq/faq.html

DPFWIW – Filter Options for Digital Cameras
http://www.dpfwiw.com/filters.htm#why

Schneider B&W Filters
http://www.schneideroptics.com/filters/bw.htm

Hoya Filters
http://www.thkphoto.com/products/hoya/index.html

Photofilter.com – Filter Information
http://www.photofilter.com/infomap.htm

Digital SLR Photography Tips - Using Photographic Filters
http://www.all-things-photography.com/photographic-filters.html

Photo Secrets Tips – Andrew Hudson
http://www.photosecrets.com/tips.filters.html

Popular Photography – Filters Vs. Photoshop
http://www.photosecrets.com/tips.filters.html

Chroma Software – Photoshop Photographic Filters Plug-in
http://www.chromasoftware.com/photographic_filters.htm

[w7apd]

Originally Posted by dvdowns

Why the heck does a circular polarizer need to be rotated ? how is it made ?

You have to rotate the CP because it's still a linear polarizer at heart, and the polarizing effect depends on how it's oriented.

A circular polarizer has 2 layers. The first layer is the polarizer material and is exactly the same material as in a linear polarizer. The magic comes in the second layer, called a quarter wave plate, which takes the output of the linear polarizer layer and applies a twist to the wavefront so the light reaching the film (ahem, or sensor) is circularly polarized.

Most autofocus sensors, and some lightmeters, use prisms to sample the light which themselves act as polarizers. If you use a linear polarizer with such cameras, it's possible to have the LP "crossed" with respect to the polarization of the AF or meter -- with the result that the camera's electronics may see the light correctly or not at all. Adding the quarter wave plate ensures that the camera's bits will always see the same amount of light regardless of the orientation of the polarizer.

Circular polarizers give exactly the same results as do linear polarizers, and a CP can be used with any camera.