CWW Loc: North Jersey

Greetings, Looking for some information regarding the usage difference between GND/ CP filters. I shoot sunrise/sunset and occasionally I get blown out sky, even with low ISO and small lens opening. I've read every article related to these filters, I need a clear explanation of the difference between the two and there applications. Thanks in advance for any replies.

rmalarz Loc: Tempe, Arizona

GND filters are somewhat like sunglasses for your camera. They are usually rectangular and progressively darker at one side of the rectangle and lighter on the other. CP filters work with the polarized nature of light and darken/eliminate reflections, darken sky-with the maximum effect noted at 90 degrees to the sun. That is if the sun is in the east, the darkest sky will be to the north or south. The polarizing element of the filter is configured in a circular pattern to avoid interfering with the auto focus of most camera.

https://en.wikipedia.org/wiki/Graduated_neutral-density_filter

https://en.wikipedia.org/wiki/Polarizer#Circular_polarizers

--Bob

CWW Loc: North Jersey

Bob, thanks for the reply. Much appreciated!

rmalarz Loc: Tempe, Arizona

You're welcome.
--Bob

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

if you have a straight horizon, a GND can be a great help. But I find that shooting at base ISO and adjusting the settings to avoid blowing out the setting sun provides me with a good image as well. Also, consider using a 2 or three shot HDR. All three approaches will work in most circumstances.

amfoto1 Loc: San Jose, Calif. USA

Bob did a good job succinctly describing each type of filter's function in his response above.

IMO, when directly shooting sunrise or sunset no filter should be used. Best to avoid them entirely because ANY filter will cause added flare effects in images. There will be overall "veiling flare" that reduces contrast and de-saturates colors.... as well as "ghost flare" artifacts that the filter adds or increases in images. A C-Pol has multiple layers of glass, too, making it even more likely than most types of filters to cause flare problems when pointed directly at the sun.

Plus, a C-Pol has it's greatest effect at 90 degrees from the light source and no effect at all when shooting either 0 or 180 degrees. Shooting directly at the sun is 0 degrees. So a C-Pol is not a good idea, when shooting sunrises and sunsets. It not only won't accomplish much of anything, it's also is likely to cause other problems.

To prevent blown out skies, a Graduated Neutral Density filter makes more sense....

But a Grad ND is also likely to increase or cause flare problems in images. Further, most Grad ND are optical plastic and aren't multi-coated, increasing likelihood and severity of flare. (Note: there are glass Grad ND... but the rectangular ones are very expensive and may or may not be multi-coated. The round, screw-in type of Grad ND are glass and may be multi-coated, but are largely useless because they position their transition line right across the very middle of the filter.... and the horizon line at the same place in every shot taken with it!)

Besides, shooting digitally it's easy to get the same effect as a Grad ND without need for any filter at all. You can take two shots at different exposure settings (use camera's bracketing perhaps), then combine the "correct" portion from each in post processing. Actually, it's also often possible to "double process" a single RAW file... making one conversion adjusted for the brighter areas, another for the rest of the scene, then combine the "correct" portion from each in post processing.

Grad NDs were more necessary with film, but it always bothered me using them that the transition line on the filter was straight, when my horizons in images rarely were. There was usually a mountain, a tree, a building or something protruding above and breaking up the horizon line... which would leave me wondering whether to overlap it with the filter effect or raise the transition to start somewhere above it. Either way, it often ended up looking odd in the final image.

It's a lot more controllable, accurate and not difficult to achieve the same effect digitally in post processing. Stripping together two or more images can be done manually using layers and masks in Photoshop or similar s'ware. It also may be possible to combine the multiple images automatically using HDR software, since the principle is the same.

So, my answer to the question, which to use for sunrise/sunset is... neither. Don't use any filter at all. Shooting digitally, there are better ways to accomplish the same result.