Graduated ND

[slat]

When taking photos of a sunset at the beach with a GND would you use a polarizing filter to eliminate glare from the ocean?

 

[AlanKlein]

Try it with and without. See what you get. Remember, You'll lose up to 1 1/2 - 2 stops with the polarizer in addition to the GND.

 

[TCampbell]

A polarizer will have nearly no effect with the camera pointed at the Sun.

This is because as light hits any reflective surface, the light will be polarized based on the angle of reflection. The stronger the angle, the stronger the polarization.

A polarizing filter doesn't actually "polarize" the light... it "filters" the light based on the polarization of the light waves.

When the Sun is setting on the ocean, the reflection off the water is an extremely shallow angle -- which means that light isn't getting much of a polarization to it -- and that means the polarizing filter wont be very effective.

Polarizers work best when the source of the light is coming from the sides. If the light is nearly ahead of you OR nearly behind you, you'll find that they don't have a very noticeable effect.

Sunsets are a bit of a special case. For normal gradient ND filters, half the filter is clear, then you get ramping up of the darkening on the other half of the filter. This is great when the sky is noticeably brighter than the landscape as it can help tame the sky so you can increase exposure of the land for a more balanced exposure.

But with a sunset, the brightest point is near the middle of the frame... not at the top.

There's a special version of a gradient ND called a "reverse gradient ND". This filter is clear at the bottom half, but VERY dark in the center, and gradually fades in brightness as it gets near the top. It's basically designed to darken the image the most at the center (where the Sun is located).

See: LEE Reverse ND Camera Filters
Or: Daryl Benson Reverse Graduated FiltersAvailable in Neutral & Orange Densities - Singh-Ray Filters
Or: Resin Neutral Density Reverse Grad