Some people may think that in the modern era of digital photography, neutral density and polarization filters are not needed.
Okay, No. Although many filters are no longer really needed (unless you just want to save some time later), both neutral density and polarization filters provide effects that cannot be accurately reconstructed later. In this video, Evan Ranft explains why and how to use these different filters.
First, the polarizer. Usually, they are often called a way to make the sky bluer. Of course, you can do this by dragging the blue luminosity slider and saturation slider down. But that’s not all they do. They also eliminate reflections.
They can get gloss and glare from non-metallic reflective surfaces, such as rocks, shiny leaves, and even skin. Or they can completely eliminate and let you see the reflection of glass and water directly. This is why fishermen also wear polarized sunglasses. Not so, they got those very dark blue skies. So they can see through the surface reflection of the swimming fish below.
But they are not perfect. They don’t immediately improve every shot. Sometimes you don’t want a polarizer. One of the polarizers I mentioned that removes gloss and glare is the skin. If you completely remove this reflection, it can usually make the skin a little soft, even velvet like appearance. In a large number of desert scenes shot by breaking bad (especially in the last season), this polarization effect on the skin is particularly obvious.
So don’t always try to completely eliminate glare and reflection. Sometimes we want skin like surfaces to show special highlights, which look strange when they don’t exist. You can rotate the filter to get only some effects and reduce highlights, but not completely eliminate them.
Polariser may also have problems with ultra wide angle lenses. This is a simple physical fact that you can’t do anything about it. You just need to understand that it will happen and find out if you really need it.
Neutral density filters have one function, but have several meanings. Basically, they just cut a certain amount of visible light into the lens. Basically, they let you display your shutter. The more times they stop, and the more they stop. There are many reasons why you may need or need to be able to do this.
You may just want to capture an image of what happened over a long period of time. For example, clouds rush through the sky, waterfalls are blurred, or people rush through cities. However, long exposure is not all their benefits. You may be using a flash that does not support high-speed synchronization in bright conditions and has a limited shutter speed. Alternatively, you may limit the shutter speed due to video capture. Neutral density filters will allow you to achieve all of these, and they cannot simply be copied later.