Here’s how to figure out which ND filters you need

If you need ND filters, it may be a tough choice which ones to buy since there are so many of them in the market. And if solid ND filters are what you prefer, how do you know which ones you need? Let Griffin Hammond help you with that. In this video, he explains how solid ND filters differ and how you can calculate which one would be perfect for your current shooting situation.

Griffin uses three solid ND filters in different lighting scenarios. These filters are labeled in different ways:

• Optical density (the darkness of glass): 0.9, 1.8, and 3.0
• F-stop reduction: 3-stop, 6-stop, and 10-stop
• ND number: ND8, ND64, and ND1000

But if you have several ND filters, how do you choose the right one? Griffin applies some general rules: on a regular cloudy day, he uses a 3-stop filter. On a bright sunny day, a 6-stop filter is usually his choice. He uses a 10-stop filter only for timelapse videos, because they sometimes require shooting at slower shutter speeds in bright sunlight.

Other than these general rules, there is a more precise way to calculate exactly which ND filter you should use. And in this situation, it’s best to observe the f-stop reduction number of the filter. Start by setting your aperture, shutter speed and ISO to what you’d like to be shooting at. If you end up with an overexposed photo, now is the time to count how many stops it takes to get a proper exposure. Close the aperture gradually and count how many stops of light you reduce before you reach the ideal exposure.

Let’s say you need to stop down by three stops – then you can use a 3-stop filter and get back to your preferred camera settings. If you need to stop down by, say, five stops, you can use a 6-stop ND filter and double the ISO once you set the aperture and the shutter speed. Make sure to watch Griffin’s video for a demonstration, as the visual example always makes things much clearer.

You can find really cheap ND filters, but the low price is often a reflection of low quality. On the other hand, they can come with a pretty high price tag, too. Griffin recommends 3-stop Hoya NDX8 ND filter, which costs $39 and is a very good value for money.

“Filters are like wine,” Griffin says, and I like this comparison. You don’t need too much money to get something good, but still, choosing the cheapest option there isn’t a good idea. I’d add that, just like the cheapest wine, it can give you some headache.

[How to figure out which ND filters you need | Griffin Hammond]