Choosing the right ND FIlter

When you start to progress in your photography you will inevitably dive into the world of ND Filters. For me, this started when I was working with a skilled and established photographer I knew.

We went out to a Landscape photography shoot one evening at sunset. After hiking for a little while we eventually found a spot on a rock and he started to pull out a very large, dark black filter to put on the end of his lens. Not wanting to look like the newbie I didn't say anything and attempted to get a longer exposure on my own. Stopping my lens down to its absolute max F stop I was surprised to learn I could only get around 1/25th of a second for my longest exposure.

If you are anything like me when I first started this was a surprise. You know that anything past F16 is fairly dark and you cannot drop your ISO past its lowest native setting, which is usually 100. So not wanting to be clueless anymore I decided to ask just what that filter was. Being a photographer he, of course, went on a 15 min speech about how it was an ND blah blah blah that would provide a certain number of stops of darkness to allow for a longer exposure. All I cared to remember, and still do to this day, is that it makes the light coming into your lens that much darker so that you can have a longer shutter speed. While to some people it is nice to know the number of the ND because it provides a reference for how much darkening you will need. I am more of the type to just buy a super dark one and learn from there.

But in order to provide a better understanding of what these mean let me dive into it a little bit. There is an equation to figure out the amount of light that your ND filter is stopping down but what you really need to know is that an ND2 is 1 stop of light, an ND4 is 2 stops of light, and an ND16 is 4 stops of light. I have never needed anything smaller than an ND 16 for my photography. 1 stop of light darkening will not give you a whole lot of darkening, nor will 2 stops. I find these to be a real waste of money honestly just because I use them so infrequently that they would never get pulled out of my bag. They can be very useful if you are a portrait photographer and are just needing micro-adjustments for your exposure. Say you are using flash outdoors around sunset and you need to stop down the light a little because you want to use a larger F-number to give a more shallow depth of field. You wouldn't need to use a large ND filter because you couldn't see through it to compose your image and this would give you the small amount of darkening you need.

A large number ND filter, like say ND16, or ND1000 would be used for tripod work like landscapes or cityscapes where you want to keep the shutter open for really long lengths of time. I find that these two filters generally keep me right where I want to be with my exposure at both sunrise and sunset. There are much darker ND filters that provide upwards of 15 and 20 stops of darkening and these are going to be niche filters for those who are trying to get really long exposures for architecture or stacking for cloud movement. I would like to eventually try out some of these filters in my photography but I find that when you get into super long exposures you run into issues of hot pixels and lower sharpness.

Before I go on to recommending my favorite ND filter I am going to talk about the issues with ND filters and variable ND filters. First, let's get variable ND filters out of the way because they are going to come up when you dive into the world of long exposure. Variable ND filters are great tools but for still photography, I cannot recommend them as they are very hard to use and can render strange artifacts in your photos. Maybe they have gotten better today but the variables that I Have all have the dark X that they are known for. The X is a point at which the ND filter is transitioning from its darkest to its lightest shade and will place a strange dark black X across your image. much of the time this is not noticeable to the human eye but it is noticeable from the camera sensor. There is no way to fix this and when you are on the clock with a setting or rising sun it can be the difference between getting the shot you want and missing the light completely.

Solid ND filters are not perfect, nor are graduated ones for that matter. They can cast colors, cause your image to become less sharp and even introduce a vignette into your image because of the thickness of the metal ring. Much of this comes down to the quality of the glass you are using but understand that any type of glass you put in front of your lens will cause you to lose image quality. Even the most expensive UV filter will cause you to lose sharpness and contrast in your image. I don't care how good the marketing is you will lose some image quality by putting on a filter, it's just how physics works. But there are filters out there that have been designed to minimize this to a point that you will not notice and it can be easily compensated for when editing your photos. Color cast is by far the worst thing you will encounter when using an ND filter. Generally, your images will become much cooler when you put an ND on. This can make it extremely hard to white balance and can throw off auto white balance to give you some crazy colors. Just be aware and do your research to understand what kind of shift you can expect and learn how to deal with it.

Now if all of that has not scared you off using an ND filter its time I give you a recommendation and wrap this up. I have quite a few brands of ND filters but my favorite by a long shot is the X4 by Breakthrough Photography. Their glass is absolutely beautiful and provides little color cast issues and sharpness loss. The edges of the filter have been specially designed to make them easy to take on and off, even if you tighten them down too much, and they are razor thin so I have had no issues with vignetting on my lenses. You can find more at www.breakthroughphotography.com, I have the X4 filter which is an on the pricier side but I wouldn't trade it for the world.

I didn't talk about the drop in filters in this post because I have never used them nor do I Want to use them in my photography. They are very delicate, require special mounts and carrying cases and are just too much for me to deal with. Maybe someday if I ever cross over to the dark side but right now I will be sticking to my screw-on filters. No matter what style you choose make sure they work for your workflow and how you shoot. You can spend so much time fiddling with filters and holders that you miss a moment or the light passes you by and that is ultimately the worst thing you can do to your photos.