- What is a Variable ND Filter?
- Variable ND vs Fixed ND
- Pros of Variable ND Filters
- Cons of Variable ND Filters
- Using Variable ND Filters
- Best Aperture for Landscape Photography
- How To Improve Landscape Photography
- How To Photograph Rivers and Streams
- How To Take Good Photos With a Kit Lens
- Mountain Photography Tips
- Circular Polarizer Do’s and Don'ts
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Neutral density filters are amazing tools for photographers needing extra control over exposure conditions or wanting to use some special techniques for creating interesting images.
Variable ND filters are preferred by many photographers while others like ND filters with a fixed value.
Let’s discuss the benefits and detriments of using the former - variable ND filters.
Table of Contents
What is a Variable ND Filter?
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Neutral density filters add density to the light path when taking a photograph. Adding density is basically the same as subtracting light. ND filters attenuate the intensity of the light reaching the film or sensor and do it without affecting any colors.
The term variable in the name variable ND filters refers to the amount of that attenuation being able to be changed by the user. The mechanism used is actually quite similar to circular polarizers, but instead of affecting the light for a polarizing effect, two polarizing layers are used together with the result being a significant darkening of the light getting through.
Variable ND vs Fixed ND
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Neutral density filters give photographers the option of using the f-stops and shutter speeds they need for certain effects while in lighting conditions that wouldn’t normally support those settings.
For instance, if you wanted to use a very fast aperture for limiting depth of field, but the scene’s light intensity would’t let you there no matter how much you played with the Exposure Triangle, an ND filter can get you into that aperture.
Another example would be trying to get a long enough shutter speed to intentionally blur motion in moving parts of the scene such as water, clouds, or people. In order to take advantage of that effect, sometimes you need a very long shutter speed. So, again, the ND filter gets your exposure triangle into the right area.
For many of us, when we first thought of using an ND filter for those reasons, we went with the most extreme attenuation we could find. As we got used to using ND filters, we realized that we don’t always want a huge ND factor, something a little or a lot less would work for this particular image.
So you have two ways of tackling the issue of needing different ND factors for different subjects, needs, or situations. One way is to buy several ND filters of different strengths. The other way is to buy variable ND filters that cover the range you want.
Either way works, though purchasing several ND filters at once could add up pricewise. Variable ND filters that deliver great results can be much more cost effective. An example of a high quality variable ND filter is the Haida 82mm NanoPro MC Variable Neutral Density 1.2 to 2.7 filter which covers a range from 4 to 9 stops of attenuation.
Haida filters are multi-coated on both sides of all glass elements to reduce reflections and flare, ensuring accurate color light transmission and good contrast. The elements are optical glass so no loss of sharpness for your fine lenses. The filter rings are high grade aluminum which resists binding due to temperature extremes.
Pros of Variable ND Filters
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There are two huge plusses in the case for variable ND filters, cost and versatility. While variable ND filters may cost a little bit more than a fixed value ND filter, when you add up the price of 4 or 5 filters needed to cover the range in a single variable ND filter, the savings can be significant.
In the long run, though, costs of our gear are absorbed, so it’s not always as big a factor as we might first think. That versatility aspect, though, can be huge when shooting in the field under changing lighting conditions.
Changing and challenging lighting is likely going to be the normal situation when we’re using these variable ND filters. Since we are probably going to use our ND filters for outdoor photography of some type. It could be a landscape, seascape, cityscape, or environmental portraiture, all of these are outdoors photography.
Another plus or pro factor is convenience of storage and travel with our filters. Since we have just one filter to account for, we can easily fit in with our other gear and also not worry about scratching the elements against each other.
Cons of Variable ND Filters
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There is only one big con to consider about using variable filters, and you can get around it with minimal effort. The con is that variable ND filters use polarization effects to vary the amount of attenuation.
How is that a con? I’m glad you asked. Because if we’re using these filters outdoors or in some other challenging exposure and lighting conditions, won’t we want to be able to use polarization? Sure, but how much of each effect is desired can become a balancing act of sorts.
The proper position or orientation for the ND attenuation we need may not be the same position for any polarization effect we want to have in addition. Or, we may not wish for any polarization at all.
If we constantly find ourselves in this type of situation, a fixed ND and polarizer or a combination fixed ND with C-POL may be what we should use. It’s not a problem that is likely to come up often at all, but if it does, you’ll just have to adjust either the filter or your expectations for that image.
Using Variable ND Filters
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Variable ND filters will be a very useful addition to many photographer’s gear bags. They are especially useful for photographic effects that depend on settings affected by the Exposure Triangle. Selective focus that needs a wide open aperture, or blur effects that require long shutter speeds.
You will find other valid reasons for taking advantage of the properties and features of variable ND filters once you take out into the field on your next photo shoot.