A previous discussion briefly touched on a few scenarios where a photographer can use an ND filter. In this discussion, I will walk you through a hypothetical (but very much real-life) situation where you (the photographer) can use an ND filter to accentuate your work.
Let’s say that you’re on a jungle trail and you’ve to stumble upon this beautiful brook that runs through a wooded area of the jungle. You decide to set up and capture a long exposure shot of the scene. There are many challenges to taking a long exposure shot of such a scene.
First, with the available light, a long exposure shot will quickly result in an overexposed image. So it goes without saying that you need an ND filter to balance the exposure.
However, the question is, what ND filter strength should you use?
I have recently discussed Optical Density Numbers and Filter Factor Numbers frequently used on ND filter packaging. If you’re confused about how these translate into stops of light reduced, you can refer to those articles.
With ND filters, you now have many creative photography possibilities opening up. With ND filters now taking center stage, you can use them to decrease the shutter speed allowing light to enter the camera over a longer period.
Let’s say that you’re standing in front of a historical monument. It’s filled with people, and you can’t get a clean shot of the monument as if it’s devoid of people. One way to do that would be to reach the spot before anyone else does so that you can get the shot you want. The other option could be to use an ND filter—a strong one, at that.
I recommend using at least a 10-stop ND filter. that would reduce the light entering the camera by 1/1024 of the original amount. How does that translate into shutter speed?
Well, let’s say it was moderately overcast, so the actual shutter speed recommended by the camera was 1/500 sec. With a 10-stop ND filter, you can now reduce the shutter speed to 2 seconds.
With this, you can now blur out any movement of people in the scene, and the image will appear devoid of people. In the ideal scenario, you can stack multiple filters to accentuate the effect and dial in an even slower shutter speed.
Of course, now you will need a tripod to secure your camera. Without a tripod, your image will turn out blurry. So that’s one of the disadvantages of using an ND filter.