Review / Tiffen Variable Neutral Density Filter

I don't talk much about gear. However, this I thought I should talk about. If you're a landscape photographer (probably, if you've landed on my page), you either own or are thinking about buying a neutral density filter.

I've had a Tiffen Variable Neutral Density (ND) filter in my camera bag for a while. I've not used it much since my polarizers cut 2 stops of light and that's typically been enough. This past weekend, I decided to give this filter a proper field test. There's two parts to this review. The Tiffen part and the variable ND part.

A Little Background

For those that may be new to the concept of a neutral density filter, it's a dark piece of glass put between your lens and the scene you're shooting. An ND filter cuts down on the amount of light coming into your camera, allowing longer shutter speeds, without having to narrow your aperture. You can keep the aperture set for the depth of field you want and use an ND to take a longer exposure.

These filters are used to get pleasing "blur" effects for things in motion in the scene. Think clouds streaking across the sky, cars zipping by leaving light trails, smooth silky water, and so on. There's other uses too, but smoothing motion is the most interesting to me as a landscape shooter.

There's a variety of ND filters. If you've ever seen a photographer with a square-shaped front on their camera, it's probably a glass plate filter of some kind. The glass plate NDs I've seen are single density. 2 stop, 4 stop, 10 stop, etc. Each plate cuts a specific, fixed amount of light. A holder that fits around your camera lens is also required. There are also ND filters that screw on to the front of your lens, like the Tiffen one I'm talking about here. My model is a variable ND filter, ranging from 2 stops to 8 stops of light. You control how much light enters the camera by rotating the outer ring.

With the context set, let's get into the review.

The Tiffen Part

Wide front element prevents vignetting... and lens hoods.

I chose Tiffen because my polarizer are from Tiff and I've been happy with them. The filter is well constructed and durable. It's vey good quality. I also chose this particular one because the outer piece of glass is larger than the screw mount. This helps to reduce vignetting. A side effect of this is I can't use my lens hood while this filter is on.

The only complaint I have is that the markings on the outer ring are not precise measures. For example, I can't rotate the filter to exactly 4 stops of light. Straight from the description on B&H Photo:

"It should be noted that the calibration marks on the filter ring are to be used only for reference and should not be regarded as accurate settings for specific densities."

That's a limitation and introduces a little guesswork into determining the right shutter speed. Other brands I read up on (Hoya, B+W, Bower) do not call out this limitations. Maybe the other brands have it, maybe not. 

The Variable ND Part

The convenience of 2-8 stops of density at your fingertips is the key advantage. Attach one filter and simply rotate to taste. It's a cost effective solution, too. The cost of a single variable ND is much lower than 7 glass plates. And that's about where the advantages end.

There are several disadvantages:

• I can't use the filter with my polarizer. The polarizer should be the first filter the light hits – the one on the outer most edge of a filter stack up. That's clunky with a variable ND filter. One has two rotating elements in the filter stackup. As you're rotating one, you're trying to keep the other stable. Clunky. Quirky. A headache. 
  
  There's also the physical mechanics. Vendors have to make a design choice vendors for a variable ND. Make the front element wider to cut down vignetting, trading off the ability to affix another filter. Or, keep the variable ND the same diameter, but introduce more vignetting. Either setup is flawed.
   
• Auto-focus can be a challenge. This isn't really a problem in bright daylight. Rotate the variable ND to it's lowest density, focus, and then rotate to the desired density. In low light, such as civil twilight, you need to focus before affixing the variable ND. It's all to easy to bump your focus ring. It's much simpler to slide in a glass plate.
   
• Over-rotating and getting vignetting. Even with the wider front element, or models that are designed thin to reduce vignetting, you can over-rotate and get pronounced vignetting at the corners of the frame. And in low light, it can sometimes be hard to detect you've pushed the filter too far.

Again, none of these pros/cons are pure and specific to Tiffen. The drawbacks are a direct result of the variable ND design. It's convenient, but overall limiting.

The Takeaway

Overall, I'm not unhappy with the filter. It has uses, and I'll use it for now since I have it. Although I can't recommend a variable ND filter with any any level of fervor. The convenience of 6 stops of density with the turn of the wrist is attractive. And the price point is pretty good. However, for me, the drawbacks significantly outweigh the convenience.

For future ND needs, I'll go the glass plate route. However, it's lower on my gear list. I'm in the market for a new setup... but that's another tale for another day.