Ever since the Lee Big Stopper came out, really dark neutral density filters have been quite the thing for long exposure photography. Formatt Hitech has been putting out some interesting ND filters in the last couple of years, the ProStop IRND series and the Firecrest series. Although I set out to write about only the Firecrest filters, I realized that I needed to include a bit of a review of the ProStop IRND as well because of the necessary comparison of the two sets.
Note that I’m using the Lee filter holder, so I’ve been using the four inch/100mm square filters. They do come as screw-on filters, but I’ve never used them.
The ProStop IRND (infrared neutral density) was a step toward trying to correct the colour cast of really dark ND filters. The idea was that cutting the infrared contamination should render the colours better, particularly in the shadows. So I ordered three of different strengths (three, 6, and 10 stops) when I decided I wanted to fiddle around more with long exposure photography. The filters themselves are 1.5mm thick resin, and to compensate for their thinness they added a foam gasket to ensure a tight fit in the filter and help prevent light contamination. Multiple filters also means that you can stack them up to increase the light reduction.
So how do the ProStop IRND filters stack up? Well, they certainly work to cut light, and I noticed no particular colour cast to the three and six stop filters. On the 10-stop filter, though, there is a distinct blue cast with some wonky magenta as well, so “neutral” it is not. So I could use the filter, but realistically everything had to be converted to black and white in order to be useable.
Of course, no sooner had I received the IRND filters than Formatt Hitech came out with a newer, zippier ND filter: the Firecrest 16, an ND filter that boasts 16 stops of light reduction. Simultaneously miffed and curious, I ordered one. The Firecrest filter is a 2mm thick piece of Schott Superwite glass, with “a carbon metallic coating used to create hyper neutral NDs.” Unlike the ProStop IRND filters, it does not have a foam gasket; the glass is thick enough to fit snugly in the Lee filter holder.
And how is it to use the Firecrest 16? Sixteen stops of truly neutral ND goodness. I could squeeze out much longer exposures with this filter without having to stack filters; so far I’ve experimented with up to 16 minutes of exposure time. And just as importantly, I could discern no colour cast to the resulting images. That’s right, no colour cast. No strange blues or magentas in the images.
There are two main downsides to the Firecrest 16, and they aren’t exactly all that bad. One is the sheer strength of the filter: it lends itself best to shooting near mid-day. I’m a patient man, but I don’t think I want to put in a half-hour or more to a long exposure (I’m not certain how long the battery on my camera would last for a long exposure). The other is that it is glass. If you are a klutz, this can be a problem (my first copy of this filter ended up dying an ignominious death because I am quite definitely a klutz).
A solution to the first problem has arrived, though: Formatt Hitech has started putting out Firecrest filters with lower strength. As of earlier this year, they had put out 10 and 13-stop Firecrest filters, though now they’ve gotten around to putting them out in 1-9 stop versions as well. So I snapped up the 10 and the 13 while I was replacing my 16 anyway. So far, I have to say that the 13-stop filter is my favourite of the bunch. Why? It comes back to using the Lee filter holder (actually, the Universal Hood – see my previous review). To cut down on vignetting, I only have two slots on the Lee holder, plus the circular polarizer ring. If I’m shooting a landscape, I often end up with a graduated neutral density filter in one of the slots; with the GND and CPL, to get about 16 stops I only need a 13-stop filter. Any darker of an ND filter and I’m ending up in the half-hour and beyond territory of shooting.
Since I got the Firecrest 10-stop filter, I was able to do an apples-to-apples comparison with the ProStop IRND 10-stop filter. As you can see from the pair of photos to the right, the ProStop IRND filter (top) has a blue cast, whereas the Firecrest filter (bottom) does not. I did nothing other than correct for lens distortion in both images and ensure that both were set to the same white balance (cloudy) in Lightroom. The colour cast can be mostly, but not entirely, corrected in Lightroom using the White Balance Selector tool; it will retain a light magenta cast instead.
All told, I’d recommend getting the Firecrest filters over the ProStop IRND filters, especially the stronger ones, even though the latter have come down in price since the introduction of the Firecrest filters. The colour distortion is just too much of a pain to deal with, if you ever want to produce colour long exposure images.