Aurora Aperture PowerND Rear Filter Kit Review
September 23rd, 2018
Wide angle lenses and filters are a bit of a nightmare. One of the main challenges many photographers have to consider is that using anything but the bare lens involves expense, bulk, and inconvenience. Lenses with less focal lengths and smaller maximum apertures can often use typical screw-in filters, but at the cost of less dramatic angles of view and less light gathering potential. Fortunately there are some people out there who are applying themselves to trying to solve these problems, and one of them is Aurora Aperture. They have carved out a niche for themselves by making quality, innovative, and reasonably-priced filters. One of their more recent projects is the PowerND rear filter kit that tackles those lenses where standard screw-in filters are out of the question. They primarily make the PowerND kit for Canon lenses (those with a rear gel-filter holder), including:
- EF 8-15mm f/4L Fisheye
- EF 11-24mm F4L USM
- EF 14mm f/2.8L USM
- EF 15mm f/2.8 Fisheye
- EF 16-35mm f/2.8L USM
- EF 17-35mm f/2.8L USM
- EF 17-40mm f/4L USM
You can catch my full video review here:
In this case, I’m actually reviewing the kit on the Irix 15mm f/2.4 Blackstone lens that I recently reviewed. The Irix lens is unusual in that it has a wide focal length (15mm), wide maximum aperture (f/2.4), and yet can still take screw-in filters, though at a very large 95mm size. It also has a rear gel filter holder. Aurora Aperture makes this PowerND filter kit for the Irix 15mm, but also the 11mm f/4, which cannot use screw-in filters.
The traditional problem with gel filters is that they are optically uninspiring. By nature they are made of inferior materials (gelatin), which produces reduced optical performance in terms of resolution and clarity. They also often introduce color casts (typically blue or magenta depending on the manufacturer). Traditional screw on ND filters also frequently have an issue with color casts, in my experience (I’ve used a number of different filters and systems from a number of different manufacturers), and they also typically have a problem with introducing heavy vignetting. Any natural (mechanical) vignette introduced by adding something to the front of a lens gets more and more exaggerated the longer the exposure lasts.
But without filters, photographers have few options for limiting the amount of light that reaches the sensor, making long exposure shots near impossible. Long exposures can really add drama to an image, and turn a rather bland image into something far more dramatic. Long exposures are also great ways to eliminate distractions like tourists at popular spots. In a very long exposure they simply disappear. Would you believe that during this shot a man brought his dog down to drink about ten feet in front of the camera? The dog drank, moved around for about 20 seconds, and they left. No trace left in the image.
You can’t do that without a long exposure, and in that kind of light, you simply can’t create a long exposure without a neutral density (ND) filter. Think of ND filters as being sunglasses for your lens. In mild forms (like the ND8 included here), it just helps to reduce glare and can enrich colors. It can also help in using wide apertures in bright conditions. In more extreme forms, however, it cuts the light so significantly that you need a very long exposure period to produce a properly exposed image. During that long exposure a lot of dramatic things can happen. The images in this review in no way represent optimal conditions for LE (long exposure) work, and yet there is a lot of drama that has been introduced into them.
Aurora Aperture recognized the strengths of a rear gel filter system (small, no vignette, less chance of flare/artifacts) but also saw that the typical gel filters didn’t provide the optical quality necessary. So, they designed the PowerND, which replaces the standard gel filter holder (typically plastic) with the Aurora IR filter holder made from CNC aluminum alloy. They include the small screwdriver to do the quick swap and some extra little screws in case you lose a few. The screwdriver seems to have a bit of magnetizing that helps hold the little screws in place, and it made the job easy. I did it in less than 5 minutes, and that included taking a few photos during the process.
This new filter holder allows you to use Aurora Aperture’s high end PowerND filters, which are made from Gorilla Glass® like smartphone screens. Real, high end optical glass, with multi-layer nano coatings that are applied to filters for both light reduction and surface protection. These boast 128 layers of nano coating! The nano-coating provides protection against moisture, oil, dust (fingerprints), making them easy to clean. I would have liked to see a cleaning cloth included in the kit, actually, as it is always useful to have along. They are small, and, while you can grip them on the square end without any fingerprints actually interacting with the image, I still like to keep things clean.
The byproduct of this approach is impressive. There is absolutely no extra vignette introduced, and color casts are as low as I’ve ever seen. I’m hard pressed to say that any real color casts are introduced, which has not been my experience at all with ND filters in the past.
The Aurora IR filter set (PowerND) comes with a IR filter holder and four IR format ND filters in the rating of ND 8 (3 stops), ND64 (6 stops), ND 4000 (12 stops), and ND 65000 (16 stops). I would prefer an ND1000 to be included (10 stops), as that is often a sweet spot for my work. I would rather the ND65000 (which is too extreme to be used in many situations) be replaced by the ND 4000 as the upper end and the ND 1000 to be inserted into the kit. I find that the ND 4000 often requires 5 minute plus exposures at f/8 even in the middle of the day, and by my calculations it seems to behave more like a 13-14 stop reduction in light rather than 12. I’ve yet to find a situation where I felt I needed the more extreme ND 65000.
Shooting extremely long exposures will require you to enter bulb mode on your camera, and I find that a remote release like the Vello Shutterboss helps by allowing you to stray away from the camera and retain a digital readout on how long the exposure has gone.
It’s pretty remarkable how compact the PowerND kit is. The filter holder stays permanently mounted on the lens and doesn’t interfere with anything. The four filters come in a little case that is easy to bring along. The only thing to watch out for is the added risk of having your camera exposed while you swap filters on and off (this requires unmounting the lens), as you can introduce some dust or moisture if conditions are poor. I’ve personally had no problems, but I do try to be cautious. There is a little felt-like area on the IR Filter mount that allows you to slide the filters into place without scratching them.
I’m very impressed optically as well. There is little loss of detail or clarity (this photo and crop is a nearly 5 minute exposure using the ND 4000 filter).
There is next to no color casts. You can go from a fairly boring image to dramatic one by increasing the exposure time (just go to a “heavier” ND filter).
The PowerND kit from Aurora Aperture comes with the filter holder, the tools for the swap, and the four filters. It costs around $250 USD, which seems moderately expensive only because everything is so small. When you compare it to what it would cost to get an equivalent setup in a front filter holder, you realize that you would easily spend 2-3 times as much. Yes, gel filters are much cheaper, but they are also deliver dramatically poorer results. This system works very well!
Finally, here’s a few things to watch for for LE work in general. First, you need to learn to pick the right subjects for long exposure. Over a long period anything that moves will become blurred. You need to choose a static subject (rocks, buildings, etc…) that will be a constant while everything else moves around it. Secondly, hot pixels are a reality of LE work. These show up as red, for example, like in this photo:
They typically don’t last, but if they persist in other images, put the lens cap on a lens and take a 30 second exposure. It will just be black, but it will typically remap the pixels and eliminate the hot pixel issue.
Finally, the heavier ND filters (ND 4000 and ND 65000) will cut the light so much that you won’t be able to see to focus in either the viewfinder or the LCD screen, and autofocus won’t work. You have a couple of options. You can use hyperfocal techniques (look it up if you aren’t familiar), or focus with the ND8 or ND64 filter on (if the lens has autofocus it will probably still work, and, if it doesn’t, you can see enough still to focus in many lighting conditions). It’s better to do this with at least a filter on, however, as the ND 4000 and ND 65000 filters can cause some focus shift. Prefocus the lens, then carefully remove it, change the filter to the desired one, and then remount the lens. Long exposure work, like other specialized photography, requires some work to refine your technique, but the end results are well worth it! Aurora Aperture’s PowerND filter system is a great choice if you happen to own a lens that it is compatible with. Highly recommended!
More Photos from PowerND
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Keywords: Aurora Aperture, PowerND, Power ND, PowerND Review, Power ND Review, Dustin Abbott, Aurora ND Review, Canon 11-24mm, Irix 15mm, Irix 11mm, Canon 8-15mm, Long Exposure, Hands On, Filter Kit, Rear Filter, Video Test, Sample Photos, How To