The problem with ultra-wide lenses is that a bulbous front element makes it impossible to attach a filter directly to the lens. A tried and tested method to create more space between lens and filter through the use of a filter holder and a lens adapter ring. Systems such as the Wonderpana by Fotodiox and the SW-150 by Lee make the use of all sorts of filters available for photographers with deep pockets. Like the enormous filters themselves, these systems are often expensive and only attach to one lens. Enter STC with a 6-stop ND filter that you could use with the widest of lenses, and for just 80 bucks.
It's essentially the same system as the STC Astro-Multispectra filter, reviewed here. The idea is that you lock up the mirror, put in the filter and prevent the mirror from coming down, while never touching the delicate sensor at the heart of the camera. This nifty approach enables the use of filters on lenses without filter threads.
https://500px.com/photo/170666063/to-rid-the-deadwood-by-daniel-laan
A 6-stop ND filter is ideal for use under broad daylight to slow down waterfalls enough to get them nice and streaky, without blurring them completely.
https://500px.com/photo/157075245/holiday-by-daniel-laan
Another great time to use a 6-stop is right before sunset, when the sun is about to dip below the horizon and you wished the water was flat as a mirror.
STC claims that the ND64 filter is free of the dreaded color cast, due to its water and grease resistant coating and "Simulative Linear Calibration." The filter is just 1mm thick and features the high quality Schott B270 optical glass from Germany.
The 80 dollar neutral density filter weighs just 9 grams and is available for Canon and Nikon full-frame bodies.
[via STC Optics]
Take my money...
Maybe I don't understand how this works. Do you have to try to focus and compose with the filter in place??
Okay...so I checked out their website. Basically, you have to use live view and focus and compose with 6 stops less light. AND unless you want to shoot everything with it, you'll have to put it on and take it off in the field...probably multiple times. It wouldn't take much of that to decide the other systems are worth the money.
I feel you. The process of attaching and detaching lenses is finicky enough as it is and something I personally try to minimize in the field, especially near waterfalls. Wide-angle lenses should all have the abillity to use drop in filters like the longest telephoto lenses. :)
You don't have to take the filter out. Just use this technique: https://www.youtube.com/watch?v=2b6I4RVqUNo
Most (not all) usage of extreme nd filters imply landscape/field work. In the best scenario in a studio, I would be hesitant at exposing my sensor to various problems like dust or moisture, in the field, they are a given . . . in other words this is a very risky solution. One that I would never try. Yes, super wide manufacturers SHOULD have a rear filter option. This idea works, but I wouldn't touch it . . . ever.
If only we could have the option of flipping up the mirror but keep the shutter closed...