Ultra Pro 82mm Variable NDX Fader Filter ND2 - ND400

I ordered this from Fanta (through Amazon) and it was about 2/3rds more expensive than here. The edge of the ring says Vivitar Series 1. It says nothing about 'UltraPro'. So I'm uncertain I'm reviewing the identical product or not. Yes, there are index marks on the ring. More importantly, the forward most part of the ring is 5mm MORE than the part that threads into your lens. This means you won't be able to install/remove the hood for your lens with this installed. If you leave the hood on, it's going to make installing this most awkward and difficult without cross threading or scratching the lens.I believe Vivitar's reasoning, however, was to avoid vignetting by making the outer-forward portion of this filter bigger. I, myself, found the swivel ring turns easily and smoothly. It's made of metal and optical glass. The threads seem well machined and don't stick, unlike some of its plastic Chinese cousins. If this is the same unit as the more expensive 'UltraPro' I just purchased from Fanta through Amazon, I wish I'd purchased from this vendor as I bought 3 (67mm, 72mm, 77mm). I'm a bit nervous/leery of sending it back under Amazon's 30-day return policy simply because I found a much better deal. I could save $46 if Amazon would accept them back--but perhaps they ding customers for returning items that aren't straight up 'defective'?HOW IT WORKS:I've played around quite a bit with linear polarizing filters and circular (CPL) ones. Wikipedia has a wonderful animated diagram explaining how CPL's work. Essentially they're a combination of a straight up linear filter stacked on a quarter-wave linear polarizing filter. The combination (with the simpler linear filter being the first the light hits) creates a kind of helix spiraling light beam pattern that doesn't defeat the functionality of modern digital cameras with their phase focusing and light metering systems. You can check on my explanation by holding the CPL up to your eye and looking at a pair of polarized eye-glasses with a little illumination behind them. If you hold the CPL in the same orientation it would be mounted on your camera, no matter which way you rotate the CPL, the light on the far side of the polarized glasses will still be visible through it. BUT, if you reverse the direction you look through it and THEN rotate the CPL, you'll see the polarized eye-glasses change from transparent to 'black'. That's because the straight linear portion of the filter is now the ultimate arbiter of how the light will be polarized before it gets to your eye. In its more normal orientation, however, it is the quarter-wave plate that is the final arbiter.So I tried the same thing with this variable NDX, and guess what? It behaves much the same way as the CPL with one important difference. If I hold the NDX in its normal orientation, leaving it wide open (minimizing any 'darkening'), it matters not which way or how much I rotate it while looking at the test polarized eye-glasses mentioned above. If I reverse it (leaving the NDX wide open), I get the very same effect described above when examining the polarized eye-glasses. However, the CPL doesn't (at least on its own) DARKEN the image when I rotate its elements relative to one another. The variable NDX does! How can this be? My guess is, unlike the CPL, the NDX doesn't use a quarter-wave plate as one of its elements. I don't think it uses two simple linear polarizing elements either. I think it uses a linear polarizing element stacked on a plate with a much smaller perpendicular wave plate than one-quarter. Perhaps it's 1/16th, I don't know. But in any event, it's small enough to effectively remove almost all the light when the two elements are rotated 90 degrees to one another. This approach might allow the phase focusing and metering of your digital camera to continue to function even with a variable NDX on it.Them's my thoughts and I'm sticking to them until someone offers a more plausible explanation. I hope you appreciate the physics of my explanation as understanding light mechanics may help you be a better photographer. This is worth owning although admittedly I'd like to own it for 3/8ths less that what I do. I haven't tested it for aberrations/artifacts. But having the dynamic range of a video camera overwhelmed and the white balance screwing up the color saturation is a pretty serious 'aberration' in its own right.

I ordered this from Fanta (through Amazon) and it was about 2/3rds more expensive than here. The edge of the ring says Vivitar Series 1. It says nothing about 'UltraPro'. So I'm uncertain I'm reviewing the identical product or not. Yes, there are index marks on the ring. More importantly, the forward most part of the ring is 5mm MORE than the part that threads into your lens. This means you won't be able to install/remove the hood for your lens with this installed. If you leave the hood on, it's going to make installing this most awkward and difficult without cross threading or scratching the lens.I believe Vivitar's reasoning, however, was to avoid vignetting by making the outer-forward portion of this filter bigger. I, myself, found the swivel ring turns easily and smoothly. It's made of metal and optical glass. The threads seem well machined and don't stick, unlike some of its plastic Chinese cousins. If this is the same unit as the more expensive 'UltraPro' I just purchased from Fanta through Amazon, I wish I'd purchased from this vendor as I bought 3 (67mm, 72mm, 77mm). I'm a bit nervous/leery of sending it back under Amazon's 30-day return policy simply because I found a much better deal. I could save $46 if Amazon would accept them back--but perhaps they ding customers for returning items that aren't straight up 'defective'?HOW IT WORKS:I've played around quite a bit with linear polarizing filters and circular (CPL) ones. Wikipedia has a wonderful animated diagram explaining how CPL's work. Essentially they're a combination of a straight up linear filter stacked on a quarter-wave linear polarizing filter. The combination (with the simpler linear filter being the first the light hits) creates a kind of helix spiraling light beam pattern that doesn't defeat the functionality of modern digital cameras with their phase focusing and light metering systems. You can check on my explanation by holding the CPL up to your eye and looking at a pair of polarized eye-glasses with a little illumination behind them. If you hold the CPL in the same orientation it would be mounted on your camera, no matter which way you rotate the CPL, the light on the far side of the polarized glasses will still be visible through it. BUT, if you reverse the direction you look through it and THEN rotate the CPL, you'll see the polarized eye-glasses change from transparent to 'black'. That's because the straight linear portion of the filter is now the ultimate arbiter of how the light will be polarized before it gets to your eye. In its more normal orientation, however, it is the quarter-wave plate that is the final arbiter.So I tried the same thing with this variable NDX, and guess what? It behaves much the same way as the CPL with one important difference. If I hold the NDX in its normal orientation, leaving it wide open (minimizing any 'darkening'), it matters not which way or how much I rotate it while looking at the test polarized eye-glasses mentioned above. If I reverse it (leaving the NDX wide open), I get the very same effect described above when examining the polarized eye-glasses. However, the CPL doesn't (at least on its own) DARKEN the image when I rotate its elements relative to one another. The variable NDX does! How can this be? My guess is, unlike the CPL, the NDX doesn't use a quarter-wave plate as one of its elements. I don't think it uses two simple linear polarizing elements either. I think it uses a linear polarizing element stacked on a plate with a much smaller perpendicular wave plate than one-quarter. Perhaps it's 1/16th, I don't know. But in any event, it's small enough to effectively remove almost all the light when the two elements are rotated 90 degrees to one another. This approach might allow the phase focusing and metering of your digital camera to continue to function even with a variable NDX on it.Them's my thoughts and I'm sticking to them until someone offers a more plausible explanation. I hope you appreciate the physics of my explanation as understanding light mechanics may help you be a better photographer. This is worth owning although admittedly I'd like to own it for 3/8ths less that what I do. I haven't tested it for aberrations/artifacts. But having the dynamic range of a video camera overwhelmed and the white balance screwing up the color saturation is a pretty serious 'aberration' in its own right.

Optical quality of this filter is decent--I did some side-by-side comparisons with and without and it seems to not degrade image much. I wish there was a multicoated version, as this one appears to be uncoated, which results in more flare and less contrast. You would expect to pay more for coatings, however. The very highest density is unusable due to the uneven purple color. I can make about a 6 stop change before I notice any image degradation. By 7 to 8 stops, you start to notice uneven bluish vignetting, and by the 9th stop, it's just ridiculous. So maybe this is effectively a ND2-128 variable filter, or something in that range. It still serves me well, as I mostly want this for doing daytime video wide open on a fast (1.4) lens, using 1/60 (180 degree) shutter speeds. These drawbacks are typical of a variable polarizer, and any filter at this price, so these do not affect my rating very much, although the seller's claims of variable range are a bit overzealous or dubious.What I really don't understand, and what made me rate this lower, is why does the lens come with a 55mm back thread for my camera, but a 58mm forward thread for the lens cap? Could it be to make the front wider to not obstruct wide angle lenses? That doesn't matter on my nifty fifty, but what is affected is that I can't put my lens cap on with the filter in place. Luckily, I had a 58mm lens cap laying around, but you'd think that would be stated clearly in the product description. Did I miss that? So really, if you buy this lens, you need to figure out what the front thread diameter is, and factor in the purchase and hassle of an additional lens cap if you're going to be using this a lot.