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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Variable ND filters

Stephen Pruitt

Stephen Pruitt

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Hi there . . .

How good are those variable ND filters that you see from time to time on DSLR cameras? Using the Birger, and not having smooth iris control, I could see using a variable ND to get me to a similar spot in some situations (dialing the ND back as you move from outdoor to indoor, etc.). I have never actually looked through one, but I am curious if they are a piece of crap (which is my prior assumption) or if they really are a revolution in ND technology.

Thanks!

Stephen
 
Most of them are overpriced... Quality varies from complete junk to decent for SLR filters. In reality, they are just two circular polarizers where one remains stationary and the other rotates to give variable amounts of light blockage. Stick two circular polas in a mattebox, one in a stage that rotates. There ya go.
 
Hey Stephen just buy the best there are and you are fine. I use em all the time even on some commercials. Just don't stop them down to the max and it's all good. I just say Epic, Canon glass and varial NDs. You can't go any lighter. I realy looking forward to that.

Tim
 
I use a Singh-Ray ($350-$450 / 77, 82mm) and have been happy with it, although I have used it sparingly and haven't done any strict testing. I have not, however, noticed the chromatic problems mentioned by some with vari-nd's

http://www.singh-ray.com/varind.html
 
Years ago I shot a spot on the Panastar where we ramped from 24fps to 120fps in the same shot (a cyclist stopping and dousing his head with water and shaking his head and drops flying.) Panavision matched the motor on the spinning polarizing filter to the camera speed so the exposure stays constant without changing depth of field. The effect works flawlessly and basically it's just two polarizing filters. So two good polarizers will achieve what you want when you rotate one of them. When they are at 90 degrees to each other they effectively block all light, almost, depending on the quality (the fineness of the diffraction grating) of the filters. Hope this helps.
 
I've had a signray 77mm vari thin for a few years and love it..... you will get some IR contamination if you stop it down past the last notch... but I've been pretty happy with it shooting my RED/birger/canon ef 35, 24, at f1.4 in daylight ... iso 320 180' shutter.

here's a R3D from a few weeks ago... ef 35mm f1.4 with varind
http://www.chriswitzke.com/red/redvari.zip
 
My experience echoes those of others here ... they are not crap, they aren't new technology.

Like any filter you have to be careful of quality issues. You wouldn't use a crappy circular polarizer right? Why use two?

I tend to recommend that you try before you buy for all filters.
 
Great feedback guys. . .

So NOW the question I have is this: Why did I spend $2000 on a bunch of (5.65 x 4) Formatt IR+ND filters from 0.6 to 1.8 when I could have done the very same thing for $500 with an 82mm pola-pola and an 82mm round hot mirror? Alas. . .

Stephen
 
Stephen Pruitt said:
Great feedback guys. . .

So NOW the question I have is this: Why did I spend $2000 on a bunch of (5.65 x 4) Formatt IR+ND filters from 0.6 to 1.8 when I could have done the very same thing for $500 with an 82mm pola-pola and an 82mm round hot mirror? Alas. . .

Stephen
Click to expand...

Dunno. That's why I got the Singh-Ray in the first place.

But a mattebox looks really cool on the front of your camera and anyone who's a REAL filmmaker ALWAYS has one mounted. ;-)
 
Stephen Pruitt said:
Great feedback guys. . .

So NOW the question I have is this: Why did I spend $2000 on a bunch of (5.65 x 4) Formatt IR+ND filters from 0.6 to 1.8 when I could have done the very same thing for $500 with an 82mm pola-pola and an 82mm round hot mirror? Alas. . .

Stephen
Click to expand...

Oh ... because I think the less you can put between the sensor and the subject the better off the image is.

Oh, and if you have two polarizers on to use as a variable ND ... putting a third on to kill the reflection of the car windshield causes issues.

No question a selection of ND filters is a far better choice than an Variable ND.

In fact, given a full warehouse of cinema toys, I'd probably pull the variable ND out only in situations like Richard Foster wrote about ... where you want to vary levels of ND in shot.

Of course if you are on a budget ... dropping a few hundred on a good variable ND can delay the expense of that big filter box you have started on for a while.
 
Stephen Pruitt said:
Great feedback guys. . .

So NOW the question I have is this: Why did I spend $2000 on a bunch of (5.65 x 4) Formatt IR+ND filters from 0.6 to 1.8 when I could have done the very same thing for $500 with an 82mm pola-pola and an 82mm round hot mirror? Alas. . .

Stephen
Click to expand...

I recently shot several national spots using variable NDs on Canon glass. I was shooting live action stop motion stills so please don't jump on me for using Canon. The one I used as Lightcraft Fader ND. Performance was just OK in the middle of it's range, and poor at the extremes (near min and near max). The biggest problem I saw was some chromatic aberration and significant image softening. Because we were shooting exteriors and had to motor through 250+ setups a day, Variable ND was the only option to get through the day and that efficiency out weighed the downside.

Last week, I got the new Tiffen Variable ND. Preliminary camera tests in stills mode indicate the same characteristics of unusable banding at near minimum and maximum, but much better performance in regards to softening (in other words no losing as much apparent resolution).

These things can be a really great tool when time and space are an issue. But beware of their limitations.
 
Okay. . . that's good to know, Bill. :-)

Unfortunately, I couldn't unload the mattebox, anyway, as we're often struggling with lens flares. But, you're right. We look professional. Even if we're not.

Bottom line: If I had known about the darn thing, I would have gone that direction. No doubt about it.

:-(

Stephen
 
Stephen Pruitt said:
Okay. . . that's good to know, Bill. :-)

Unfortunately, I couldn't unload the mattebox, anyway, as we're often struggling with lens flares. But, you're right. We look professional. Even if we're not.

Bottom line: If I had known about the darn thing, I would have gone that direction. No doubt about it.

:-(

Stephen
Click to expand...

No offense, Stephen. Just joking and not really pointed at you. I understand that it's standard equipment for almost all at the high end and useful to many in the middle, but it may not be absolutely necessary, even though many will say that it is and many have bought them for that reason alone...or because they look really cool!
 
Thank you very much for supplying that Christopher. Have you used it with a hot mirror?
 
Bill Goehring said:
No offense, Stephen. Just joking and not really pointed at you. I understand that it's standard equipment for almost all at the high end and useful to many in the middle, but it may not be absolutely necessary, even though many will say that it is and many have bought them for that reason alone...or because they look really cool!
Click to expand...

You know a DP is professional when you seem them choose to take the mattebox off just because they aren't using it.

Either its a tool, its a toy or its a fashion accessory.

If its a tool, then put it away when you are done working.

If its a toy put it away when you are done playing.

If its a fashion accessory, then hanging around being useless but looking cool is its function, so leave it on the rig so it can earn its rental.
 
Stephen Pruitt said:
Great feedback guys. . .

So NOW the question I have is this: Why did I spend $2000 on a bunch of (5.65 x 4) Formatt IR+ND filters from 0.6 to 1.8 when I could have done the very same thing for $500 with an 82mm pola-pola and an 82mm round hot mirror? Alas. . .

Stephen
Click to expand...

Because it's still better to use ND's when you can, better optically.
 
Fashion accessory. Definitely.

:-)

Actually, we often take the mattebox off when we don't need it, as it just gets in the way. Still, I gotta say, nothing makes a camera look better than a cool mattebox.

:-)

Thanks for all the great comments, guys. I guess I'll keep all those ND filters and just pick up a variable for those inside/outside shots.

And Paul, I'm certainly not going to rag at you for using Canon glass. That's all we use. Two features down. Another one on the way. All Canon. All the time.

But, then again, we're not professionals.

:-)

Thanks guys!

Stephen
 
A mattebox is not always necessary. Sometimes it is. It's often a misunderstood tool amongst a lot of new shooters. Anyway, that's not really what we're talking about in here.

Single ND's are always, ALWAYS better optically than using a vari-ND pola combination. But the latter has some real advantages. I tend to use vari-NDs a lot when I do live event / EFP type shooting. Snowsports is a great example of where to use vari-NDs, especially if changing location a lot or making a lot of indoor/outdoor transitions, that sort of thing. Many times simply operating the camera iris is not the way to go.

Lens selection plays a role in how you would apply vari-NDs. It seems that several others are recommending the Singh-Ray. I have the 82mm version and it's pretty good. I found that the 77mm low profile one still caused a vignette with some FF35 and wider focal length combos like the Nikon D3 with 17-35 zoom. So I sent it back and went with the 82mm. I have a super-low-profile step ring and it works great. The ND causes noticeable color tinting as block out more stops of light, it's not just potential IR pollution.

You also don't want to combine most IR filters with polarizers, especially dual polas in this case. I also subscribe to the practice of putting as little between my subject and lens as possible.

If you use SLR lenses, then definitely take a look at the Sing-Ray. But it's not a tool for every job. In most cases, if you need 4 stops of ND, you're best to just to put a single ND or IR+ND 1.2 filter in front of the lens. The vari-ND is really only useful, especially with its potential shortcomings and side-effects, if you need to be able to change on the fly while you're shooting. Like I said, you can also rig this up with a mattebox if you stack two c.polas and rotate one of those stages. I like the Tiffen water-white ones that claim to not introduce any color shift. They still do when you start blocking enough light, but they're better than most. And this is where most of the cheaper ones you can find for SLRs have trouble. Much more than 3 or 4 stops and you start getting a grey-blue, pink or purple tint with the cheaper filters... And it's not always IR pollution. FWIW, you can see the same thing when stacking multiple ND filters. I occasionally run across shots where people stacked NDs to get the right exposure and they're blaming the magenta or purple tint over the entire frame on IR pollution, when it's really their ND combination that creates the color cast. Overall color casts are relatively easy to correct out with white balance ant tint controls, but it can still affect your image quality as it restricts certain wavelengths from passing through -- often the green, which accounts for 50% of your resolving photosites on a Bayer pattern sensor.
 
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