December 30, 2012

Choosing Neutral Density Filters with Infrared Protection: Necessary or Overboard?

At this point, solid state image sensors have matched or exceeded film in a lot of ways, including light sensitivity, responsiveness to shadow detail, and overall dynamic range -- but that doesn't mean our chips aren't susceptible to certain problems previously avoided by the nature of emulsion. Indeed, 'sensitivity' nowadays means something different altogether -- and with the virtual necessity of neutral density filters as a result, this often means vulnerability to infrared pollution. Unless you like shooting at f/22 or you're already using the Aaton Penelope Delta, you may also require an IR filter with your ND. AbelCine has recently shared a great rundown of which cameras suffer the most from IR pollution -- and what filters work best to correct each.

Here's the short version of AbelCine's IR filters expo, followed by the full length presentation if you want to check out the whole thing.

Below is a price breakdown listing the filters used in the video -- there are many size variants for each, which I've tried to include because some DSLR-shooting readers may prefer the on-lens options over the rectangular matte box solutions (where applicable).

I for one was happy to see how well balanced the BMCC performed even sans-protection -- and even more surprising was how well the Canon C500 shot through straight ND. There's no doubt IR filtration will improve your footage out of the gate, as demonstrated in a post by Crunch Motion Design GMBH with the RED MX sensor -- the left grab uses ND 1.5, the middle uses an ND 1.5 Rosco IR filter combination, and the right: ND 1.5 with Schneider IR filtration added. The top triptych is ungraded RAW, while the second (with the same filter arrangements) is corrected in REDCINE:

On the other hand, the same post asks if IR filtration is truly a necessity with the use of ND, having found unfiltered RAW images could be mostly 'recovered' and adjusted in post -- check out the full post for the rest of the findings.

Whether or not you need IR filtration may be as much about your own preference and tastes as it is about your budget and gear -- some cameras will hold up better to post correction of IR pollution than others, so you'll have to use your own judgment depending on what you're using. Many will surely prefer to save the money and just 'live with it,' while others simply won't allow for that upper-red radiation to seep into their image. There's plenty of other IR-centric test and testimonial material out there, so feel free to share any that may have been eye-opening or useful to you -- plus any of your own experience with IR pollution you may have had.

Links:

Your Comment

12 Comments

Thank you. This first video is excellent and explains a lot of things for me,

December 30, 2012

1
Reply

Why surprised about the Canons? The C100/300/500 all have a hot mirror-style IR filter built in between the lens mount and the ND filters, and it serves to seal all that works so your NDs and sensor don't get dirty. No need to worry about this or a lot of other things it all just works.

The Canons are very well designed and implemented. I get a kick out of people who hate on them. But at least we're all not shooting on the same camera.

December 30, 2012

0
Reply
Peter

I was thrilled to see Canon clearly has decided to fix this "in-camera", which is always preferable to fixing it in post. Since C300 and C100 have an identical codec as C500, these are truly good working tools.

December 31, 2012

1
Reply

Filters are a good thing. Protect your glass, protect you ass.

December 31, 2012

0
Reply
ThunderBolt

Wow!!!!!.......... After 4 freaking months not knowing what the hell was happening to the movie I'm editing. Finally the best answer.

THANKS SO MUCH!!!!!!!!!!
5 stars to Abelcine and NFS!!

December 31, 2012

2
Reply
Kay

don't panic people :)

December 31, 2012

0
Reply
hansd

I believe the 5diii has a built in IR filter. I wonder if it's the same as the ones on the cinema cameras. Just starting to shop for filters for my Tamron 24-70 and was considering the need for IR on the NDs.

December 31, 2012

-1
Reply

So far, I've had no problem with this issue. It's nice to see people considering it, but I don't think I'm going to spend a lot of my time worrying about infrared light.

December 31, 2012

1
Reply
DIYFilmSchool.net

IR is definitely a problem area. I first encountered it with the Sony F-35 with 12 stops ND in front of the lens. This was before IR filters were standard filters as they are now. The leaves on the trees went brown. The only fix was to use the built in ND wheel on the Sony, just like the old time video cameras had and some new cameras still have. The internal ND wheel also blocked the IR. Worth a try if you have that style camera. I also ran into this on some accidentally underexposed Canon 7D footage. It can't be fixed in color correction, just manipulated a bit.
So, great, informative video. IR will surprise you if your don't prepare for it. Thanks!
Best to you and to all on your projects.

January 2, 2013

0
Reply

Do you seriously like the BMCC sans protection? (I'm honstly asking, not being disrespectful.) Check out 2:45 of the first video - the blacks are bright purple. According to Micth the BMCC needs IR potection almost straight out of the gate. (With low levels of IR.) If this is an effect you like, or don't mind that is one thing. Accurate and precise colors are a different issue.

Even with RAW images IR is still a problem if your goal is accurate colors and skin tones at the end of the process. I have 5k RAW files available for download here if you want to play with them for yourself: http://www.ryanewalters.com/Blog/blog.php?id=4094508292434585142

The problem these days, and demonstrated well in the video examples, is that different cameras need different solutions. If you only use one system, then only one solution is needed. I use multiple systems, so I'm looking into solutions that work a cross multiple camera systems ... Lots to figure out on this end, and there doesn't seem to be any one answer for everything unfortunately ...

January 3, 2013

3
Reply

I use an IR/ND filter on my EX3. Without it on hot days, skin tones have a funky fake looking tan. Other things started to turn organe. I'd hate to fix that pollution in post so I opt for the quick camera fix...even if I lose a stop.

January 7, 2013

0
Reply
Shawn

Digital has by no means exceeded film in shadow detail nor overall dynamic range. It may be very close in matching the quality but if we are to teach others about digital we shouldn't be teaching them to think that film is out of the picture. It is a viable and extremely high quality means to capture an image. If you're a DP, a director may still ask to shoot on film. Be ready and study the original formats that digital has been trying very hard to match all these years and still does.

July 5, 2013

0
Reply
Andy