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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 :)

Red and the infraRED

I want to order a Rosco 4x5.65 hot filter! How do I do this?
 
IR relief

IR relief

Finner, I just went to the Rosco site and searched for "hot mirror" and there it was. I sent them an email asking about purchase of 4" by 5.65" with smoothed edges for use in a mattebox. I also asked about quantity discounts and resale policies, don't expect to hear back until Monday. Considering that most of my Schneider filters were $300 and change, the $53 that Michael quoted sounds pretty darn good.
 
Blair, could you report back to us and let us know? It seems they could get something set up so we don't all have to describe the same thing to them.

And, okay, here goes...what's a "hot mirror"? I feel stupid. Is this filter made out of glass? What does a hot mirror do besides, obviously, cut IR? Is it made just to cut IR?
 
Actually, let me handle this one, if I may.

I'm already in touch with Joel Svendson at Rosco. We've already discussed a market for RED One users and building a filter that best suits a matte box. There is more for us to discuss and discover.

It helps that the manufacturing plant is only six miles from me and I have an open invitation to visit. ;-)

Rosco may not be able to deliver all the specs:
  • .15" thick like my Schneider ND's (although they can double the thickness of my version.)
  • flat and parallel (although it looks damned flat to me)
  • dressed edges and corners (although I could do that with a glass grinder over an afternoon)
Rosco can, however develop a dichroic formulation that cuts deeper into the infrared than this particular off-the-shelf filter. Joel is interested in investigating the market for such an effort. The RED One is noted as sensitive to 1200nm.

Once this is set up you can order filters via any local Rosco dealer. I ordered my custom cut from a local dealer and had it two days later.

Michael
 
Sounds like Michael is on top of this one! Just as additional background, the "hot mirror" or IR-cut filters are constructed by vacuum-deposition of many thin dielectric films of carefully controlled thickness. As he mentions, they can be "tuned" to the specific wavelengths you want to pass, and those you reflect back.

You can deposit these films on plain clear glass, and it sounds like that's the stock item that Michael got. In the visible region it will look clear, I think the light loss is less than 1/2 stop. You can also deposit them on ND filter glass, or many other types of glass, giving you the IR-cut property in addition to whatever filter type it was originally. I believe thin film deposition is done on some kinds of sunglasses, also :-).
 
jbeale said:
You can also deposit them on ND filter glass or many other types of glass. I believe thin film deposition is done on some kinds of sunglasses, also :-).
Click to expand...

I wonder if Rosco could do a ND hot mirror combo... like a 1.2 ND. That would be handy. I swear, there's a lot of little hatches to batten down on this camera - but I'm still glad I'm along for the ride. You shoot RED, you want to shoot it some more. It's like camera crack.
 
Illya Friedman said:
I certainly can't speak for Panavision, but as far as DALSA is concerned, we solved all previous minor issues relating to IR about 14-months ago.

I've attached a downconverted 2K image from a horror film that shot with the camera about a year ago now.

Illya Friedman
DALSA
Digital Cinema Division
www.dalsa.com/dc
Click to expand...

Congratulations on a film with your camera Illya is that horror film in the movies soon? Nice fire photo.

I have never heard of the Dalsa Cinema, What is the cost of your camera and does it record to compact flash in 4k as well or just 2k?
 
Just spoke to the head of Euro sales for Schneider yesterday, and he told me that they're looking to announce a solution (sounded like they'd be shipping straight away too, but may not be the case) at NAB.

By the sounds of things they're looking at producing a 1.5/1.8 ND and IR cut combo filter. Sounds good...
 
IR-gent

IR-gent

Michael - glad to let you take the lead with Rosco. Just let me know how it turns out.

Most of my current filter kit is Schneider, including 4" by 5.65" NDs in 1.8, 1.2, .9, .6, .3. While I like the idea of a 1.5 ND with IR cut I would also want one I can stack in front of my current NDs. Not real excited about replacing $1,500 worth of almost new filters :ohmy:
 
Sure thing - but if it's stackable anywhere in the filter path that'd be good, and it shouldn't require you shelving $1,500 worth of filters either, if you wanted to go that route - you'd be replacing your 1.8 with it, I'd imagine, and leaving the rest the same.

Unless they do a variable IR-cut filter combo with all of their ND strengths, of course...

For you though, sounds like the hotmirror may be the way forward - good to have options, as ever.
 
According to Joel Svendson, an IR filter solution for matte boxes is now officially a "project" at Rosco.

Rosco has another formulation that cuts IR to nearly 1200nm.

I'll be visiting the Austin plant on Friday to discuss further.

More later...

Michael
 
Just spoke to Steve at Abel... He says Tiffen is now selling IR ND filters in multiple sizes and strenghts.

I asked him if they were resin or glass, he will be getting back to me.
Cost seems to be about $255.00 per.

Jay

Can you stack IR filters? I would think you'd only want the outside filter to be IR.. Or am I off base here?
 
Jay A. Kelley said:
Can you stack IR filters? I would think you'd only want the outside filter to be IR.. Or am I off base here?
Click to expand...

A "hot mirror" filter does what it sounds like, it acts mostly like a mirror for the IR wavelengths. Normally you'd use only one, in front. If you stack them you'll end up with multiple reflections between the plates for any IR that does get through. Assuming the front mirror was mostly effective, that may not cause any visible problems- but probably have to try it to see.

It's always best to use the minimum filters possible, so if you need to cut 5 stops it's best to use a 1.5 ND instead of stacking a 0.9 and 0.6 for example.
 
Great thread BTW!

First I'll say that I'm (maybe unfairly) assuming that a lot of posts on this thread are from film shooters who've had the wonderful luxury of shooting using a, close to, panchromatic medium.

That said:

Infra-red has been a pain in the arse for us video shooters since the arrival of the CCD. I remember in the early 90's finding that remote control type IR LED's would show up (white/grey) on the image and that if one removed the IR filter one could film in the dark using IR lighting (giving cleaner results than using image intensifiers - though without their great sensitivity). IR was a much greater problem on the cheaper cameras than the more high end video cameras but I always had the impression that this was the price of increased sensitivity.

Anyway I've always found there to be a problem of IR (over)saturating the
detectors. Earlier someone mentioned tail lights on cars, yep they're a pain esp around twilight, lots of dusk's blue light - a common occurrence in the UK when overcast - combined with (from the camera POV) over saturated red light makes for horrible looking images. (commonly seen on UK news broadcasts as they often shoot around twilight to make the early evening news)

Shooting the sun at dawn or sundown can produce really odd effects depending on what the atmosphere is doing. (lots water vapour, dust or smog altering atmospheric IR transmission - or rather vis/IR ratio's - can really mess up an image) I've had to apply saturation/colour limiters a few times to make the image legal for broadcast!

Both red tail-lights and a red dawn/dusk sun could give an orange/yellow/white in camera (instead of red) and occasionally a kind of red coloured coma!

Again as already mentioned traditional lighting often gives out masses of IR but there is a new(ish) issue as new lighting technologies are becoming more common and that is that most fluorescent and LED lighting systems are by no means pure pan-chromatic sources (forgive me if I'm teaching you all to suck eggs here) rather they are a collection of narrowband sources that give the eye the impression of being white. Try looking at a white LED or a fluorescent tube through a prism, instead of a continuous spectrum you'll just see a collection of separate channels. Now the real B. here is that if the narrowband channels of the light source are a little off compared with the sensitivity of RGB channels of the camera this can throw off colour balances and in more serious examples (rare), exposure.

Anyway my point is that this issue has its work arounds (it just seems that we need a company to produce cine sized IR cut-off filters). And in ways through recording RAW files, some advantages, as Black and White filming can greatly benefit from a bit of IR sensitivity which can now be properly accessed for grading unlike previous generations of electronic camera formats.

And as always the rule seems to be TEST, TEST and TEST!!!

Oh! On electronic cameras the blue channel has always been the noisiest!

JohnF
 
Oh another observation.

The Lens one shoots with could also effect the amount of IR being picked up.
Some appeared to cut off whereas others would give the impression that they were increasing IR sensitivity. Or more likely focusing the IR wavelengths closer to the image plane giving the impression of greater sensitivity.

Any thoughts?

JohnF
 
5000K biased LEDs?

5000K biased LEDs?

Sounds like there is an opportunity out there for someone to market lights designed to work well with dCinema cameras.

Presumably we'll want LED based lighting for efficiency and to reduce bulk. The design criteria would need to include managing the narrowband output profile to match cameras like the RedOne, Viper, Genesis, etc.

Traditional lighting instruments for our work generally waste a great deal of energy as heat which causes further issues in terms of size, heat resistant gels, power consumption, etc.

Less heat, less energy consumption, ... :love:
 
Jay,

The Hotmirror will have to be the outward most filter. It will be clear once you start handling them that they reflect a lot of incident light visible light (light striking the filters from odd angles) . You don't want that light bouncing around hitting other filters.

Just look at all the magenta and cyan a hot mirror reflects if your not directly in front of it.
2143949762_69ba3db714.jpg


I can't imagine these filters not being glass. The process to create them involves evaporating a metal onto the surface of the filter. This takes high heat, and I doubt resin filters could ever hold up to it. Most other filters just involve a dye layer or gel sandwiched between layers of glass, it's very different than a hot mirror filter.
 
Michael Morlan, excellent test. Thanks...
Jay are they officially shipping those filters? I was sworn to secrecy by my filter guy that this was to be a big announcement by Tiffen at NAB, an IR filter tailored for Red. Cat's out of the bag already I guess.
Apparently they can be ordered in combination or "clear". I've already spent thousands on 1.2, 1.5, 1.8 NDs so I suppose I'll order the "clear" ones.
But if the Rosco solution performs well, that is quite a bargain at $54. Keep us informed Michael M.
Cheers,
Harry
 
Panchro mirrored ND's anyone?

It was mentioned at the beginning of this thread and is supposedly a solution.

Unfortunately I don't have my camera (although I just got the infamous e-mail) and need to order filters for an imminent shoot...

Someone...PLEASE...TEEEEEEEST! :ohmy:

Dylan Macleod
Cinematographer
Toronto, Canada
www.dylanmacleod.com
 
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