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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 ND filter issues. . .

I'm a little confused about this issue..

Can this IR pollution be solved with a simple color correct?
 
rgdfilmsRED said:
I'm a little confused about this issue..

Can this IR pollution be solved with a simple color correct?
Click to expand...

No it's ugly and nasty. IR focuses differently than visible light with most lenses so it looks out of focus and hazy. Messes with your color rendition, but differently on different colors. Hard to near impossible to correct.

Don't freak out, the situations where you have a serious IR pollution problem are predictable and not too frequent. It's also a nice magic trick when you deploy the hot mirror, and it instantly cures your IR ills.

Do your own test.

Matt Uhry
www.mattuhry.com
 
looking for clarification:

option one: use existing ND filters but add hot mirror (when available) in front of NDs. this because typical cinema NDs block visible light, but not IR.

option two: if you do not currently own NDs, hold off buying them for a few weeks if possible as Tiffen (and soon Schneider) will be offereing NDs with IR blocking built into them. This will be cheaper than the hot mirror and let you use one less piece of glass in front of your lens.

option three: for those considering still lenses (with nikon mount, canon mount, etc.), you're sort of in luck already as NDs with IR cut cabability are already on the market for still lenses, as are hot mirror filters. the combinatoin NDIR filters aren't even particularly expensive.

in all cases, you can shoot now, lots of good shots are being had all over the world! BUT, study up on the situations where IR is a big deal and try to avoid those situations until better IR cutting options are available--and that's pretty soon.

for you guys that know your stuff, does this sound correct?
 
paul engstrom said:
looking for clarification:

option one: use existing ND filters but add hot mirror (when available) in front of NDs. this because typical cinema NDs block visible light, but not IR.

option two: if you do not currently own NDs, hold off buying them for a few weeks if possible as Tiffen (and soon Schneider) will be offereing NDs with IR blocking built into them. This will be cheaper than the hot mirror and let you use one less piece of glass in front of your lens.

option three: for those considering still lenses (with nikon mount, canon mount, etc.), you're sort of in luck already as NDs with IR cut cabability are already on the market for still lenses, as are hot mirror filters. the combinatoin NDIR filters aren't even particularly expensive.

in all cases, you can shoot now, lots of good shots are being had all over the world! BUT, study up on the situations where IR is a big deal and try to avoid those situations until better IR cutting options are available--and that's pretty soon.

for you guys that know your stuff, does this sound correct?
Click to expand...

About opinion three:

Of course for still lenses you can have IR filters right now.

Also for cine lenses I'm not so sure very soon.

It is very expensive to produce and the price would be like the highest for any type of filters.

But I'm asking myself

WHAT THE RED TEAM DID ABOUT THE IR ISSUE?

Dalsa said that (Illya Friedman's quote below):

"...but as far as DALSA is concerned, we solved all previous minor issues relating to IR about 14-months ago."

LINK>>>

Also waiting for Build 16 to see what happened about that.
 
Has anyone tested DALSA to see if they have an IR issue? I would not believe a sales guy unless it was tested by myself or someone I knew or respected.

I believe the RED team already stated they have put in the best IR filter that met the design tolerances. I haven't found IR to be a problem for me but just in case I'll get ND's with IR coating.
 
Fella's,

I'd love to see some examples of the pollution.
Can someone post some examples so if/when I see it I know what I'm looking at?

Thanks for the advice.
 
Bryan Fowler said:
I'd love to see some examples of the pollution.
Can someone post some examples so if/when I see it I know what I'm looking at?
Click to expand...


I've only had this problem when stacking 3 ND filters on top of eachother in a pinch. When using a single ND of any kind, I have had no issues.

I used this "problem" once for a shot just to get a certain look. An example of this shot can be found at the very bottom of this page:

http://www.zf-films.com/redframes
 
zak forrest said:
I've only had this problem when stacking 3 ND filters on top of eachother in a pinch. When using a single ND of any kind, I have had no issues.

I used this "problem" once for a shot just to get a certain look. An example of this shot can be found at the very bottom of this page:

http://www.zf-films.com/redframes
Click to expand...


That's cool.

Seems to me that many peeps are advocating that the Hot Mirror be put in irrespective of where you are or what you are shooting - which implies no downside. Are there any disadvantages to using this type of filtration all the time?

I do understand that there are only some situations where there's lots of IR flying around, and that the problem only really manifests itself when ND cuts the visible spectrum thus messing with the ratio of IR/other light. But is it better to be safe than sorry?
 
the ND's were the Tiffen IR/ND's and the hot mirror is a Tiffen. It was the biggest one they have ( 82mm screw in )

They are making larger hot mirrors ( will be at NAB ) and are looking into making combo Hot Mirror ND's

Matt Uhry
www.mattuhry.com
 
If you need to stack ND's won't multiple IR/ND's be a problem? Also if red fixes this problem with an IR hot mirror at the sensor similair to what dalsa does wouldn't the IR/ND's become a problem then.

Filters are fairly expensive and I hope to be able to rent them for many years. I would think standard ND's with a seperate hot mirror filter would be a better choice. I'm just thinking out loud with all this so hopefully some others can weigh in with their thoughts.
 
Finner said:
If you need to stack ND's won't multiple IR/ND's be a problem? Also if red fixes this problem with an IR hot mirror at the sensor similair to what dalsa does wouldn't the IR/ND's become a problem then.
Click to expand...

RED already has an OLPF with IR hot mirror on it. I have not heard anyone actually testing the dalsa camera for IR so there's no way to know how it compares. My guess is that it's the same.
 
Finner said:
If you need to stack ND's won't multiple IR/ND's be a problem? Also if red fixes this problem with an IR hot mirror at the sensor similair to what dalsa does wouldn't the IR/ND's become a problem then.

Filters are fairly expensive and I hope to be able to rent them for many years. I would think standard ND's with a seperate hot mirror filter would be a better choice. I'm just thinking out loud with all this so hopefully some others can weigh in with their thoughts.
Click to expand...

Finner's nailed it....

Matt Uhry
www.mattuhry.com
 
I know I was snuffed at for criticizing this test:

http://www.reduser.net/forum/showthread.php?t=7593

as being done very inconsistently. Different filters used equals test is not valid. Now we know why a Zeiss Masterprime, the sharpest piece of glass known to man could look so flat contrast and color wise and so soft.

This is a problem and the fix is hopefully on the way via an IR/ND filter set.

On the good note this can be a "look" that you can now exploit creatively. For example, you could tell your leading lady that you are polluting the image with Infra Red light to make her look even more stunning than she is in real life... :biggrin:
 
reality said:
RED already has an OLPF with IR hot mirror on it. I have not heard anyone actually testing the dalsa camera for IR so there's no way to know how it compares. My guess is that it's the same.
Click to expand...

Your guess would be wrong. I know A DP that has done IR tests with the Dalsa and the camera does very well, much better then the red.

Problem is red underestimated how much IR protection the camera needed. Red does well in fixing problems though. I am sure red will probably fix this mistake and a properly IR protected sensor may be one of the first cameras upgradeable options. Also the new IR protection probably will start to surface on cameras at some point soon.
 
I haven't thought about is thoroughly yet, but:

1. I like to have a single IR mirror 4x5.6

2. I like to have a ND9 combined with an IR mirror 4x5.6

All else combinations seem to work in a stack sufficiently.

I'm not sure where the downsides are when using a IR mirror. Any ideas?

Hans

PS: One thing is clear: RED is prone to IR pollution, this is a serious issue. Thanks to everyone for bringing this up.
 
I might be missing something here, but hot and cold mirrors are optical devices that are mounted at a forty five degree angle in the light path.
 
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