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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. . .

Hans von Sonntag said:
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.
Click to expand...

I think the hot mirror downsides are as follows:

It's another piece of glass. Every filter costs a bit of contrast and resolution and could be the cause of unwanted light hits and reflections.

Takes up matte box real estate, it should be in the front of your filter stack.

Loose a bit of stop, maybe a 1/3rd

Slight warm color shift.

Not so bad... I don't think I'll use it as a default, but will use it outside whenever using ND .9 or more and under 3200k situations where I'm using large units close to subject. Also hot environments, the engine room of a ship, a sauna, the Red booth at NAB.

Matt Uhry
www.mattuhry.com
 
Ah, I didn't know that 1/3 of a stop will be lost, interesting.

Yes I thought that 3200K is more prone to IR than a dylightlight situation. Interesting that physically "hot" places are prone to IR. Does make sense though.

Obviously I'm new to this issue, never came across this until yesterday when I saw on a shoot with the RED magentaish blacks on a photo we had in the background.

Thanks for doing my homeworks:)

Hans
 
I have to disagree about the stop loss. All my 486 filters have no light loss at all. They are considered to have a filter factor of 1 (which at it's worst is 95% light transmission) http://en.wikipedia.org/wiki/Filter_factor

Any visible light loss through the RED is due to the fact that IR is added to RED's visible light exposure. So by cutting out the IR it might appear darker on some materials (Matt's shirt in his video posted earlier in this thread)

Hans I think he's joking about the physically hot areas.
 
I am a little confused...is there a specific order in which the filters need to be used? What I mean is do I need to put the IR filter first (forefront of the matte box) and then the ND? (second slof of the matte box closer to the lens) or can I use an ND in the mattebox and possibly then use a screw on IR filter on the lens...does the order of the filters make a difference?
 
3xm said:
..does the order of the filters make a difference?
Click to expand...

Yes, the IR cut filter or "hot mirror" reflects the IR light back like a mirror. If it's behind other glass it could start bouncing around wildly so you want your IR filter up front. Usually you want ND first, Color second, Diffusion last in your MB.

I think a Red filter package should include:
-Clear IR filter
-ND.3
-ND.6
-ND.9IR
-ND1.2IR
-ND1.5IR
-80C
-Circular Polarizer
-ND Grads
-Diffusion set of your choice
 
florianstadler.com said:
Yes, the IR cut filter or "hot mirror" reflects the IR light back like a mirror. If it's behind other glass it could start bouncing around wildly so you want your IR filter up front. Usually you want ND first, Color second, Diffusion last in your MB.

I think a Red filter package should include:
-Clear IR filter
-ND.3
-ND.6
-ND.9IR
-ND1.2IR
-ND1.5IR
-80C
-Circular Polarizer
-ND Grads
-Diffusion set of your choice
Click to expand...

Which in this case meant no screw on IR filter. It seems the IR filter has to become a permanent filter for the MB, if Tiffen releases one during this NAB, until this issue is resolved. Or am I wrong with these assumptions?
 
twlim said:
Which in this case meant no screw on IR filter. It seems the IR filter has to become a permanent filter for the MB, if Tiffen releases one during this NAB, until this issue is resolved. Or am I wrong with these assumptions?
Click to expand...

Yeah, you can't screw on an IR and then put other filters in front of that.

But the The NDIR is a combined ND and IR filter. So that could be screwed on if it was your only filter. If you had a screw on polarizer you could screw that on first. I'd probably use bigger filters and a stepup ring at that point to avoid problems with vignetting on wider lenses.
 
I talked to one of my DPs about this today. Tiffen now has IR NDs available in .3, .6, .9, 1.2, 1.5, 1.8 and 2.1 in 4 x 5.65. Apparently Schneider's process results in too many layers to be practical at this time.

Based on an ASA of 320 and T 1.9 Ultra Primes for exterior shooting, I plan to use a 1.2 IRND as the first filter to cut the IR, then if needed, "tweak" with standard NDs or when needed, or a 138 round, 1 stop pola in cases when I need polarization. This should put me in the right ballpark in terms of stop and depth of field.

Since the issue seems to be related to the excessive IR RELATIVE to full spectrum light level, I don't feel like I need a bunch IR filters. Just the primary, "most likely to use" IR ND to tame the IR component.

Anyone have a thought on this? Make sense?

M
 
Mark Pedersen said:
I talked to one of my DPs about this today. Tiffen now has IR NDs available in .3, .6, .9, 1.2, 1.5, 1.8 and 2.1 in 4 x 5.65. Apparently Schneider's process results in too many layers to be practical at this time.

Based on an ASA of 320 and T 1.9 Ultra Primes for exterior shooting, I plan to use a 1.2 IRND as the first filter to cut the IR, then if needed, "tweak" with standard NDs or when needed, or a 138 round, 1 stop pola in cases when I need polarization. This should put me in the right ballpark in terms of stop and depth of field.

Since the issue seems to be related to the excessive IR RELATIVE to full spectrum light level, I don't feel like I need a bunch IR filters. Just the primary, "most likely to use" IR ND to tame the IR component.

Anyone have a thought on this? Make sense?

M
Click to expand...

What about the Panchro mirrored ND's? They are supposed to cut IR as well no?

I hope so...I just ordered a set!:sarcasm:

Dylan Macleod
Cinematographer
Toronto, Canada
www.dylanmacleod.com
 
Mark Pedersen said:
Since the issue seems to be related to the excessive IR RELATIVE to full spectrum light level, I don't feel like I need a bunch IR filters. Just the primary, "most likely to use" IR ND to tame the IR component.
Click to expand...

In theory, an .3NDIR and a 1.2NDIR should have the same hot mirror
performance so if already had an ND set, adding a .3NDIR seems to make sense. You'd only need to start with the .3NDIR when building up higher ND
using normal NDs for the rest.
 
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