Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

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Rolfe Klement

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Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostWed Jun 06, 2018 12:39 pm

I know this has been done to death but I bought the Firecrest Ultras - and it turns out they are not IR cut filters. :-( They are amazing but not IR Cut.

I basically need Skin to look good (number 1 priority) and to get rid of that Purple haze and those weak blacks.

I have heard Hot mirrors screw up skin tones
I have heard NiSi IRND are good but quality varies
What about Whitewater or GlassPro by Tiffen
Also the Schnieder
Any others?
etc

I also want the lowest ND cause I often shoot in low(ish) light

thanks
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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostWed Jun 06, 2018 1:50 pm

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JacobSchuhle

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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostWed Jun 06, 2018 2:33 pm

Rolfe Klement wrote:I know this has been done to death but I bought the Firecrest Ultras - and it turns out they are not IR cut filters. :-( They are amazing but not IR Cut.

I basically need Skin to look good (number 1 priority) and to get rid of that Purple haze and those weak blacks.

I have heard Hot mirrors screw up skin tones
I have heard NiSi IRND are good but quality varies
What about Whitewater or GlassPro by Tiffen
Also the Schnieder
Any others?
etc

I also want the lowest ND cause I often shoot in low(ish) light




thanks


You shouldn’t need an ir cut without using an nd right? So low light shouldn’t matter
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Denny Smith

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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostWed Jun 06, 2018 4:25 pm

Depends on the light source...
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Robert Niessner

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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostWed Jun 06, 2018 7:11 pm

I have the Schneider True Cut 680 4x5.65 and I am happy with the results.
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Jamie LeJeune

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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostWed Jun 06, 2018 11:47 pm

Perhaps it’s been posted elsewhere already on the forum, and please forgive my question if it has, but I’d love to know how BMD chose the level of IR filtering (or not) in their sensor design. All the BMD cameras so far have been relatively sensitive to IR, or so it seems to my eyes when grading, more so than the Canon, Sony and Panasonic cameras I’ve used. Also, I’ve never seen an aftermarket internal IR insert for those brands as can be found for the BMCC and BMPCC (and one was proposed for the Ursa Mini 4.6K, but I haven’t seen it actually released).

Anyone have any info about why BMD allows so much of the IR spectrum into the signal?
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thomas bruegger

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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostThu Jun 07, 2018 9:02 am

BM should sell a set of ND-IR Filters for the Ursa-Mini equal to the ones they use internally in the UM-Pro they work great!
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TeryWilson

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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostSun Sep 30, 2018 3:36 am

Robert Niessner wrote:I have the Schneider True Cut 680 4x5.65 and I am happy with the results.


do you use this filter along with your ND filters? I'm looking for a 2 stage mattebox now so that I can use these filters. I came across this one, is it good? https://www.bhphotovideo.com/c/product/944000-REG/schneider_68_121244_4x4_true_cut_715_ir.html
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rick.lang

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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostSun Sep 30, 2018 4:02 am

Tery, that’s the filter I use with my Misfit Atom matte box. Just used it on the wedding last Saturday and no hint of a problem. It doesn’t cut until 715nm rather than the 680nm in wide use. The argument is that it will produce better skin tones. Of course there are many factors in getting good skin tones but capturing some of the deeper red is important in my opinion.


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TeryWilson

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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostSun Sep 30, 2018 5:41 am

rick.lang wrote:Tery, that’s the filter I use with my Misfit Atom matte box. Just used it on the wedding last Saturday and no hint of a problem. It doesn’t cut until 715nm rather than the 680nm in wide use. The argument is that it will produce better skin tones. Of course there are many factors in getting good skin tones but capturing some of the deeper red is important in my opinion.


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Thanks Rick. I'm still learning, "self taught cinematographer", can you explain what you meant by, "It doesn’t cut until 715nm rather than the 680nm in wide use."? I never heard of "IR Cut" until I started looking at the 4.6k that I just purchased.
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rick.lang

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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostSun Sep 30, 2018 6:32 am

Where to begin? The colour of the electromagnetic spectrum can be associated with the wavelengths of light they have. These wavelengths are commonly measured in nanometers (a billionth of a meter). Where a visible colour begins and ends is approximate. But somewhere around 600 nanometers, red moves in deeper shades (deep red or far red) and eventually the wavelengths become invisible to our eyes as the longer wavelengths become infrared light (heat). However some emulsion films and modern sensors are more sensitive to infrared compared to our vision as the photosites still react to those infrared wavelengths.

When our eyes see a black nylon bag, the digital sensor may see a reddish bag; when our eyes see green leaves, the digital sensor sees a muddy leaf. These are examples of infrared pollution and there are two or three methods of filters that solve this pollution problem. There are hot mirrors and IR Cut filters that either reflect or absorb the infrared radiation and there are filters that attenuate (reduce but not eliminate infrared rays. Often attenuation is sufficient and many IRND filters are this type of filter; they are becoming increasingly popular as one filter might take care of both infrared and reduce the intensity of visible light. But the most common filters are the IR Cut filters.

Now these Cut filters aren’t like a pair of scissors cutting a piece of paper. They reduce the longer wavelengths gradually, beginning to be effective around 650, 680, 700, 715, 750 nanometers (nm) depending upon their design. 680 is the norm that effectively eliminates infrared pollution—that’s the goal and a good thing, right?

The answer isn’t a yes or no but a maybe. Because fixing a nylon bag or a rayon shirt is one thing, but getting the best skin tones is another. Skin isn’t a homogeneous colour. It’s a lot of colour even when the overall time may be ‘brown’ or ‘black’ or ‘yellow’ and so on. Skin contains some degree of red and dark red and if you cut infrared too soon, you may be reducing some of the deep red that may appear to be imperceptible but may actually aid us in identifying good skin tones. So even though Schneider makes stronger infrared Cut filters they also make filters that cut about 715 or 750nm.

So I chose 715nm for my matte box filter. I also have a 680nm filter for a screw-on filter and I use SLR Magic Image Enhancer Pro filters that attenuate infrared through a much longer band of wavelengths, say 1200nm.

You just make your own choice. I’ve tested the three alternatives and seen differences so you begin to learn what a given scene calls for. Once in awhile, you make the wrong choice, but generally you adapt to whatever you choose.

Hope that makes sense. The book with all the details won’t be available from Amazon this winter, but I trust you’ll manage.


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TeryWilson

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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostSun Sep 30, 2018 6:46 am

Oh wow Rick thanks for taking me to school!!!!! Love the details and greatly appreciate you taking the time out to help me understand this better.

Having said that, would you recommend an IR cut filter over IRND filters? Now you bout to have me researching IRND filters lol. I just purchased my matte box so now I'm looking for afforadable 4x4 filters n didnt know that now I can get and IR cut and ND filter in one.
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Mattias Kristiansson

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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostSun Sep 30, 2018 10:56 am

TeryWilson: Well... An IRND filter isn't really an IR filter combined with an ND filter although it may sound like it.

An IR filter blocks IR almost totally.

A regular ND filter usually block visible light but not IR, and thus shift the balance between IR and visible light in an unfavorable way, thereby making IR contamination very obvious.

An IRND filter usually block IR and visible light to the same extent. That means that it won't create an IR problem, but if you have visible IR contamination to begin with it won't take care of it either.

So, even if you get a set of IRND filters, you should also get an IR filter for dealing with difficult situations, especially scenes heavily lit by tungsten.
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rick.lang

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Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostSun Sep 30, 2018 12:24 pm

Good advice from Mattias. There are many situations where an IR Cut is required, but IR does not affect every situation. Especially when you shoot with very low strength ND or no ND filters. So on a heavily overcast day at the beach you may not see any infrared contamination. And if your subjects are nude, they may not exhibit any IR pollution, but if they’re wearing clothes or carrying a bag, some materials may be more susceptible to IR pollution. Having the IR Cut on the camera at all times is playing it safe, but it’s another layer of glass and good if you know you don’t need it.

All my ND filters are good quality IRND filters. I use complete sets of 8 rectangular 4mm filters from NiSi for the matte box and 10 screw-on filters from SLR Magic. These are very good budget filters. Not perfect, but not a challenge in post to correct any variance. If you win a lottery, buy some Lee filters or Panavision. Most people here use other quality brands with success.

For the wedding I just shot, I only used the Schneider True-Cut 715 and there was not a single problem with IR pollution. I shot INT DAY and NIGHT all lit with tungsten and daylight. There was lightly overcast EXT DAY from about 4:30 pm on the URSA Mini 4.6K. It was a twelve hour day with a good break for me between prepping the bridal party and the wedding.

I had no chance to test the wedding clothes, but thankfully no IR pollution or moiré either.

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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostTue Sep 27, 2022 3:46 pm

rick.lang wrote:Good advice from Mattias. There are many situations where an IR Cut is required, but IR does not affect every situation. Especially when you shoot with very low strength ND or no ND filters. So on a heavily overcast day at the beach you may not see any infrared contamination. And if your subjects are nude, they may not exhibit any IR pollution, but if they’re wearing clothes or carrying a bag, some materials may be more susceptible to IR pollution. Having the IR Cut on the camera at all times is playing it safe, but it’s another layer of glass and good if you know you don’t need it.

All my ND filters are good quality IRND filters. I use complete sets of 8 rectangular 4mm filters from NiSi for the matte box and 10 screw-on filters from SLR Magic. These are very good budget filters. Not perfect, but not a challenge in post to correct any variance. If you win a lottery, buy some Lee filters or Panavision. Most people here use other quality brands with success.

For the wedding I just shot, I only used the Schneider True-Cut 715 and there was not a single problem with IR pollution. I shot INT DAY and NIGHT all lit with tungsten and daylight. There was lightly overcast EXT DAY from about 4:30 pm on the URSA Mini 4.6K. It was a twelve hour day with a good break for me between prepping the bridal party and the wedding.

I had no chance to test the wedding clothes, but thankfully no IR pollution or moiré either.

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Rick, in your opinion, The True Cut 715 is the go to cut filter? I have a Pocket 6k. I currently own a BW 486 MRC. I want to get a larger 4 x 5.65 IR Cut filter.
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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostTue Sep 27, 2022 4:26 pm

I went a different route. Nearly all my use of the camera is outdoors. I cut a circular piece of sample resin IRND filter by Formatt Hitech. The company had the good grace to send some samples to me to experiment with back in the days of the SI2K.

My objective was to reduce the effective ISO of the camera to enable sensible lens aperture settings with sensible shutter speeds in Australian bright outdoors environments and avoid extra attachments to the camera when possible.

I attached the disk of IRND filter on the rear face of the antireflection cone found in the throat of the camera. To protect the filter material from chemical attack, I used mere pinpoints of instant glue to attach the filter disk to the antireflection cone.

When the cone is screwed back into the camera throat, care needs to be taken not to bottom the filter face against the inbuilt IR filter or both may be scratched or the inbuilt IR filter cracked. If the IRND filter disk is carefully cut and dressed to size, it will bottom onto the neoprene ring which retains the inbuilt IR filter.

The thickness of the filter disk requires that the lens mount be shimmed forward to compensate. If you are using autofocus lenses, then the little pin block has to be also shimmed forward or pin contact may not be complete.

The most convenient method of shimming the mount forward is to cut ring shims to stack in a circular groove in the front of the camera body. Plastic shim material is recommended as cutting the very narrow shims in brass is near impossible to achieve by hand.

This of course spoils the camera for use in low light environments unless the cone and shims are removed.
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rick.lang

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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostTue Sep 27, 2022 8:21 pm

ShaheedMalik wrote:Rick, in your opinion, The True Cut 715 is the go to cut filter? I have a Pocket 6k. I currently own a BW 486 MRC. I want to get a larger 4 x 5.65 IR Cut filter.


In my opinion, and I’m always on a limited budget so there may be a better solution if your budget is limitless, the True Cut 715 is a good choice. It lives in my Misfit Matte box. I’ve also used the 86mm B+W 486 MRC when I want a screw-on solution.

There may be debate about which strength is best as a 700nm and 750nm were also available but I took the conservative option believing anything stronger is too aggressive. I understand most seem to shoot somewhere around 680nm but that is clearly visible deep red, not near infrared. Even selecting 700nm is better than 680nm.

I know, I may be burned at the stake for saying that. Out of respect for the dead though, if you’re recording me being burned at the stake, please don’t use a 680nm filter!
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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostTue Sep 27, 2022 8:47 pm

rick.lang wrote:I know, I may be burned at the stake for saying that. Out of respect for the dead though, if you’re recording me being burned at the stake, please don’t use a 680nm filter!


:lol: :lol: :lol: :lol: :lol:
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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostTue Sep 27, 2022 10:06 pm

rick.lang wrote:
ShaheedMalik wrote:Rick, in your opinion, The True Cut 715 is the go to cut filter? I have a Pocket 6k. I currently own a BW 486 MRC. I want to get a larger 4 x 5.65 IR Cut filter.


In my opinion, and I’m always on a limited budget so there may be a better solution if your budget is limitless, the True Cut 715 is a good choice. It lives in my Misfit Matte box. I’ve also used the 86mm B+W 486 MRC when I want a screw-on solution.

There may be debate about which strength is best as a 700nm and 750nm were also available but I took the conservative option believing anything stronger is too aggressive. I understand most seem to shoot somewhere around 680nm but that is clearly visible deep red, not near infrared. Even selecting 700nm is better than 680nm.

I know, I may be burned at the stake for saying that. Out of respect for the dead though, if you’re recording me being burned at the stake, please don’t use a 680nm filter!


Where are you finding the True Cut 700 in 4x5.65?
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rick.lang

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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostFri Sep 30, 2022 4:17 am

ShaheedMalik wrote:
rick.lang wrote:
ShaheedMalik wrote:Rick, in your opinion, The True Cut 715 is the go to cut filter? I have a Pocket 6k. I currently own a BW 486 MRC. I want to get a larger 4 x 5.65 IR Cut filter.


In my opinion, and I’m always on a limited budget so there may be a better solution if your budget is limitless, the True Cut 715 is a good choice. It lives in my Misfit Matte box. I’ve also used the 86mm B+W 486 MRC when I want a screw-on solution.

There may be debate about which strength is best as a 700nm and 750nm were also available but I took the conservative option believing anything stronger is too aggressive. I understand most seem to shoot somewhere around 680nm but that is clearly visible deep red, not near infrared. Even selecting 700nm is better than 680nm.

I know, I may be burned at the stake for saying that. Out of respect for the dead though, if you’re recording me being burned at the stake, please don’t use a 680nm filter!


Where are you finding the True Cut 700 in 4x5.65?
I haven’t looked recently so the rectangle might no longer be produced; the 715 I bought years ago was a 4”x4” square. I hope my recollection of the existence of the 715 4”x5.65” is accurate.
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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostFri Sep 30, 2022 5:23 am

I only use nisi filters and am quite happy with them. I have the irnd 4x5.65 cinema line as well as the screw on filters. In addition I have some irnd gnd soft grad filters and like them very much, too.
Quality is top notch and nothing to complain about and I can see no variations in quality so far.
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rick.lang

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Re: Best IR Cut filter (4 x 5.65) for Ursa 4.6k (not Pro)

PostFri Sep 30, 2022 3:45 pm

Agree the NiSi 4x5.65” IRND are good value. But in my testing a few years ago, I found there may be conditions for which an actual IR Cut is required, particularly with some materials such as nylon that are more susceptible to showing infrared pollution. I always shoot with the 715 IR Cut in my matte box just to be safe.
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