How properly stack Vari ND / IR Cut with Ursa Mini 4.6k

Hey there,

What is the best way to use a vari-nd and and IR cut filter with the Ursa mini systems?

I know that stacking filters is not generally advised.
and with vari-ND filters usually being circular I am a bit confused as the best way to achieve optimum results (within a modest budget of course).

I have a nice Vocas mattebox and will be cine-mod-ing my Leica R zooms to have 80mm OD fronts.

Would it be best to put the circular Vari-ND on the front of the lens and a 4x4 IR cut in the matte box?
Or would it be better to get a 4x4 to Circular filter adapter to use in the matte box with an IR cut?
Or is there another way?

Also any thoughts on using an IR cut all the time or just in conjunction with a vari-nd?

Thanks in advance for helping me with this n00b question.

Cheers

I put the UVIR as the first filter, then the ND, then the lens.


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Thanks Rick,
Any recommendations on decent 4x4 IR cut filters?
Any experience with the Skier brand?
I am having a hard time finding them in 4x4...

And while I have you I have a Tiffen VariND already from my last set up.
Do you have any preferences (again within reason)

thanks!

Thanks Rick,
Any recommendations on decent 4x4 IR cut filters?
Any experience with the Skier brand?
I am having a hard time finding them in 4x4...

And while I have you I have a Tiffen VariND already from my last set up.
Do you have any preferences (again within reason)

thanks!

I use a Hoya NDX Variable Density 3-400 and its work fine. You can find here https://forum.blackmagicdesign.com/viewtopic.php?f=2&t=49660 some answer at your problems. I hope help you this.

Thanks Rick,
And while I have you I have a Tiffen VariND already from my last set up.
Do you have any preferences (again within reason)

I've personally not gotten good results from Tiffen VariND on BMD cameras. The SLR Magic VariND has worked well for me when paired with Hoya IR cut filter. I seen others here on the forum also report good results from Heliopan VariND.

Shawn, I have a Schneider True-Cut 715 4x4" 4mm IR Cut filter. And a B+W 486M MRC 86mm screw-on filter. The current version of the 486 is a reasonably gentle sloping curve as it cuts infrared. It's very hard finding 86mm IR Cut filters so I went with this. The True-Cut 715 allows more deep red to pass up to 715nm before it cuts near infrared. Most IR Cut filters cut at about 680nm which is deep red.


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Shawn, as previously mentioned, I have the SLR Magic Vari-ND Mark II 82mm. The B+W 86mm IR Cut screws into that. No danger of vignetting with at combination. The Mark II includes the ability to set the degree of polarization you want before you dial in the ND strength you need. Innovative. Several people recommended it to me including Vic Harris and I like it. At maximum ND (6 stops) it has a slight yellow cast, but I happen to like that anyway. It only goes to six stops filtration to avoid the dreaded X-factor that ruins many shots that have stronger ND. So far I've survived with the six stops, but I haven't had the camera in blinding white snow at noon (or on South Beach, sadly) where you will need more than 6 stops.


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Rick, OK 2 follow up questions.

1. I am still catching up with the "science" of IR pollution... are you saying you prefer the B+W as it has a more "natural" curve / cut?

2.I think you answered the second question in your latest post... but to be clear both screw onto your lens with the ND closest to the lens, a 77mm to 86mm step up ring and then the B+W (with the large filter size to avoid vignetting) is that correct? and if so what do you do when you use a matte box?

Thanks for your patience!

Schneider is one of the few filter manufacturers that has a series of graphics illustrating the spectral curve for all their filters. There you can see how it gradually cuts the electromagnetic radiation. It's still a 'cut' but not quite as steep a drop as some which I wanted to avoid. Apologies I don't have the link to the charts but it's on their website somewhere. So more gentle in my mind is good for skintones.

Yes, the B+W 86mm is a circular screw-on with 86mm threads that screws onto the outer threads of the SLR Magic Vari-ND Mark II 82mm. The Vari-ND has 82mm threads that screw onto my brass Heliopan step-up rings that screw onto my SLR Magic APO primes.


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Any experience with the Skier brand?
I am having a hard time finding them in 4x4...

I tested them on a BMPCC and found them quite good for the price. Contact them directly about the size, the ones I got for my review were 4x4.

I put the UVIR as the first filter, then the ND, then the lens.

Hey Rick,

I usually don't use Vari-ND filters, but of late have been doing more run-and-gun shooting and have noticed that a lot of folks are liking the SLR Magic Vari-ND Mrk II. Do you know, or does anyone else know, if there is a risk of ghosting or strange reflections if you have the IR cut (like the Hoya UV/IR cut) filter next to the lens and the vari-ND taking the first pass of light?

I take it folks have done tests indicating the best order of glass when using vari-NDs and IR cut, like the Hoya UV/IR cut or the B+W 486M MRC. I, however, have not been able to find those test. Perhaps, this is an old topic.

S

Scott, I don't have a quick link to those tests either, but I am going out to shoot again in a couple of hours without a matte box and the sun low in the sky and plan to try these options on the 85mm APO, maybe 50mm too:

Naked lens

B+W 486 86mm UVIR Cut in front of SLR Magic Vari-ND 82mm

Vari-ND 82mm in front of IE Pro 82mm (not a Cut but a reducer)

B+W 486 86mm UVIR Cut in front of SLR Magic Vari-ND 82mm in front of IE Pro 82mm

repeat, replacing the B+W 486 with Schneider True Cut 715 4x4" via filter whacking...

From my tests yesterday, I had some flaring with the sun near the frame so I just held my hand to shade the lens.

I did recommend having the UVIR facing the subject, first in the path of light to avoid those inner reflections. But with the 82mm IE Pro, I don't have that option when I'm using the SLR Magic Vari-ND Mark II 82mm as the outer filter thread is 86mm. I guess I could buy a step-down ring 86->82mm and hope I don't vignette.

One day I'll have a real matte box and a set of rectangular filters, when I grow up!


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Happy testing and look forward hearing your thoughts

I only had time to test with the 85mm APO, but that should still be a fair evaluation of the various combinations above. I can't wait to put the test video together tomorrow and upload to video.

You know what? Speaking of forgetting to take the lens cap off if I was shooting a nude model, honestly, I didn't check focus! True. I can't believe it! Yesterday, working alone, I checked focus often as I did many different shots. Today, I was so absorbed instructing my model and assistant, I didn't check focus of the single shot I repeated for each combination of filters! And I was exposing using false colour so I don't know what it's going to look like. I don't think I'm going to graduate film school when this gets around! Another story for "Ricky's Believe It or Not!"


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Well. Texting is a good place to make this mistake, I changed a zoom setting on a non parfocal zoom at a directors request to back off the shot, and forgot to refocus (did not have my EVF either). Two mistakes I will never repeat again.

Do you know, or does anyone else know, if there is a risk of ghosting or strange reflections if you have the IR cut (like the Hoya UV/IR cut) filter next to the lens and the vari-ND taking the first pass of light?

This has been my setup (lens -> Hoya UVIR -> SLR Magic VariND) for run and gun situations on the original BMCC, the pocket and now on the 4.6K. It's worked quite well on all of them and I haven't noticed any particular problems with ghosting or reflections. However, I do add a small 86mm threaded rubber hood to the outside of the SLR Magic when necessary, so that may be preventing me from seeing an issue that might occur without the rubber hood.

I only had time to test with the 85mm APO, but that should still be a fair evaluation of the various combinations above. I can't wait to put the test video together tomorrow and upload to video.

You know what? Speaking of forgetting to take the lens cap off if I was shooting a nude model, honestly, I didn't check focus! True. I can't believe it! Yesterday, working alone, I checked focus often as I did many different shots. Today, I was so absorbed instructing my model and assistant, I didn't check focus of the single shot I repeated for each combination of filters! And I was exposing using false colour so I don't know what it's going to look like. I don't think I'm going to graduate film school when this gets around! Another story for "Ricky's Believe It or Not!"


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I've done that before ... not checking focus between switching filters. You have a fairly legit excuse: a naked person in front of your camera - or at least a human. I had focus and color charts I am still undergoing my cinematography remediation plan.

Do you know, or does anyone else know, if there is a risk of ghosting or strange reflections if you have the IR cut (like the Hoya UV/IR cut) filter next to the lens and the vari-ND taking the first pass of light?

This has been my setup (lens -> Hoya UVIR -> SLR Magic VariND) for run and gun situations on the original BMCC, the pocket and now on the 4.6K. It's worked quite well on all of them and I haven't noticed any particular problems with ghosting or reflections. However, I do add a small 86mm threaded rubber hood to the outside of the SLR Magic when necessary, so that may be preventing me from seeing an issue that might occur without the rubber hood.

Thanks for chiming in, Jamie. Seems to me that one would want to cut IR right before the lens and sensor. However, some of the properties associated with IR filters is the they reflect the IR spectrum of light back toward the environment from which it came - potentially, back into the Vari-ND. Now, humans can't see IR, but I wonder if the light could cause some other visible issues. This notion is partly theoretical and may not even matter. Sounds like you aren't have any difficulties, which is great.

Scott, thanks for that encouragement. There was an altercation that occurred before the clips I posted with a rude individual in the park that may have interfered with my ability to be calm and collected. It was a sunny day, but I wasn't feeling sunny personally.


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I'd second the recommendation to put reflective IR (aka hot mirrors) filters first on the outside. Your talent can check their makeup too

1. I am still catching up with the "science" of IR pollution... are you saying you prefer the B+W as it has a more "natural" curve / cut?

I use the Heliopan Digital Filter (yeah, strange name, I know) religiously on all my BM cameras (ND or not), and I never had a IR pollution problem (or color shift).

Here is, what it does (the red curve)

1. I am still catching up with the "science" of IR pollution... are you saying you prefer the B+W as it has a more "natural" curve / cut?

I use the Heliopan Digital Filter (yeah, strange name, I know) religiously on all my BM cameras (ND or not), and I never had a IR pollution problem (or color shift).

Here is, what it does (the red curve)

Hey Frank,

Heliopan stuff is great. I am assuming your Heliopan Digital Filter always sits next to your glass and then you place ND in front? Yes? S

No, I have it on top, since it is cheaper (at least here in Germany) than the VariND

I found in the video I posted Monday, the Schneider True-Cut 715 unfortunately does show some apparent IR pollution, but when paired with the SLR Magic Image Enhancer Pro, it looks better and may be what I use with the matte box especially for beauty shots. When shooting without a matte box, the IE Pro and the B+W 486 MRC combination is great.


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I found in the video I posted Monday, the Schneider True-Cut 715 unfortunately does show some apparent IR pollution, but when paired with the SLR Magic Image Enhancer Pro, it looks better and may be what I use with the matte box especially for beauty shots. When shooting without a matte box, the IE Pro and the B+W 476 combination is great.


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Hey Rick ... was the IR pollution apparent at a particular ND value with the 715? Where'd you get the SLR Magic Image Enhancer Filter. I can't seem to find it anywhere. I am interested in checking it out. Thanks

Scott, I only tested using the maximum strength of the SLR Magic Vari-ND II which is six stops or ND 1.8. You raise a good point that the video illustrates a worst case scenario for the Schneider True-Cut 715 and with lower strengths of ND, the pollution would likely be less. No doubt I'll discover that when I'm shooting for example at T4 or T5.6 or T8 in bright sun, rather than T2.8 where the infrared rays are stronger.

The IE Pro is not yet available from retailers. You can order direct from SLR Magic via support@slrmagic.com. I ordered the IE Pro 82mm because that was the size that fit the 85mm APO, but since I'm using the Vari-ND, the 86mm would also work. I plan on leaving the IE Pro on the 85mm APO semi-permanently but I'll move the Vari-ND to whichever lens I'm using. The 50mm APO has the IE Pro 62mm filter semi-permanently mounted as well.


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In all of our test, you should cut the IR at around 680 which seems to be happening in Franks example.


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James, I agree now! With the Heliopan, which is very effective on BMD sensors, IR is not eliminated until about 750nm. It begins to reduce IR about 640nm and reduces it by 90% about 680nm. As you know all 680nm IR Cut filters have a slope where 680nm is a point on the curve where the IR pollution is no longer evident. The Schneider 715 seemed like a good idea at the time to preserve more deep red, but It is not very effective at stronger ND on the 4.6K sensor. Schneider offers 680, 715, and 750 filters and points out on their website that CCD/CMOS sensors do vary in their sensitivity to infrared and the user can determine which filter works best.

My hope is that I didn't waste several hundred dollars on this 4x4" 715 filter and I can still use it effectively (with the Image Enhancer that reduces IR as well) at lower ND strengths or when shooting narrative interiors. I need to test that. If it fails those tests, then I do have the screw-on B+W 486 MRC that also has a gentle slope and does effectively eliminate infrared pollution even with strong ND about 680nm.


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James, I agree now! With the Heliopan, which is very effective on BMD sensors, IR is not eliminated until about 750nm. It begins to reduce IR about 640nm and reduces it by 90% about 680nm. As you know all 680nm IR Cut filters have a slope where 680nm is a point on the curve where the IR pollution is no longer evident. The Schneider 715 seemed like a good idea at the time to preserve more deep red, but It is not very effective at stronger ND on the 4.6K sensor. Schneider offers 680, 715, and 750 filters and points out on their website that CCD/CMOS sensors do vary in their sensitivity to infrared and the user can determine which filter works best.

My hope is that I didn't waste several hundred dollars on this 4x4" 715 filter and I can still use it effectively (with the Image Enhancer that reduces IR as well) at lower ND strengths or when shooting narrative interiors. I need to test that. If it fails those tests, then I do have the screw-on B+W 486 MRC that also has a gentle slope and does effectively eliminate infrared pollution even with strong ND about 680nm.


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So ... it appears as though one would need the 680 if shooting under tungsten even with no ND with the UM4.6k or if not using large filters, the B+W 486 or IE Pro when using a screw on type arrangement even with no ND. I have not tried my B+W 486 under tungsten yet. Did some tests under sunlight and Vari-ND and things looked pretty good across different black fabrics. My Firecrests using .3 under tungsten showed some IR pollution. Paul DV showed me some tests where there was a lot of IR pollution with the 2mm 4x4 Firecrests under tungsten

Thanks for the link to SLR, Rick. So, you are still putting your IE Pro at first light when using Vari-ND?

Agree, Scott. I'm very happy with my screw-on solution:
Subject -> B+W 486 MRC 86mm -> SLR Magic Vari-ND 82mm (obviously with outside thread of 86mm) -> IE Pro 82mm on the 85mm APO or IE Pro 62mm on the 50mm APO with Heliopan brass step-up ring 62-82mm.

If I don't have the light to support having the Vari-ND on the lens, then I either need to order a Heliopan brass step-up ring to get to 86mm outside. Or just filter whack the B+W which Catalina did well on my Infrared Contamination video.

My rectangular filter solution is up in the air. Still need to test the Schneider 715 with the IE Pro at lighter ND strengths where it might be fine since both filters reduce IR. It's not a good solution at ND 1.8 though as my video demonstrated.

Will you post your results under tungsten lighting? I'd like to see how things look in those conditions.

I'm also thinking I was really playing with Fire in my test with the late afternoon sun shining directly on Gabriela. I'm wondering if the results would be better if I was shooting on an overcast day or the sun higher overhead and shooting with the sun more of a backlight or highlight than the key light.

So many tests to be done, so many battles to be won! I guess the need for testing goes on and on and only ends when you pass on to the great theatre in the sky (that I hear projects video shot with a BMD 4.6K sensor with user selectable global/rolling shutter). For obvious reasons, 'They' don't use GPS up there on the cameras though since 'He' is everywhere!


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Agree, Scott. I'm very happy with my screw-on solution:
Subject -> B+W 486 MRC 86mm -> SLR Magic Vari-ND 82mm (obviously with outside thread of 86mm) -> IE Pro 82mm on the 85mm APO or IE Pro 62mm on the 50mm APO with Heliopan brass step-up ring 62-82mm.

If I don't have the light to support having the Vari-ND on the lens, then I either need to order a Heliopan brass step-up ring to get to 86mm outside. Or just filter whack the B+W which Catalina did well on my Infrared Contamination video.

My rectangular filter solution is up in the air. Still need to test the Schneider 715 with the IE Pro at lighter ND strengths where it might be fine since both filters reduce IR. It's not a good solution at ND 1.8 though as my video demonstrated.

Will you post your results under tungsten lighting? I'd like to see how things look in those conditions.

I'm also thinking I was really playing with Fire in my test with the late afternoon sun shining directly on Gabriela. I'm wondering if the results would be better if I was shooting on an overcast day or the sun higher overhead and shooting with the sun more of a backlight or highlight than the key light.

So many tests to be done, so many battles to be won! I guess the need for testing goes on and on and only ends when you pass on to the great theatre in the sky (that I hear projects video shot with a BMD 4.6K sensor with user selectable global/rolling shutter). For obvious reasons, 'They' don't use GPS up there on the cameras though since 'He' is everywhere!


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I will post a Dropbox link tomorrow. Again ... Thanks for all the details and explanations.

Sorry for the delay, Rick. I have been slammed. Here is a link to some jpeg stills - graded and ungraded. I was shooting under 750 watt Lekos 3200k and a dimmed 2200k practical. The background was a rear projection screen (6500k). I recall one par 3200k in front had a straw filter. I was using a Firecrest .3 4x5.65 and Zeiss 35mm/T1.5 lens at T2.2.

As you can see, there is some IR pollution - particularly, in the bass player's jeans that are a spandex/cotton mix. The black cotton jackets faired well. The synthetic blacks are a pain. In this music video, I did my best to stay away from wide shots with pants.

Just so you know, I picked up a B+W 486 and a SLR Magic Vari ND, based on your thoughts for my Sigma ART zooms. I did some tests the other day and found this combo very nice. The SLR Magic nicely maintains sharpness compared to my other Vari-ND. I found the B+W 486 a little better at controlling IR pollution than the classic Hoya (interesting finding), but does add a very minor slight green tint (but not objectionable at all).

Appreciate your tests and findings.

https://www.dropbox.com/sh/xc0gkne5107p ... zYrga?dl=0

Scott, thanks for those DNGs under lights. And glad you like the B+W 486 MRC with the SLR Magic Vari-ND Mark II. I am quite comfortable now using that combination. The Vari-ND has a slight yellow cast that shows up most at the Max 6 stops, but I like it on the URSA Mini 4.6K. I'd rather see skin a bit yellow rather than a bit green or pink.

As for being busy, I'm finding it difficult to keep up with my assignments. Spending much less time on the forums sadly.

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Here's the video Scott mentioned. The 680 does cut enough but the image goes a tiny bit green. That's fine though because you can adjust the tint and correct it out.

Thanks, Paul. Green is probably a more post friendly issue than IR pollution in blacks!


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Sure. It's much easier too correct some general green tint than a purple one that affects only some blacks and not the others or a yellowish one on natural green and not the artificial greens in painting or clothes.