patrickbaldwin
Well-known member
Does anyone have any preferences/recommendations for an IR cut filter? Screw on and matte box types.
Many thanks. Patrick.
Many thanks. Patrick.
FS5: IR cut filter recommendations
- Thread starter patrickbaldwin
- Start date
Imamacuser
Veteran
A lot of BlackMagic shooters use screw-on Hoya IR cut filters. I think SLR Magic's Image Enhancer filter is just an IR cut filter. B+W's IR cut filter affects a slightly different nanometer range than the Hoya, so which one you get really depends on how big a swatch of light waves you want to cut.
Tiffen made a filter specifically for the EX-1/3 series (T1) and that may be closer to what's needed for the FS5, though at least on FS7 it didn't seem to be needed. I'm surprised it was apparent on the FS5. Frankly on my computer monitor I didn't see that magenta but I might have been crushing the blacks. Iff you just put a bunch of different black fabrics in front of your camera you should be able to see a difference where some them will go magenta . With me the iron clad test was a black "Russel Athletic" sweatshirt . If that didn't go magenta I knew I was OK.
The problem may increase though if you're outdoors and using ND that doesn't cut the increased IR that just comes from more light. (More light = more IR ) So you might test those fabrics both outdoors using various kinds of ND and indoors without any. I mention this because your sample was outdoors in apparently bright sun. Its really hard to cut IR contamination in post. I once worked a product rollout video with an EX-1 where they blocked out the entire stage with drapes and black fabrics over tables + all the on camera talent was wearing black. What a nightmare - every fabric had a different color - though to the eye they were all the same.
I usually found that the internal ND filters on most cameras corrected for IR but I wonder if the electronic ND on the FS5 behaves differently. The problem with IR cut filters is that you often have to white balance through them to get rid of the cast they create and that means you can't just rely on preset Kelvin.
As a poor man's solution, after trying a host of expensive IR ND filters on the EX-1 I found that just using B+W or Heliopan Round ND's seemed to work as ND that got rid of the IR . Worth a try anyway.
The problem may increase though if you're outdoors and using ND that doesn't cut the increased IR that just comes from more light. (More light = more IR ) So you might test those fabrics both outdoors using various kinds of ND and indoors without any. I mention this because your sample was outdoors in apparently bright sun. Its really hard to cut IR contamination in post. I once worked a product rollout video with an EX-1 where they blocked out the entire stage with drapes and black fabrics over tables + all the on camera talent was wearing black. What a nightmare - every fabric had a different color - though to the eye they were all the same.
I usually found that the internal ND filters on most cameras corrected for IR but I wonder if the electronic ND on the FS5 behaves differently. The problem with IR cut filters is that you often have to white balance through them to get rid of the cast they create and that means you can't just rely on preset Kelvin.
As a poor man's solution, after trying a host of expensive IR ND filters on the EX-1 I found that just using B+W or Heliopan Round ND's seemed to work as ND that got rid of the IR . Worth a try anyway.
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patrickbaldwin
Well-known member
Thank you.
patrickbaldwin
Well-known member
Thank you very much for this. My skills don't go anywhere near to correcting this in post. Magenta was a bad choice of words. It's more a red/brown colour. The jpeg in the other thread is crushed compared to the video so it's a little harder to see compared to the video but it's night and day obvious on my monitor. I was rolling the variable ND all day there as the sun moved in and out of clouds. Would having the inbuilt ND operating make a difference or even cause this?
Many thanks. Patrick.
I'm not sure what you mean by the "in-built ND" and I'm not familiar with the FS5's ND system at all. However you should just experiment . Get a bunch of black materials from your own clothes and anything you can find and then look at it under different lighting conditions and with different ND's. You can always buy ND's and IR cut filters from B&H and return them if they don't work. Let us know what you come up with .
BTW - Its really hard to fix this in post so don't be hard on yourself.
BTW - Its really hard to fix this in post so don't be hard on yourself.
patrickbaldwin
Well-known member
Hi Lenny. I meant the electronic infinitely variable ND that the FS5 has.
Thank you very much for taking the time to help me. I really appreciate it.
Patrick
Run&Gun
Veteran
This could be a problem that none of us have really thought about before. Most ND systems in cameras are glass disks of set strengths of ND that could have built-in correction for IR(the stronger the ND the bigger the potential for IR contamination, unless it is accounted for).
patrickbaldwin
Well-known member
Oh dear. I can see some serious testing in my future to get to grips with this!
Thank you for making the point.
Ben_Ericson
Well-known member
I am surprised this is an issue with the FS5. Seems like a flaw if you can't use the internal NDs without tampering with the image. The c100 and 300 does not have this issue. My F3 does in studio environments (Hot tungsten lights.)
Bern Caughey
Veteran
JPNola
Veteran
user discussion with good info ( and probably some bad info as well ). Consume with discretion. Perform your own tests if possible. Consider purchasing two different makes / types of IR ND and keep the one you find best for yourself, return the other. Then build a complete set of the type you found best.
http://www.cinematography.com/index.php?showtopic=67332
Consider this quote from that linked discussion, from a respected DP:
"Sony require IRNDs but if you are using the internal NDs on the cameras which already have IR built in, then you can probably get away with straight NDs up to about N6."
If I had to just throw out one make and type of IR ND for you, I'd say to go with the Firecrests. That is, Formatt Hitech Firecrest ND filters.
http://www.cinematography.com/index.php?showtopic=67332
Consider this quote from that linked discussion, from a respected DP:
"Sony require IRNDs but if you are using the internal NDs on the cameras which already have IR built in, then you can probably get away with straight NDs up to about N6."
If I had to just throw out one make and type of IR ND for you, I'd say to go with the Firecrests. That is, Formatt Hitech Firecrest ND filters.
NorBro
Major Contributor
Several years ago when comparing the Alexa with the C500, Shane Hurlbut thought Canon's IR filters were very strong:
https://www.youtube.com/watch?v=q8gJcC0i7uI
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Also FWIW, the FS5 has one more stop of ND than the Canons.
patrickbaldwin
Well-known member
That is a good point. If this is a problem with the FS5 I cannot possibly be the first person to see it.
patrickbaldwin
Well-known member
Unfortunately I live in the UK and I don't think I know of a dealer with the return policy that B&H has. I would have to rent which is possible of course.
I will definitely read through the thread you linked to and thank you for the recommendation of the Firecrests.
Many thanks. Patrick.