Filming in the desert - which IRND ?

[tetsujin28]

In April I'm in the desert of Almeria to film a music video.
Currently I have 4 IRND filters (0.3, 0.6, 0.9, 1.2) of the Tiffen brand.

I was told that the brightness of this place was extreme.
I would like to have your opinion on additional filters that I should have.
I don't what to expect there, so I will also gladly take any kind of advice on filming in the desert.

Thank you

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Photo taked by my spanish assistant in place

[Animotion]

Fist thing, ditch the tiffens and get Hoya. My tiffens have a very slight green shift. It may be a different situation if you have water whites. 4 stops seems like it may be enough though for the high end.

[vicharris]

Yeah, if you're going for a paid project, trash the Tiffens man. Well, sell em to fund the Hoyas. You're going to need at least 1.8 in the desert as well. You can stack the Hoyas, doing that with the Tiffens would scare the crap out of me. If you haven't done any research, you need to search the threads here for Hoyas and Tiffens. I have a whole thread with the Tiffens and how wrong they are for the camera.

Maybe a Cir Polarizer as well.

[Howie Roll]

Vic is right on, at least 6 stops. According to sunny 16 you'd need 8 stops of nd to shoot f4 at 800 iso, 6 stops would yield an f8. The tiffens are probably fine as long as there is nothing black in the shot, insert humor emoticon here.

[CaptainHook]

Yep, check out my comparisons of the new Hoyas to the Tiffen IRND's here:

Pocket Cam - http://www.bmcuser.com/showthread.ph...ll=1#post97497
4K Camera - http://www.bmcuser.com/showthread.ph...l=1#post108645

I feel a little "dirty" posting this, but i have had some 'success' working on a LUT to help with IR contamination on the BMDcams.

Here's a frame with the Tiffen 1.2 4x4 ND with NO IR cut filtration:



And here's the same image with my IR Cut LUT before all other nodes:



Not perfect i know and it's just the start and will be a work in progress, but still a much better place to start a grade.

It's in my 'donators pack' (hence the reason i feel dirty mentioning it) from here:

http://www.bmcuser.com/showthread.ph...BMDFilm-Extras

[tetsujin28]

Hoya looks interresting but I am working with 4x4 filters and 4x6.5, and as I remember Hoya doesn't make square filters, is it ?

I went square filters because I have a wide variety of zoom and primes and I thought it was complicated to have multiples on lenses filters with multiples diameters and values, I am also a big fan of filters on cam like pro mist ...

Anyway if I understand well I have to go with something stronger 1.8 or 2.1 (6 or 7 stops down) with a circular polarizer, many of lenses have a sweet spot at around F5 so it could be okay.

[vicharris]

Hoya looks interresting but I am working with 4x4 filters and 4x6.5, and as I remember Hoya doesn't make square filters, is it ?

Ahhh, yep. Is it possible to use a 77mm ir cut filter on your lenses, like a standard uv filter one? Maybe a TrueND IR cut filter. If not, shoot raw and get that LUT from hook cause you're going to need it! That 2.1 IRND Tiffen is the worst filter I've ever seen. Not sure if you can rescue anything from it.

[tetsujin28]

@CaptainHook
Your post is very interresting because I saw with IRND filters and in some circumstances there is always and IR color shift that need to be corrected.

[tetsujin28]

Ahhh, yep. Is it possible to use a 77mm ir cut filter on your lenses, like a standard uv filter one? Maybe a TrueND IR cut filter. If not, shoot raw and get that LUT from hook cause you're going to need it! That 2.1 IRND Tiffen is the worst filter I've ever seen. Not sure if you can rescue anything from it.

Yes I only work with raw files and that was the main reason of buying a BMCC

Maybe If I buy a Schneider IR filter at 680 nanometers and some choosen hoya ND on lenses or Schneider square ND it could work well, anybody test that sort of configuration ?

By the way CaptainHook
your work and "donations" are greatly appreciate in the BMCC community, i am glad that you are here and same for the others cinematographers here

[tetsujin28]

@VicHarris
The Tiffen IRND you tested are the hot mirrors (dichroic) or the newer full spectrum ?
Both technolgies are different.

I read on the internet that the HM have a noticeable magenta cyan color shift and the full spectrum are really better.
I also remember the Abelcine test where they test the full spectrum if I remember well.

[vicharris]

I tested the regular IRNDs, not the HM. Same with Hook. I called Tiffen and the acknowledged the problem with BM cams as well. Said there's nothing they can do, it's the sensors. We all had a huge, green color shift though the 2.1 turned everything red.

Tried to get a hold of Able as well but they never returned any correspondence.

[tetsujin28]

I tested the regular IRNDs, not the HM. Same with Hook. I called Tiffen and the acknowledged the problem with BM cams as well. Said there's nothing they can do, it's the sensors. We all had a huge, green color shift though the 2.1 turned everything red.

Tried to get a hold of Able as well but they never returned any correspondence.

This is pretty bad I had some trust in Tiffen.
I have a few weeks before going to Almeria, I will make some test with Schneider and Hittech if I have time I will report the results here, anyway be sure that I will post the music video here also and talk about what I use.

Thanks

[Steve Wake]

Maybe If I buy a Schneider IR filter at 680 nanometers and some choosen hoya ND on lenses or Schneider square ND it could work well, anybody test that sort of configuration ?

I don't know if you are planning to use wide angle lenses, but if you are, just be aware that you can start to get cyan or green vignetting if you exceed certain angles of view on DICHROIC/HM IR cuts. Dye/absorption type IR cuts like Tiffen non-HM or Schneider Platinum wouldn't have this vignetting problem, but of course could have other color cast problems.

Kholi recently found that the limit for the Hoya IR cut, which Hoya say cuts at 700nm, was around 12-14 mm focal length on the BMPC 4K sensor. Too wide and he reported green vignetting. Since this color vignetting of dichroic filters is directly related to the AOV, I estimated the critical AOV at about 77 degrees. The critical AOV will be the same for any sensor/focal length combination. The critical focal length for a different sized sensor will be related to that AOV.

After that report I asked Schneider about AOV limit on their 3 different dichroic IR cuts, which cut at 680, 715 and 750nm. Paraphrasing: they said they didn't have a spec on that, but in general, the 750 can be safely (no color vignetting) used with up to mid-wide lenses, 680 up to normal lenses, and 715 in-between. These are probably conservative estimates. The Hoya UVIR cuts at 700nm - though since it's a different brand with presumably different dichroic coating layers the AOV limit probably can't be compared directly. Per Schneider, the nm rating is based on the point at which transmission is 50%. That is, it starts the sharp cut typical of a dichroic at a slightly shorter wavelength than the rating.
If you ARE planning to use any lens that could be called wide or wider, I'd recommend testing before you go with any dichroic IR or IRND.

No, I haven't tested Schneiders, but testing with the B+W 486M dichroic and the Hoya UVIR dichroic has convinced me that the basic trend Schneider described for their IR cuts is valid.

[MelbFilm]

Funny, I posted about 9 months ago that I thought my Tiffen 1.8 White Water looked rubbish (Kind of murky brown) on my BMCC and just I assumed it was something I had done. Glad to know I was not going mad.

It is now basically an expensive drinks coaster.

[tetsujin28]

@Steve Wake
The multiple sites I saw on internet shows that 680 nanometers IR cut works best on the BMCC but you point something interresting the 4k version of the camera seems to work better with a higher value (planning to buy that beast).



And for my desert problems I think more and more about the Schneider Platinum as where I live this year they are easy to find (tiffen are quasi or totally inexistant).

I read on Schneider site :

Schneider Platinum Series IRND filters are free of off-axis color shift regardless of the focal length and can be stacked without introducing reflections common in dichroic filters

I will certainly use a Tokina 11-16 on some scenes so you are right Steve some test are mandatory