Author Topic: Any 5D3's IR issue with VND filters? (BlackMagic does have)  (Read 1817 times)

adrjork

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Any 5D3's IR issue with VND filters? (BlackMagic does have)
« on: March 29, 2017, 01:38:52 PM »
Hi everyone,
when I considered to buy a BlackMagic camera I've read about IR issue using VND filters. That issue could be solved using an IRVND filter instead.
But finally - thanks to you guys! - I decided to go for a 5D3 with MagicLantern (and I'm so happy about that choice!)

Now I simply need to know if - doing RAW video - my 5D3+ML needs an IRVND, or if I can use a normal VND without problems?

Thanks for your help.

P.S. Tiffen or Promaster? (Because on one VND by Tiffen I noticed an X effect...)

ewinemiller

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Re: Any 5D3's IR issue with VND filters? (BlackMagic does have)
« Reply #1 on: March 29, 2017, 04:50:50 PM »
Since it takes about 30s+ to get a decent exposure when using my IR filters, I suspect for most video exposure time you won't have a problem with the 5D3.

I think the X effect is more a basic problem with stacked polarizers (the typical mechanism for building a VND) and wide angle lenses. Does the Promaster work on some different principal?

I use the Tiffen and have been happy.

garry23

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Re: Any 5D3's IR issue with VND filters? (BlackMagic does have)
« Reply #2 on: March 29, 2017, 05:29:48 PM »
Just in case it helps, I personally use the NDthrottle VND on my 5D3, with a Mamiya lens: https://fotodioxpro.com/products/m645-eos-p-ndthrtl-dc

This eliminates the dreaded X effect.

adrjork

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Re: Any 5D3's IR issue with VND filters? (BlackMagic does have)
« Reply #3 on: March 29, 2017, 07:36:37 PM »
Thanks guys!
So, I can go for a regular Tiffen VND without worring about IRVND rare variant.
Thanks

adrjork

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Re: Any 5D3's IR issue with VND filters? (BlackMagic does have)
« Reply #4 on: March 29, 2017, 08:50:55 PM »
P.S. Just a doubt: you say that the problem refers Wide Lenses, so...
1. With a 35mm is better to use fixed ND filters;
2. With a 85mm I can safely use a good VND.

That's right?

garry23

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Re: Any 5D3's IR issue with VND filters? (BlackMagic does have)
« Reply #5 on: March 29, 2017, 09:00:57 PM »
Yes, that's about right.

Polarizers and 90 degrees to the sun, all lead to the X effect.

Which is why the ND throttle works irrespective of FL, as its at the rear of the lens.

adrjork

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Re: Any 5D3's IR issue with VND filters? (BlackMagic does have)
« Reply #6 on: April 07, 2017, 09:18:46 AM »
Thanks for your reply,

if I use 2 different fixed-NDs together, this will give the same X-issue of the VNDs or not?

Thanks for the help.

garry23

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Re: Any 5D3's IR issue with VND filters? (BlackMagic does have)
« Reply #7 on: April 07, 2017, 09:26:30 AM »
No stacked NDs will not give the X effect, but they may give vinetting issues of you choose the same diameter as the lens thread.

I would consider getting thin NDs if stacking.

You can also buy larger NDs and step up rings.

I have 150mm NDs!

Also stacking NDs may bring in more colour cast issues.

Cheers

Garry

adrjork

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Re: Any 5D3's IR issue with VND filters? (BlackMagic does have)
« Reply #8 on: April 07, 2017, 09:34:20 AM »
You are a super-fast guru Garry.
Thanks!

When you staking, the values of the 2 ND are summed or multiplied?
If for example I have 0.6 + 1.2, they are equal 1.8?

Again, Thanks!

garry23

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Re: Any 5D3's IR issue with VND filters? (BlackMagic does have)
« Reply #9 on: April 07, 2017, 09:40:10 AM »
@adrjork

Summed. Thus 0.6/2stops + 1.2/4stops = 1.8/6stops.