Dillema: IRND filters vs ND filters. IRND is duplication of ND?

[Alexey Datsenko]

Some dilemma, trying to buy set of filters and see the most useful are ND filters 0.3,0.6,0.9,1,2.
It is for light reduction. But IRND filters for light reduction and plus protection against color shift because of infrared light.
So can IRND filters give the same effect as ND filters concerning light reduction or is it the different filters for different purpose? So can IRND be used as ND and plus IR protection as a bonus? For example is the client asking about ND filters and he would get IRND instead of ND he would be able to get the same results with IRND which he planed to get with ND initially or he wouldn't be?

 

[albert rudnicki]

Same thing, but I find IRND troublesome when you sandwich them with other filters, may get ghosts.
up to .6 you don't need IR, simple ND
over that get IRND

 

[Alexey Datsenko]

So if I will be shooting for examples with IRND 0.9 and 1,2 can I get the same results as I would be shooting with ND 0.9 and 1.2? and plus protection against color shift from infrared as bonus? Or is it two different results?

 

[Brian F Kobylarz]

The IRND should always be the outermost filter - reflective surface is not designed to be inside a stack.

Makes sense to own both IRND and some standard ND's - if you need to stack, plain ND always goes behind the IRND. Do not stack IRND's and the ghost will not appear.

If you already own standard ND's, look at a Schneider True-cut 750. Again, that will be the outermost filter.

If you are buying new, consider the platinum series or the Formatt's too.

A search on this forum can find many tests between brands - or run tests of your own...

 

[Alexey Datsenko]

Is it well to use two filters or is there some problems with it? For example if use True-cut 750 and some ND?

 

[Brian F Kobylarz]

You might use something like a standard ND 1.2 to allow you to open up the lens and add a True-cut 750 to take out some of the IR.

Or

You might use a single filter such as a 1.2 IRND to accomplish the same thing.

Or

You might use a standard ND 0.3 and a 0.9 IRND if you don't own one of everything.



Remember - do NOT stack IR's and any IR filter must be the outermost filter.

Anytime you can eliminate a filter from a stack, you reduce the possibility of contaminating the optical path.
Stacking ND's can introduce shifts - so if you need to get to a certain value, try to reach it with the least number of filters.

 

[Ned Wilson]

I use Tiffen IR12,15 and 18. I'll be adding a 9 as well. I don't see IR contamination at .9 but if you use it with a Pola then you will. I believe in using combo filters whenever you can just so you have trays available for other filters. Sometimes I'll have an IRND, Pola and Grad in the box. IR contamination really sucks. Hard if not impossible to get out in post and retain your match with un contaminated shots. I'd love it if Red came out with internal filtering.

 

[Tom Digges]

Is what an IRND is doing considered a reflection of IR waves? Because if so, is there a directionality that the filter must face for it to reflect properly? Or is one side of the filter just as effective as the other?

 

[Clayton Burkhart]

There is a little bit of confusion here. You CAN stack IRND's, you CANNOT stack Hot Mirror IRND's.
IRND's absorb infrared light, Hot Mirrors reflect it. Therefore, you don't want hot mirrors refecting off of each other.
Therefore a hot mirror is always the outermost one. That's it.
After that, in general it is best to have as few filters as possible in front of the lens. So obviously a single hot mirror ND is
more helpful than a combo set.
There is a proper orientation to a hot mirror, it is usually a surface coating, so that side MUST face outwards.