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View Full Version : How important is an IR filter?



Simon Shasha
09-18-2012, 01:33 AM
Hey guys,

I've got a set of these ready to go for my Sigma 20mm F1.8 and Sigma 10-20mm F3.5 (also have a set of set-up rings to be able to use the NDs on my Sigma 30mm F1.4 and Tokina 11-16mm F2.8): http://www.bhphotovideo.com/c/product/674667-REG/Tiffen_82NDK3_82mm_Digital_Neutral_Density.html

I've been using a variable ND (Light Craft Workshop) for years with my Canon DSLRs, so I'm new to screw-in ND filters. I've been warned about IR contamination. I've heard in RAW, IR contamination isn't really a problem as you can set white-balance later. However, for me, I plan to shoot ProRes for the first few months. How important is it that I buy a IR filter? - They're so expensive :(

Jason M.
09-18-2012, 07:50 AM
Far-red contamination (don't think it's IR in this case, though the two terms are used pretty interchangeably) will still be a problem in RAW, at least in certain situations. It changes the color in specific parts of the scene (some blacks), not overall. Basically, use a Tiffen T1 filter whenever you go over ND 1.2. Or, get an ND set, and then get an ND/IR 1.2 filter. These are what I'm going to be using, for example:

http://www.bhphotovideo.com/c/product/729107-REG/Tiffen_W77INDNDKT_77mm_Indie_Neutral_Density.html

with this:

http://www.bhphotovideo.com/c/product/688433-REG/Tiffen_W77IRND12_77mm_Combination_Neutral_Density. html

That combo will cover up to 8 stops of ND, and have the IR cut when needed.


The T1 filter is here, though if you have the ND/IR, you don't necessarily need it:

http://www.bhphotovideo.com/c/product/658765-REG/Tiffen_W77IR_T1_Infrared_Filter_77mm.html

I hear you on the expenses, but good glass (both filters and lenses) is going to be somewhat pricey. In the end, though, it usually pays off in terms of image quality.

Simon Shasha
09-19-2012, 01:04 AM
Thanks so much for the input, Jason, very helpful :)

I just contacted a reseller in Sydney for the Tiffen 82mm T1...they want $251...another reseller wanted nearly the same price...both said "six-week waiting period". I can order it from B&H, have it delivered within four-days and still save around $120...we always get shafted on pricing in Australia.

Simon Shasha
09-20-2012, 01:48 AM
Hey Jason, what do you think of this one?: http://www.bhphotovideo.com/c/product/807811-REG/Tiffen_W82IRND21_82mm_Solid_Neutral_Density.html

I'm trying to find a filter that lets me stay at F2.8 @ ISO800 in daylight, and cut the infrared at the same time.

Jason M.
09-20-2012, 07:40 AM
2.8 in daylight (or at least direct sunlight) at ISO 800 is a lot of ND. Just calculating from the "Sunny 16" rule, you'd need 9 stops of ND, or ND 2.7. That said, in most practical daylight situations, you might not ever need quite that much ND.

So the 2.1 ND/IR filter you linked to would definitely work pretty well for that, but it's going to be much less flexible for situations that don't call for f2.8 in sunlight. If you're only ever going to shoot outdoors in the sun at ISO 800, then it may well be worth it, but I still think you'd have better flexibility with a 1.2 ND/IR, and then add additional normal ND as needed. If you already have that normal ND set from B&H, all you'd need would be a normal ND 0.3, and you'd have the entire range covered from 0.3 to 2.4 IR. Unless you want to buy a single filter for every situation (since if you got the 2.1 ND/IR, you still might need 1.2, 1.5 and 1.8 ND/IR), I think using the 1.2 ND/IR and stacking additional ND filters is the way to go here.

http://www.bhphotovideo.com/c/product/807746-REG/Tiffen_W82IRND12_82mm_Solid_Neutral_Density.html

If there's something I'm missing here, someone else feel free to chime in.

nickjbedford
09-20-2012, 08:19 AM
Yeah daylight shallow depth of field will be an interesting one.

That being said, there are a lot of wider shots where it'll be perfectly fine to get rid of some NDs and go deep on your aperture.