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04-27-2013, 01:24 PM   #1
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Affordable (relatively speaking) IR reduction solution for 85mm ND.

If this info has been posted before do forgive me.

So, part of an equipment upgrade I'm undertaking has been adding 85mm ND/GND/RND filters. I purchased a Hitech three filter kit and a Hitech Master Kit. The three filter kit includes the basic plastic Cokin P style holder, the Master Kit does not.

http://www.2filter.com/prices/Hitech/HitechP.html#7708

(if you want several common values of ND and GND, order one three filter set then order the appropriate six filter "Master Kit". You'll have to order by phone to get this arrangement, it's not on their website There is also a three filter RND set available but I don't know for sure if 2filter.com carries it; B&H does).

Now that I have the ND kits I want, I need to consider IR control since I will probably end up with 1.2 values shortly. There was the option to purchase 85mm ND filters with IR cut built in but the cost difference is enormous and a dedicated 85mm IR cut filter or hot mirror doesn't appear to exist. Since an IR cut or hot mirror has to be placed in front of the ND filters, a relatively inexpensive circular one was also out. Or so I thought.

I found the following to be a potentially affordable solution and thought I would share. Hitech have only recently offered this and US suppliers seem to be having a hard time getting in the lens adapter rings. So, I ordered the holder from the UK which provides me plenty of time (about a month for US delivery) to compare the pros and cons between a simple IR cut filter like the B&W one, or the more expensive (but still less expensive than any rectangular or square version) Hot Mirror by Formatt.



Hitech 85mm Aluminium Modular Holder : Buy Hitech 85mm Aluminium Modular Holder online : Formatt Filters

Hitech 85mm - 95mm Front Accessory Ring : Buy Hitech 85mm - 95mm Front Accessory Ring online : Formatt Filters

IR Control| B&H Photo Video


Last edited by MD Optofonik; 04-27-2013 at 07:19 PM.
04-27-2013, 08:42 PM   #2
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Be aware the more filters you stack the greater the chance that flare will ruin your image more than IR contamination will. It also really depends on the camera you are using - the K5IIs I have has perhaps the lowest sensitivity to IR of any camera I own, to quote DALSA:

" CMOS imager fabrication processes are tuned for high volume applications that only image in the visible. These images are not very sensitive to the near infrared (NIR). In fact, they are engineered to be as insensitive as possible in the NIR"

Though Having said that I am not familiar with the Pentax K2000 DSLR - so YMMV. With my older Pentax K10D when used with the Hoya R72 filter the Internal Hot mirror would attenuate IR to the point where my exposure times were 30 seconds @ f/11 and that was at nigh noon in full daylight.

In short I wouldn't consider IR control measures unless it is visibly impacting image quality,I have been using the Lee "big stopper" ND10 filter - sometimes stacked with a polariser and I have yet to see any significant problems with IR.

Last edited by Digitalis; 04-27-2013 at 08:53 PM.
04-28-2013, 12:39 PM   #3
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QuoteOriginally posted by Digitalis Quote
Be aware the more filters you stack the greater the chance that flare will ruin your image more than IR contamination will. It also really depends on the camera you are using - the K5IIs I have has perhaps the lowest sensitivity to IR of any camera I own, to quote DALSA:

" CMOS imager fabrication processes are tuned for high volume applications that only image in the visible. These images are not very sensitive to the near infrared (NIR). In fact, they are engineered to be as insensitive as possible in the NIR"

Though Having said that I am not familiar with the Pentax K2000 DSLR - so YMMV. With my older Pentax K10D when used with the Hoya R72 filter the Internal Hot mirror would attenuate IR to the point where my exposure times were 30 seconds @ f/11 and that was at nigh noon in full daylight.

In short I wouldn't consider IR control measures unless it is visibly impacting image quality,I have been using the Lee "big stopper" ND10 filter - sometimes stacked with a polariser and I have yet to see any significant problems with IR.
In addition to the K2000 (CCD) I've got a K30 (CMOS) and although the K30 is somewhat related to the K5/II/IIs, I'm not sure it's IR filter would be on par. It seems that high quality internal IR filters/Hot Mirrors are one of the more pricy components in any DSLR. I imagine Pentax's budget cameras may not use the same IR filter as the K5/II/IIs. It would be nice to know one way or the other, though.
04-28-2013, 08:10 PM   #4
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Well I would suggest you test the Camera with the filters, under full daylight and posting the results - it will be interesting to see if there is a problem or not. Though I doubt pentax would have skimped on the Hot mirror built into their cameras - a weak UV/IR filter can wreak havok on colour rendering.

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