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Thread: ND filters for MFD

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    New Member Plateau Light's Avatar
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    ND filters for MFD

    Hi

    I have had some poor results with ND filters for long exposures and have read that the IR blocking ability plays a big role in the IQ on MFD long exposures.
    I have used some 6 and 10 stop resin filters for my Lee system with poor results. I got bizarre red halation spots on red/magenta areas and low contrast on 40 to 60 second exposures. I tracked some of it down to the display of my H3dII 50 being on during long exposures, so I turned that off. There is still some red area blooming or color weirdness on these ND shots that I am attributing to the quality of the filter itself.

    I was wondering what the "good" IR blocking ND filters I had briefly read about in a thread were. They are expensive and I would rather make the right choice.

    Thanks

    Robert

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    Sr. Administrator Jack's Avatar
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    Re: ND filters for MFD

    I use and reco Tiffen IRND. I carry a 6 stop and a 3 stop in 77mm, and then step rings for all my lenses. I can still see through the 6-stop to compose, and I can add the 3-stop on the rare occasion I need more than 6 stops. They aren't perfect for exacting color, but are very good -- and WAYYYY better than regular ND's.
    Jack
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    New Member Plateau Light's Avatar
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    Re: ND filters for MFD

    Jack,

    Thanks. I didn't even think to look up IR ND filters. It looks like both Tiffen and Schneider offer products.

    Thanks again!

    Robert
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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: ND filters for MFD

    If you are seeing red halation then I would make sure that everything is light tight. I use the LEE system for long exposures with my Phase One gear and I found that in daylight that the body/back interface is not 100% light tight when you get in to exposures in the minutes. Also the eyepiece, even if you have a blind, may not be 100% light tight either and needs masking with tape.

    For the Big Stopper and extra ND you need also to block any additional light entering between the filters. I do this by taping around the pair using gaffer tape. In fact, if you see me shooting with my gear you'll see gaffer tape all over it!

    With the LEE filters you may see a blue/cyan colour shift. It isn't the pink/magenta IR contamination that you get with other non-IR blocking filters. If you want regular circular ND filters then I also use the same as Jack - Tiffen IRNDs. I use a 6 & 7 stop combo - one 77mm and the other 82mm so that I can stack them for 13stops.

    These are with the LEE big stopper:
    This is an example of light leaks on a DF/IQ160 combo:


    This is 'sealed' with gaffer tape (or a beanie hat in this case):


    Here's what the combo can look like with stacked 10 & 3stop LEEs:


    Body/Back interface (actually it's not really a problem on the Alpa but it is with a DF):


    Can you share an example of the images with the halation? It would help point you in the right direction because it may not be the filter at all.
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    Re: ND filters for MFD

    +1

    What problem are you referring to? The magenta cast is coming from IR contamination, but the line down the right side of this image is a light leak through my viewfinder--I now use a cover over the view finder.



    I also use Tiffen IR cut filters now over my B+W ND filters to control the IR contamination, but the Tiffen IRND filter are better. I also find the Hoya 9-stop NX400 ND filter to be good.
    Last edited by Shashin; 27th March 2013 at 12:03.

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    New Member Plateau Light's Avatar
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    Re: ND filters for MFD

    I will do a sample later this eve under the same conditions as when I get issues.
    It is definitely not a light leak. After 14 years of shooting 4x5 I know exactly what a light leak looks like. It is only on certain colors too, magenta's to be exact, that are problematic. I think the Tiffen web page tells a lot about a spike in the near IR when using a regular ND.

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    Re: ND filters for MFD

    So, that is IR contamination. How much you can eliminate that is also subject dependent. Foliage is really hard because of near IR response where seascapes are easy.

    But the Tiffen IRNDs or Hoya NX400 are better than B+W. Tiffen also makes an IR cut filter which you can use in your filter stack.

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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: ND filters for MFD

    Without seeing the example it's obviously a little hard to generalize so apologies if the light leak was a distraction.

    The magenta/pink colour cast though is normally the give away for IR contamination and that is where the IRND filters fix things. You might also want to look at the LEE glass ND filters vs resin as these have a stronger IR cut off. However, as mentioned, the gold standard is the Tiffen IRND filter or a combination of other ND with an IR cut hot mirror filter.

    Another thing to watch for with IR cut is how evenly it applies to wide angle glass. For example, if you use an IR cut hot mirror filter from B+W on wide/super wide glass you can get an uneven colour cast due to the way that they filter IR. With my full spectrum camera I had to use filters using IR absorption from Kolarivision which avoided the issue. Depending upon the sensitivity to IR and the glass you use the actual coatings can also make the IR filtration different across the lens from the center outwards.
    Remember: adventure before dementia!

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    New Member Plateau Light's Avatar
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    Re: ND filters for MFD

    So here is a set of 64 second exposures.

    It looks like the ND itself is not the issue. It is IR from the incandescent lights in long indoor exposures. I shot the same scene with filtered skylight and the incandescent and the result is obvious. When the IR is present it screws up the long exposure on the 50mp Hassy.

    For some reason I get the red shifts on some twillight images when I use the ND for special effects. There must be some residual IR at that time.
    Anyhow I an getting the IRND

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