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  1. #11
    DWThomas's Avatar
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    I ran a 120 roll of the IR820 in some tests last year and found with a 720 nm filter I needed about 6 to 8 stops over the ISO 100 reading; with a 760 filter, another stop was needed. I used HC110 dilution E (1+47), about 9 minutes at 20ºC and they were not thin negatives, although there were some features, such as a stream in shade that were like a black hole for IR.

    Be advised, someone else a while back got almost nonexistent results with an IR film that seemed to point to his off-brand IR filter being mismarked. It was probably one with a cutoff up in the 800s. I must say though that the cost of the big name filters is enough I might pass on the whole idea!

  2. #12

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    Quote Originally Posted by DWThomas View Post
    I must say though that the cost of the big name filters is enough I might pass on the whole idea!
    The Hoyas aren't that bad unless you need a really big size. (What I wish I could find economically, though, is a 720 nm *gel* that could be used over a flash.)

    One thing to remember about exposure with IR films is that the EI is *not* just a function of the film and the filter---it varies with the time of day, because the ratio of IR (which the film sees) to visible (which you and the meter see) varies. You might get EI 6 in the evening (when the light skews red) and EI 1.5 at midday, or something like that.

    -NT
    Nathan Tenny
    San Diego, CA, USA

    The lady of the house has to be a pretty swell sort of person to put up with the annoyance of a photographer.
    -The Little Technical Library, _Developing, Printing, And Enlarging_

  3. #13
    BetterSense's Avatar
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    For the ultimate in cheap filtration, I've got good results with this film using Lee lighting gels.

    http://chazmiller.com/projects/leeir.html
    f/22 and be there.

  4. #14

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    Quote Originally Posted by BetterSense View Post
    For the ultimate in cheap filtration, I've got good results with this film using Lee lighting gels.

    http://chazmiller.com/projects/leeir.html
    Oh, that's interesting. I've experimented with a similar stack of primary-colour filters over a flash (there was a nice thread on IR flash a few months ago), but got results that suggested I was seeing *much* less IR from the flash than other people had seen with 89B gels.

    Now, seeing that page, I wonder if maybe the difference was in the flash rather than the filter. More experimentation called for, obviously.

    -NT
    Nathan Tenny
    San Diego, CA, USA

    The lady of the house has to be a pretty swell sort of person to put up with the annoyance of a photographer.
    -The Little Technical Library, _Developing, Printing, And Enlarging_

  5. #15
    Nicholas Lindan's Avatar
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    Quote Originally Posted by ntenny View Post
    What I wish I could find economically, though, is a 720 nm *gel* that could be used over a flash.
    Those used to be really common. Wonder what happened.

    This might be of interest:

    http://amasci.com/amateur/irgoggl.html

    Now that I remember it, black unexposed/developed Ektachrome film can be used as an IR filter.
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  6. #16
    DWThomas's Avatar
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    Quote Originally Posted by ntenny View Post
    The Hoyas aren't that bad unless you need a really big size. (What I wish I could find economically, though, is a 720 nm *gel* that could be used over a flash.)

    One thing to remember about exposure with IR films is that the EI is *not* just a function of the film and the filter---it varies with the time of day, because the ratio of IR (which the film sees) to visible (which you and the meter see) varies. You might get EI 6 in the evening (when the light skews red) and EI 1.5 at midday, or something like that.

    -NT
    I ended up with a "Bower" IR72 that seems to be OK. I was after 77 mm so it could be adapted to any lens I might want to use and that extra glass tends to hurt price a lot (as I recall, it was around $50, but others were 3 times that). I got a 67 mm 760 filter in some even more unknown brand for a lot less money. It too appears to work OK, but 760 nm cutoff is really pushing it on the Rollei IR400 I used on my first pass -- as in, add 12 or 13 stops -- you're really down on the cutoff curve. The 760 is much more usable with the EFKE material.

    And yes, the effects of time of day, season of year, etc. seem to suggest no matter how carefully one meters, bracketing is a Good Thing(tm).

  7. #17
    Zvonimir Ervacic's Avatar
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    Quote Originally Posted by herb View Post
    I am thinking xtol does not like Efke. How about Rodinal??
    Any experience with Efke??
    Last summer I experimented with IR820 120 roll and Heliopan 715 filter. I use the filter on my light meter to read the exposure (reflected light metering). I set the light meter to ASA80 as I usually like to overexpose all films for a better shadows details. I developed the test roll in Xtol 1+2 for 16 minutes, 30 seconds agitation at beginning and 3 slow inversion at each minutes. The highlights are very dense, too dense for printing while the shadows are OK.

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