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  1. #31

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    Quote Originally Posted by 2F/2F View Post
    ...Two of my classmates are a lady who just turned 60, and a lady who has not even graduated high school yet. I am older than two of my instructors! The word "student" does not have an age limit, and does not equate with young and immature as a rule...and being older in no way makes one more correct as a judge of how others need to change...not to mention soliciting the experience of those with more experience than myself, and, of course, reading data sheets...
    I apologize for having thought that, since you're a student, you are in the neighborhood of 20 years old. That was a poor assumption, and was the only reason I posted in this thread.

    My very error underscores the point I was trying to make. Older people like me, with long experience, cannot be relied on as sources of absolutely correct information. Also, the number of data sheet errors I've seen is large.

    Let's move on and return this thread to a discussion of IR opacity.

  2. #32
    Marco B's Avatar
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    Quote Originally Posted by Sal Santamaura View Post
    Let's move on and return this thread to a discussion of IR opacity.
    Yes, please do!

    Because the OP is not the only one interested in the answers... I have been thinking of shooting Efke 820 IR film too with my Tachihara. However, before starting to waist film, it would definitely be nice to know if this is a REAL issue, or if it might be caused by other issues, like a small leak in the bellows. It seems to me we still haven't got a good explanation...

    And is there someone who can actually explain why a black bellows made to block light up into the (far) red, can not block the near infrared? Far red / near infrared as the film is sensitized too, is not yet the "heat" infrared as sensed by heat seeking missiles or goggles, because that is even further up in the longwaves spectrum, well beyond what film can capture. So it is unlikely that the simple heating up of the bellows due to for example sunlight, would cause re-transmittance of higher wavelength IR that could cause the fogging, or am I wrong here???

    Quote Originally Posted by keithwms View Post
    I used to have some horseman bellows that were not IR-proof.
    Keith has been the only one up to now definitely confirming a possible issue with some belows, but again, no real explanation here...

    Is there someone who could give new insights as to why the bellows are potentially "near-infrared" transparent?

    Marco
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  3. #33
    L Gebhardt's Avatar
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    If you start doing more tests could you try the Shen-Hao bag bellows. I have the same camera and a box of Maco 820 that has been in the freezer for too long. Your post may have saved me from assuming it had gone bad. If the Shen-Hao bag bellows works i will start with that.

  4. #34
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    Quote Originally Posted by Marco B View Post
    Keith has been the only one up to now definitely confirming a possible issue with some belows, but again, no real explanation here...

    Is there someone who could give new insights as to why the bellows are potentially "near-infrared" transparent?

    Marco
    Some plastics are transparent in the IR, maybe also down into the near-IR. I don't have my horseman any more but I recall that the bellows were not leather, they were some sort of thin (almost papery) synthetic material.

    Of course, the sensitivity of IR films currently on the market is rather low[*].... thus forcing rather long exposures if you are shooting with an opaque filter like a #87. So any minor light leak will be much more of an issue than it would be if the exposure were short so that the ratio of light through the lens and light through the leak were better. One really should do a careful bulb-in-the-bellows examination in a dark room.

    Anyway, it is a good policy to drape the whole camera in a darkcloth while shooting.
    [*] N.b. perhaps because higher-sensitivity IR films like HIE really do not store well, so manufacturers are less inclined to make them, given their concerns about their ability to move the product off the shelves with appropriate haste.
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  5. #35
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    I guess we first need to know which dark cloths are ir proof. I'm sure the manufacturers haven't tested this. Mine is made of two T-shirts sewn together and likely not ir proof. As I said, I've covered the camera even indoors and that didn't help. That's why I'm still not 100% convinced it's the bellows at fault here. It could be a the connection at the front/rear standards, right? The connection seems fine and I've never had an issue with light leaks. No leaks are visible with a xenon flashlight inside and camera in the dark room. I don't have a problem waisting roll film on more tests but not the 4x5 HIE that I have limited supply of. My expsosures with an 89b and the efke ir820 are about 4 seconds @22. Only 1/15@22 with the HIE, and 1/8@22 with the Konica 750. I'm hoping Chamonix will do some tests and that Hugo will get back to me but I'm really not expecting them too get back to me any time soon. The factory bellows are very thin. I'll try the shen hao bag bellows this weekend.
    Last edited by wildbill; 05-04-2009 at 12:19 AM. Click to view previous post history.
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  6. #36
    Marco B's Avatar
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    Quote Originally Posted by wildbill View Post
    It could be a the connection at the front/rear standards, right? The connection seems fine and I've never had an issue with light leaks. No leaks are visible with a xenon flashlight inside and camera in the dark room.
    OK, good to hear you did the light leak test, because that makes it more likely than there might be a real issue with the bellows, like Keith also suggests. Still, any more insights on the specifics and confirmation of this issue are welcome I think.

    And do recheck that connection at the front / rear standard a second time. Sometimes you have to turn over the camera and watch it closely from every direction to see or find an issue. And waiting 10-15 minutes in complete darkness to have your eyes adapt to the minutest amount of light, might help too in finding issues.
    My website

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  7. #37
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    UPDATE: I did another indoor test today with some konica 750 and my 6x12 roll film back which gives 6 exposures. Here are the resulting exposure #'s
    #1 put on a lens with caps on (metal lensboard w/baffle), extended bellows to about 300mm, covered bellows with aluminum foil (the fit of the foil was loose on the bottom), pulled darkslide for 2 minutes. film was fogged a bit overall and quite a bit more on the bottom 1/3 of the exposure where bellows wasn't covered.
    #2 pulled foil off, pulled dark slide for 2 minutes. tons of fog density
    #3 put leather shen hao bag bellows on and pulled dark slide for 4 minutes. no fog whatsoever.
    #4 shen hao bag bellows in direct sunlight, pulled dark slide, rotated camera around for 2 minutes. no fog whatsoever.
    #5 w/bag bellows removed lens caps and exposed film w/o filter for 1/60@5.6 pointing outside. film is over exposed but no fog.
    #6 with bag bellows exposed film with Red 29 filter 1/60@5.6. neg looks like it should w/o fog.

    At this point I'm convinced that standard chamonix 45N bellows* aren't opaque enough to use with ir films of any sort.
    *my bellows. If yours are IR proof and you'd like to trade, let me know!
    vinny
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  8. #38
    L Gebhardt's Avatar
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    Thanks for doing this test and publishing it. I will certainly keep my Shen-Hao bag bellows for IR work.

    I bet the Shen-Hao regular bellows would fit the camera just fine as well. I haven't tested this for IR work, but I think I remember hearing it works. It might be easy to get one if you need more extension than the bag allows.

  9. #39
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    Quote Originally Posted by wildbill View Post
    At this point I'm convinced that standard chamonix 45N bellows* aren't opaque enough to use with ir films of any sort.
    *my bellows. If yours are IR proof and you'd like to trade, let me know!
    vinny
    Thanks for doing this final conclusive test. I think you've now definitely proved there is an issue with the IR "opaqueness" of the standard plastic bellows, as Keith also pointed out. This is a big warning to other LF users like myself.
    Last edited by Marco B; 05-06-2009 at 01:57 AM. Click to view previous post history.
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    "Analog is chemistry + physics, digital is physics + math, which ones did you like most?"

  10. #40

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    My Shen Hao (HZX4x5-IIA model I think) is IR tight. I've tested both normal and bag bellows with Efke IR820. I've also photographed it with a digital camera using a R72 filter and a halogen light as an IR-source to see any leaks (which I did not notice).

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