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  1. #11
    Andrew Moxom's Avatar
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    Measure the light through your filter to make sure it is a 10 stop filter. Some vary.
    Please check out my website www.amoxomphotography.com and APUG Portfolio .....

  2. #12
    Greg Davis's Avatar
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    But that would still give plain over or under exposure, not higher base fog in the image area.
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  3. #13
    Ken Nadvornick's Avatar
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    Quote Originally Posted by ic-racer View Post
    Do a long 'exposure' with the shutter closed and see what happens. That way you can tell the difference between fogging from 'flare' light that came through the lens vs light leaking in through the bellows or around the lensboard etc.
    Yes. That's the ticket. Close off the system, isolate the variable in question, and test it under identical conditions.



    Ken
    "They are the proof that something was there and no longer is. Like a stain. And the stillness of them is boggling. You can turn away but when you come back they’ll still be there looking at you."

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  4. #14

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    I'd suspect a bellows pinhole toward the front of the camera or light leak around the lensboard that is small enough that it doesn't have much effect at shorter exposure times. It would cause overall fogging of the negative at longer times, but not the part of the film rebate covered by the filmholder rails.

    I had a similar problem on a camera with bellows that appeared practically brand new. There were a couple of corners that had small holes. Fixed now

    Do the flashlight/lightbulb test of your bellows and lensboards to rule this out before looking elsewhere.

    Best,

    Doremus

  5. #15
    Greg Davis's Avatar
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    To follow up, I left a sheet exposed in the camera with the same set up and lighting as before, but did not open the shutter, letting any light leaks do their thing. I had zero fogging, which leads me back to the idea that it may be flare or glare off the filter itself. I will try extending the shade more or placing the filter inside the camera behind the lens next.
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    Did millions of people suddenly disappear? This may have an answer.

    "No one knows that day or hour, not even the angels in heaven, nor the Son, but only the Father." -Matthew 24:36

  6. #16
    Hatchetman's Avatar
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    Interesting. I had the gel filter between a screw on filter (green) and the front of the lens.

  7. #17

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    Quote Originally Posted by Greg Davis View Post
    To follow up, I left a sheet exposed in the camera with the same set up and lighting as before, but did not open the shutter, letting any light leaks do their thing. I had zero fogging, which leads me back to the idea that it may be flare or glare off the filter itself. I will try extending the shade more or placing the filter inside the camera behind the lens next.

    Other possible causes of fogging are:

    Flare from internal reflections from a too-large image circle. This can be especially troublesome when there is a lot of bright areas just outside of the framed image. When using a compendium, extend it till it impinges on the ground-glass image then back off a bit for maximum effect.

    Light hitting the glass surface of the lens/filter itself from an oblique angle just outside the field of view. A well-adjusted compendium should fix this too.

    Do you have a coated ND filter? If not, then flare from light striking the filter surface will be worse. Still, I don't think this is your problem

    Do do the flashlight test just to be doubly sure. Not every pinhole shows up every time when simply exposing film. Extend the bellows to the max and check from every conceivable angle.

    And, are you really sure you are not just overexposing? A featureless shadow area overexposed will be a featureless denser area... In such cases, the negative will usually print well unless you have pushed the highlights way up onto the shoulder of the film curve. Check the near-shadow (e.g., Zone II and III) areas. If they have the detail you saw in your scene, then you have likely just overexposed, especially if the film rebate is clear (Zone 0).

    Keep us posted.

    Doremus

  8. #18
    Greg Davis's Avatar
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    It is definitely not plain overexposure. I have been doing this long enough to know what that looks like, and I took a very short exposure before hand to compare it to. I also checked again for pinholes and didn't see a single one. The elevated fog is killing the contrast. I am not using a multicoated filter, it is a Kodak gel filter, so I will try blocking out more lateral light.
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  9. #19
    Shawn Dougherty's Avatar
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    The combination of bellows flare and non-coated filter could certainly do it I would think. Let us know how it goes, Greg.

  10. #20
    Greg Davis's Avatar
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    Would a bag bellows help minimze bellows flare? I haven't tried that yet.
    www.gregorytdavis.com

    Did millions of people suddenly disappear? This may have an answer.

    "No one knows that day or hour, not even the angels in heaven, nor the Son, but only the Father." -Matthew 24:36

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