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  1. #61
    BetterSense's Avatar
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    It's MGIV RC

    It's a very very small bathroom with 5 incandescent lights over the mirror. I wish I had thought to unscrew about half of them before I tested. I just shot another negative at around 20 seconds and it looks like it turned out ok even though I didn't have the camera braced very well. My scanner really is rubbish and it looks better in person. This after inverting. I think I really should do something about my paper flatness issue.


    Last edited by BetterSense; 01-14-2009 at 10:50 AM. Click to view previous post history.

  2. #62
    BetterSense's Avatar
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    Well the last photo I took had pretty decent exposure at 15 seconds. After exposure, I metered the scene with my Program Plus on Auto. It selected 1/60s at f/16, with 200 film.

    I have a pretty good knowledge that my camera is f/300 because I measured the pinhole with my enlarger. Difference between f/16 and f/300 is four stops slower lens=less light.

    Now the difference between 1/60 and 15 is about 10 stops slower=more light. The difference is 6 stops.

    6 stops slower than 200 is ISO 3. Who knows how accurate this is due to reciprocity, but it's something to start with.

  3. #63
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    I haven't observed appreciable reciprocity failure with paper negatives in exposures many minutes long.

    A convenient method of metering for pinhole, if you have a handheld meter, is to set your meter to your working EI (exposure index); I rate my grade 2 paper at EI=3. Then meter the scene, and refer to the f/stop of your pinhole divided by 10. That is, if it's an F300 pinhole, then look for the recommended exposure time opposite F30 on the meter scale (you do this because most light meters don't read above about F128). Then simply multiply this recommended time by 10, to yield your actual exposure time.

    As a hypothetical example for an f/300 camera, I set my meter's EI to 3, meter the scene, then refer to the recommended time opposite f/30, which may read, say, 5 seconds. Simply multiply this time by 10, resulting in a recommended exposure time of 50 seconds.

    Since this exposure time is well in the range of the times one may encounter in projection enlargement in the darkroom using photo paper, don't worry about reciprocity failure.

    If your negative comes out appreciable underexposed using this method, it means that your working Exposure Index is too high, or you aren't developing long enough, or both. You can therefore use this method to dial in your working EI for your paper and processing methods.

    I've found that I typically develop my paper negatives for 3-4 minutes, rather than the 1-2 minutes I may use for developing prints, but do so using a more dilute solution, so I can pull it at the right time.

    ~Joe

    PS: Regarding your posted image, is the fogging coming from the camera, the makeshift darkroom, or both?

  4. #64
    BetterSense's Avatar
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    I have no idea at this point. It could be either.

  5. #65
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    Yeah, it looks like some fog; take care that with these long exposures, you need to fuss over all light leaks. You could do a normal exposure with your "lens" covered to see if you have leaks and where they are.
    "Only dead fish follow the stream"

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  6. #66
    Joe VanCleave's Avatar
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    Of course you want to test your camera for leaks, but I'd recommend starting with your darkroom setup. You want to know right up front if your box of paper has been fogged in the darkroom when it's been opened; not knowing this will throw off all subsequent tests.

    If you have a changing bag, try removing one sheet of paper from the box in the bag, then remove that paper in the dark room. Then do the fog test for darkroom leaks. There's two ways to do this; the easy way is to simply keep one part of the paper covered by an opaque object (a coin, etc.) and leave the paper exposed in the darkroom under "safe" lights for at least 5 minutes. Then process the paper normally. The other way is to faintly flash the paper with white light (like from an enlarger for a few seconds at the smallest aperture setting), then do the same test with a coin over the paper; this second method is more sensitive for subtle leaks or fogging from safelights.

    With either test, if you notice a density difference on the paper between the covered and uncovered parts of the paper, then you have a fogging issue.

    There's also the possibility that the paper in the box is already fogged. The only easy way I know to test for this is to put the box of paper, scissors and a daytank in the changing bag; remove one sheet, cut off a strip and place it into the daytank; seal the box of paper and daytank before removing your arms. Then process the paper in the daytank. You can then compare the density of the paper strip and try comparing its tone against the backside of the paper strip, which should be pretty close to the same shade of white.

    Once you know that your darkroom and safelights are good, then you can proceed with testing your camera for leaks. I've found with pinhole cameras you can often see the leak by illuminating one side with a bright articulating desk lamp in an otherwise dark room, and put your face up close to the insides of the camera, checking the corners and edges and seams for light. Of course, you can't check the camera's door or lid this way, unless the camera is big enough to fit inside(!), so you'll have to do a leak test by loading a sheet of paper into the camera (in your now safely-proven darkroom) and leave the camera, shutter closed, out in the bright daylight direct sun for an hour, changing the orientation occasionally. You should see fogging on the paper after processing.

    ~Joe

  7. #67
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    I think it was my camera. I looked in the loading slot and ran a high-powered flashlight around. Not only did the flashlight penetrate the foamcore even through both sides painted black, there were several seams with more pronounced leaks. I covered the entire thing in aluminum foil, and now the flashlight doesn't shine through even a little bit. Although my camera now looks like Sputnik.

  8. #68
    keithwms's Avatar
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    Good job. You can also apply that sticky felt stuff from a craft store to the innards of your camera.
    "Only dead fish follow the stream"

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  9. #69
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    Yay I think the aluminum foil was the ticket, and I had a fogging problem all along. I'm starting to notice bizarre contrast issues with the paper though. The bridge, being red, is underexposed, while the blue sky and rocks are completely blown out. I'm sure this scene would have turned out more normal with film, but then, maybe it wouldn't be as cool either.


  10. #70
    keithwms's Avatar
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    Yep welcome to The Contrast Issue. Now you can go back through some of the discussions and see if any of that works for you. I'd say, try preflashing first and foremost, and expect it to increase the sensitivity of your paper by a stop or so.

    The other thing, which is blazingly obvious but seldom stated, is that you can meter the contrast of your scene and know straight away whether a paper neg is going to work under "normal" exposure. In a low contrast scene you can get wonderful results. In a an 8 stop scene, well... and of course you can filter blue if that might tighten up the contrast in your scene.
    "Only dead fish follow the stream"

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