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Thread: Not enough exposure time

  1. #1
    My Passion Is Learning
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    Unhappy Not enough exposure time

    Hello, all.
    I just got the final pieces for my darkroom today! So I've started about running tests, the first one is to find my SCT. I'm finding that I'm struggling to get gray tones. Here's my details:

    Beseler 45M enlarger w/75 watt lamp
    Schneider-Kreuznach 135mm lens
    Ilford multigrade FB classic glossy paper
    I put a 4x5 FB+F negative in the negative stage and the grade 2 filter

    My first attempt to print I did three second brackets at f8. So I had exposure times of 3-30 seconds. The entire strip was completely black.

    My second attempt I did the same but at f22 and I got two gray tones (so 3 seconds and 6 seconds) with the rest of the strip bring black.

    The enlarger head is sitting where it does for enlarging a 4x5 negative to 8x10.

    My question is why I'm having to cut down so much light to get usable exposure times? Feels like the lamp is too hot or the lens is too close. But 75w seems appropriate and the head being halfway up the height of the stand seems appropriate also. Can anyone think of what I'm missing?

    Any direction would be lovely, I can't figure out what I'm doing wrong.

  2. #2
    Jac@stafford.net's Avatar
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    Re: Not enough exposure time

    Try developing a paper with no enlarger exposure. Let us know the results.
    .

  3. #3

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    Re: Not enough exposure time

    As you (I guess) saw a non suspicious projected image... only 3 things can go wrong:


    > Developer

    > Paper

    > Safety light


    IMHO the enlarger exposurse you made (f/22, 3 seconds) should not built density with development, guessing enlargement size was something common.

    I'd do that:

    1) Take a not exposed strip of paper, develop it without exposing it. Develop 2min does it go black ??

    2) Repeat development of a new unexposed paper strip (2 min) in total darkness. If now result is white then it was safety/ambient light. It if not it is paper or developer.

    3) Mix new developer to the right concentration, better is it is from a new purchase, try again.

    4) Buy a new paper box.

  4. #4
    Pastafarian supremo Rick A's Avatar
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    Re: Not enough exposure time

    Rick Allen

    Argentum Aevum

    practicing Pastafarian

  5. #5
    My Passion Is Learning
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    Re: Not enough exposure time

    I tested to see if it was my safelight earlier. I let a piece of paper sit exposed to the safelight for a few minutes and developed it. Pearly white!

    That tells me it's not my safelight or paper. I made a print successfully but it was 15 seconds at f32.

    The blacks seems fine so I don't think it's fogging. Im using ilford multigrade developer diluted 1+9.

  6. #6

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    Re: Not enough exposure time

    Are you positive the lens is at f22, etc..? A couple of mine have levers on the back to open them up completely for focusing even when set for f16, f22, etc.. I've left them opened up a couple of times by accident.

    Other than that, your methods and settings seem fine to me.

  7. #7
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    Re: Not enough exposure time

    This lens has no such release for the aperture, but I did check just in case! Though it's very precievibly darker at f32 than it is at f4.5. My question I guess would be, how dark should it be? My only logical conclusion is that my lamp is too bright. But I inspected it and it says it's only 75 watts. With the lens stopped down to f32, I can still see it quite easily under the safelight. Here's a photo of the circle of light (through the grade 2 filter) with the lens opened to f4.5 but with the regular lights on. I use three 500 lumen LED bulbs in this hybrid bathroom/darkroom, so it's not dim by any means! However the light from the enlarger is still very clearly visible. Click image for larger version. 

Name:	IMG_8136.jpg 
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ID:	168626

  8. #8
    Huub
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    Re: Not enough exposure time

    These very short exposure times happen more often with condensor enlargers. Generally it is a combination the high output of light of the enlarger and thin negatives. Probably there is nothing wrong with your safe lights, lamp, lens or aperture.

    Solution is to put a grey filter somewhere in the path of the light. I use a high qualty 3-step one that screws into the filter thread of the lens. There are also grey filters you can put into the filter drawer of the enlarger. You have to do a search here or on APUG to find the place where you can purchase them.

  9. #9

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    Re: Not enough exposure time

    Quote Originally Posted by TroyG View Post
    This lens has no such release for the aperture, but I did check just in case! Though it's very precievibly darker at f32 than it is at f4.5. My question I guess would be, how dark should it be? My only logical conclusion is that my lamp is too bright. But I inspected it and it says it's only 75 watts. With the lens stopped down to f32, I can still see it quite easily under the safelight. Here's a photo of the circle of light (through the grade 2 filter) with the lens opened to f4.5 but with the regular lights on. I use three 500 lumen LED bulbs in this hybrid bathroom/darkroom, so it's not dim by any means! However the light from the enlarger is still very clearly visible. Click image for larger version. 

Name:	IMG_8136.jpg 
Views:	30 
Size:	47.1 KB 
ID:	168626

    75w from a LED bulb throws x5 to x7 more light than a 75w from an incandescent lamp. For this reason you where needing x7 less exposure time, I guess.

    Please post what brightness has the image projected by enlarger, you can obtain the level in different ways:

    > A lux meter, like the (Amazon) Leaton Digital Luxmeter, 0.1Lux capable, $16 (interesting to hace something like that in the darkroom)

    > Use a Lux Meter app for the smartphone, it uses a sensor that's near screen for screen autobrigth feature. It gives too high readings with directonal light, but still a reference.

    > Use DSLR/SLR photometer and say the f/, shutter speed and iso

  10. #10

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    75 Watt bulb

    Quote Originally Posted by TroyG View Post
    Hello, all.
    I just got the final pieces for my darkroom today! So I've started about running tests, the first one is to find my SCT. I'm finding that I'm struggling to get gray tones. Here's my details:

    Beseler 45M enlarger w/75 watt lamp
    {snip}

    My first attempt to print I did three second brackets at f8. So I had exposure times of 3-30 seconds. The entire strip was completely black.

    My second attempt I did the same but at f22 and I got two gray tones (so 3 seconds and 6 seconds) with the rest of the strip bring black.

    The enlarger head is sitting where it does for enlarging a 4x5 negative to 8x10.

    My question is why I'm having to cut down so much light to get usable exposure times? Feels like the lamp is too hot or the lens is too close. But 75w seems appropriate and the head being halfway up the height of the stand seems appropriate also. Can anyone think of what I'm missing?

    Any direction would be lovely, I can't figure out what I'm doing wrong.
    If memory serves me, a 75 watt light bulb may be too bright. (The last 4x5" Beseler enlargers I worked with were in newspaper darkrooms in the late '60s.)

    What does the Beseler manual say is the correct light bulb to use?
    Does the bulb you are using have a thick white coating or are you using a "standard" light bulb?

    Also, if the light bulb is too intense, the enlarger head will find it difficult to dissipate the excess heat.

    For black and white work, you can always use a dimmer to reduce the light intensity.
    Last edited by AtlantaTerry; 19-Aug-2017 at 02:14. Reason: Cleaning up my prose.

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