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  1. #21

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    The Final Outcome

    Now, after a few months, I have a final outcome. I bought a B+W netural density filter and put it below the enlarging lens (screw into the lens mount). That cut down on my light output sufficiently. My initial exposure times with the APO Rodenstock 80mm lens are about 25 seconds at f.8.5-f.11. There is always some subsequent burning or dodging. Enlargments are 9x9 inches (image size) printed on 11x14 paper. This is on Oriental VC fibre paper, cold tone. Souped in Dektol 1:2 with benzotriazole added. THen selenium toned. The prints are looking lovely.

  2. #22

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    Hi Gary !
    If the bulb is too bright, get a less powerfull one... This may sound like a joke, but it worked for me. I replaced a 100W halogen by a 75 W and it was fine... Pay attention to the bulb voltage and mechanical details... So speak to the LPL importer to choose the correct bulb.
    What controls do you have on the head ? Do you have Cyan, Magenta and Yellow and another knob ? If yes, it could be the neutral density you need .... It is often graduated in stops (30 units density means one stop).
    You may also have the oportunity to put a sheet of white transluscent plexiglass on top of the mixing box, this will eat some light....
    The last solution is to use Bergger, Foma or Forte papers, as they are really slow.
    A color enlarger's goal is to be really bright as color papers (Ilfochrome particulary) are quite slow. So it is often too bright for B&W.
    Hope this helps

  3. #23

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    George,
    I spoke with the JOBO rep (they import the Fujimoto enlarger), and he advised against reducing the lamp output. He said that the balance is set for a particular wattage bulb. By the way, there are no "magenta and cyan" etc. settings, per se, as this is the VCCE model.

    I think that the reason it is so bright is that it really is a 4 x 5 enlarger, and most folks will be printing with their lamphead raised up many more inches than mine. The bright bulb will keep their printing times reasonably low (even though it makes my 6x6 printing times too high.

    THanks for your thoughts.
    Gary

  4. #24

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    I don't dodge or burn. I don't like to go under 2 seconds.
    I was at 1.4 and 1.6 seconds at f16 a few days ago. Dan

  5. #25

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    Quote Originally Posted by Gary Grenell
    George,
    I think that the reason it is so bright is that it really is a 4 x 5 enlarger, and most folks will be printing with their lamphead raised up many more inches than mine. The bright bulb will keep their printing times reasonably low (even though it makes my 6x6 printing times too high.

    THanks for your thoughts.
    Gary
    I think you are on the right track. I print MF with a 100 mm and LF with a 150mm. I just checked it out - using a 6x7 negative and focusing for an 8x10 enlargement, my light source elevations with the 100mm and 150mm enlarging lenses was 57cm and 86cm.

    If you are bothered by adding another piece of glass to the image path in the form of your ND filter, you could go to a longer focal length enlarger lens. This will raise up your light source and will extend your exposure times significantly. If you know someone with a 100 mm lens, try it on your enlarger. 100 mm is a very viable lens for MF and you will gain distance between your easel and light source and lengthen your exposure times.

  6. #26

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    I am not mathematically minded. I think it is a good idea to put in place the larger lens (even though I've spent a bloody fortune on that APO Rodagon lens). Do you have any idea what the percent increase in exposure time would be going from an 80mm to 100mm enlarging lens (given the same image size on the easel), the same degree of enlargement from the negative?
    Gary

  7. #27
    L Gebhardt's Avatar
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    My gut feeling is you won't see any difference with a longer lens. You still are focusing the same amount of light coming through the negative into the same area. Think of it as taking a picture. You don't change exposure based on focal length. The only difference is that you are closer to a macro size, but not that close.

  8. #28

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    But if the longer lens necessitates putting the light source at a further distance from the easel, would that not necessitate a longer exposure time (which is what I'm after)?

  9. #29

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    Quote Originally Posted by Gary Grenell
    I am not mathematically minded. I think it is a good idea to put in place the larger lens (even though I've spent a bloody fortune on that APO Rodagon lens). Do you have any idea what the percent increase in exposure time would be going from an 80mm to 100mm enlarging lens (given the same image size on the easel), the same degree of enlargement from the negative?
    Gary
    Hi Gary

    Boy, I am really rusty here but I will throw it out there to let someone else confirm or correct it.

    I believe it will work out this way. Going from an 80mm to a 100mm focal length will give you a 25% increase in distance from the plane of the negative to the easel.

    The inverse square law says the your light intensity will decrease by 1/d^2 or one over the square of the change in distance. In that case, believe you will see 1/1.25^2 (1 divided by the square of the increase in distance) which equals 64. This represents a 36% fall-off of light.

    If my calculations are correct (that's a big if!) this will not solve your problem and would not justify the $ for a new enlarging lens.

  10. #30
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    The inverse square law doesn't work in this case because the light is focused. I will try it out tonight, but I would bet a piece of paper on it that it won't change.

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